Chapter 09 Local Surface Water Management PlanCity of Chanhassen 2040 Comprehensive Plan313
Chapter 9Local SurfaceWaterManagement Plan
City of Chanhassen 2040 Comprehensive Plan314
City of Chanhassen, Minnesota
Local Stormwater Management Plan
Adopted December 12, 2018
COUNCIL:
Mayor Denny Laufenburger
Bethany Tjornhom
Jerry McDonald
Elise Ryan
Dan Campion
STAFF:
Vanessa Strong
Paul Oehme
Photos: City of Chanhassen
Wenck Associates, Inc.
WENCK ASSOCIATES, INC.:
Diane Spector
Erik Megow
Todd Shoemaker, P.E.
File 1481-0013
Prepared by:
WENCK Associates, Inc.
1800 Pioneer Creek Center
Maple Plain, MN 55359
Phone: 763-479-4200
Fax: 763-479-4242
City of Chanhassen 2040 Comprehensive Plan315
[This page intentionally blank for printing]
City of Chanhassen 2040 Comprehensive Plan316
Table of Contents
Page | i
1.0 INTRODUCTION AND PURPOSE ............................................................................................. 1-1
1.1 Purpose of Plan ................................................................................................... 1-1
1.2 Relationship to Other City Plans ......................................................................... 1-1
1.2.1 Comprehensive Plan............................................................................ 1-1
1.2.2 Storm Water Pollution Prevention Program ....................................... 1-1
1.2.3 Wellhead Protection Plan ................................................................... 1-2
1.2.4 Bluff Creek Natural Resources Management Plan .............................. 1-2
1.3 Relationship to Other Plans ................................................................................ 1-3
1.3.1 Metropolitan Council Water Resources Policy Plan............................ 1-3
1.3.2 Minnesota River Basin Plan ................................................................. 1-3
1.4 Relationship to Other Regulatory Agencies ........................................................ 1-3
2.0 REGULATORY FRAMEWORK .................................................................................................. 2-1
2.1 Chanhassen Ordinances and Policies .................................................................. 2-1
2.2 State Agency Regulatory Framework ................................................................. 2-1
2.2.1 Metropolitan Council .......................................................................... 2-2
2.2.2 Minnesota Pollution Control Agency .................................................. 2-2
2.2.3 Minnesota Department of Natural Resources .................................... 2-2
2.2.4 Minnesota Department of Health ....................................................... 2-3
2.2.5 Carver County and Carver SWCD ........................................................ 2-3
2.2.6 Watershed Districts and WMOs .......................................................... 2-4
2.3 Wetland Conservation Act .................................................................................. 2-8
2.4 Relationship to NPDES Stormwater Permit ........................................................ 2-8
2.5 Water Resource Related Agreements ................................................................ 2-8
3.0 ASSESSMENT OF PROBLEMS ................................................................................................. 3-1
3.1 Hydrologic Modeling ........................................................................................... 3-1
3.1.1 Areas of Known Flooding .................................................................... 3-1
3.2 Impaired Waters ................................................................................................. 3-1
3.3 TMDLs and UAAs ................................................................................................. 3-2
3.3.1 Total Maximum Daily Load (TMDL) Studies ........................................ 3-2
3.3.2 UAAs .................................................................................................... 3-3
3.4 Problems and Issues ........................................................................................... 3-4
4.0 GOALS AND POLICIES ............................................................................................................ 4-1
4.1 Goals and Policies ............................................................................................... 4-1
5.0 IMPLEMENTATION PLAN ....................................................................................................... 5-1
5.1 Permitting and Enforcement .............................................................................. 5-1
5.1.1 Current Ordinances and Potential Revisions ...................................... 5-1
5.1.2 NPDES Permit Implementation Requirements ................................... 5-7
5.2 Implementation Programs and Projects ............................................................. 5-7
5.2.1 Education and Outreach Program ....................................................... 5-7
5.2.2 Monitoring Program ............................................................................ 5-8
5.2.3 Operations and Maintenance ............................................................. 5-9
5.2.4 Capital Improvement Program .......................................................... 5-10
City of Chanhassen 2040 Comprehensive Plan317
Table of Contents
Page | ii
5.3 Implementation Plan Funding .......................................................................... 5-11
5.4 Addressing Identified Problems and Issues ...................................................... 5-15
6.0 AMENDMENTS TO THE PLAN ................................................................................................ 6-1
6.1.1 WMO Plan Amendments..................................................................... 6-1
6.1.2 Major Plan Amendments .................................................................... 6-1
6.1.3 Routine Updates .................................................................................. 6-1
7.0 REFERENCES ......................................................................................................................... 7-1
TABLES
Table 2.1. MCWD LGU Coordination Plan……………………………………………………………………………………………..2-4
Table 3.1. Impaired Waters in Chanhassen. .............................................................................................. 3-1
Table 3.2. Problems, issues, and opportunities. ........................................................................................ 3-4
Table 4.1. Water resources management goals. ....................................................................................... 4-1
Table 4.2. Comparison of TP-40 to Atlas 14 event depths......................................................................... 4-2
Table 4.3. Agencies with regulatory authority. .......................................................................................... 4-7
Table 5.1. Regulatory requirements of various agencies compared to Chanhassen current ordinances. 5-3
Table 5.2. Chanhassen LWMP Implementation Plan 2018-2027............................................................. 5-12
Table 5.3. Chanhassen LWMP Implementation Plan 2018-2027 by year. ............................................... 5-14
Table 5.4. Implementation actions addressing identified problems and issues...................................... 5-15
FIGURES
Figure 1.1. City of Chanhassen in located in the Twin Cities Metro Area, Minnesota. ............................... vii
Figure 2.1. Watershed Management Organizations in Chanhassen. ........................................................ 2-7
APPENDICES
Appendix A: Land and Water Resources Inventory
Appendix B:Hydrologic Modeling Update
City of Chanhassen 2040 Comprehensive Plan318
Acronyms
Page | iii
AIS Aquatic Invasive Species
BMP Best Management Practice
BWSR Board of Water and Soil Resources
cfs cubic feet per second
cfu colony-forming unit
Chl-a Chlorophyll-a
CIP Capital Improvement Program
DNR Department of Natural Resources
DO Dissolved Oxygen
EPA or USEPA US Environmental Protection Agency
F-IBI Index of Biotic Integrity for Fish
LA Load Allocation
LWMP Local Water Management Plan
Met Council Metropolitan Council
mg/L milligrams per liter
M-IBI Index of Biotic Integrity for Macroinvertebrates
MPCA Minnesota Pollution Control Agency
MS4 Municipal Separate Storm Sewer Systems
NPDES National Pollutant Discharge Elimination System
NWI National Wetland Inventory
SD Secchi depth
SWCD Soil and Water Conservation District
SWPPP Storm Water Pollution Prevention Program
TMDL Total Maximum Daily Load
TP Total phosphorus
TSS Total suspended solids
µg/L microgram per liter
WLA Wasteload Allocation
WD Watershed District
WMO Watershed Management Organization
City of Chanhassen 2040 Comprehensive Plan319
Executive Summary
Page | iv
The City of Chanhassen, Minnesota is located in northeastern Carver County (see Figure 1.1), except for
one small area in Hennepin County. It is bordered on the east by the City of Eden Prairie; on the north by
Shorewood; and on the west by Victoria and Chaska. Its southern border is the Minnesota River. The
City has land in four watersheds: the Carver WMO, Riley-Purgatory-Bluff Creek, Minnehaha Creek, and
the Lower Minnesota River Watershed Districts.
This Local Water Management Plan (LWMP) was prepared in conformance with Minnesota Statutes
103B.235 and Minnesota Rules 8410. This plan is intended to provide the City of Chanhassen with
information and direction in the administration and implementation of water resource management
activities within the City during the period 2018-2027. It serves as a guide to projects, provides for
effective allocation of resources, and sets forth a funding plan for projects and programs over the next 5
to 10 years.
A number of water resources-related problems, issues and requirements were identified in this planning
process. These include:
•The reissue of the State of Minnesota’s NPDES General Stormwater Permit in 2013 requires local
governments such as Chanhassen to adopt and enforce standards and ordinances for
development and redevelopment which limits stormwater runoff from sites over one acre in
size.
•New or expanded maintenance and administrative responsibilities are required in the NPDES
permit to control runoff and protect and improve water quality from City owned or maintained
land.
•All 4 WMO’s are updating their 10 year Comprehensive Plans. The City is required to amend
their LWMP to be consistent with each WMO
•In order to maintain and/or obtain primary responsibility for managing local water resources
additional ordinance revisions are required. The alternative is to defer the authority to the local
WMO
•Some of the lakes and streams in the City do not meet the state’s water quality standards for
recreation and aquatic life.
•Stream gullies and escarpments are contributing excess sediment into Bluff Creek and the
Minnesota River.
The LWMP updates the City’s goals and related policies to address the problems and issues that were
evaluated for the updated LWMP. The goals are as follows:
City of Chanhassen 2040 Comprehensive Plan320
Executive Summary
Page | v
Implementation
This LWMP includes an Implementation Plan to help achieve those goals through capital projects,
management programs, and operations and maintenance activities.
Capital Projects. The Riley-Purgatory-Bluff Creek WD has completed Use Attainability Assessments
(UAAs) and/or Total Maximum Daily Load (TMDL) studies for some of the waterbodies in the City. These
studies have identified potential actions that could help protect or improve water quality. The City
evaluates partnership opportunities with the Districts to undertake priority projects as project plans
develop. In addition, the City has been systematically surveying the condition of storm drainage system
features. These condition assessments have identified a number of potential improvement projects, and
priority actions are included in the Implementation Plan. The Implementation Plan also includes projects
to install water quality Best Management Practices (BMPs) with street or other construction projects.
Management Programs. The City operates several programs that directly or indirectly affect water
resources, including a Public Education and Outreach program. A variety of social and traditional media
are also used to inform and educate citizens. City and partnership events, workshops and festivals
provide additional opportunities for education.
The City of Chanhassen collaborates with the Metropolitan Council to participate in its Citizen Assisted
Monitoring Program (CAMP). Volunteer residents take samples from the following lakes: Lake Lucy, Lake
Minnewashta, Lake Riley, Lake St. Joe, Lake Susan, and Lotus Lake. Aquatic Invasive Species
management is implemented through a partnership with Carver County WMO, Riley Purgatory Bluff
Creek Watershed District, and local Lake Associations.
Operations and Maintenance Activities. The City undertakes a variety of operations and maintenance
actions, including actions required by its NPDES MS4 Permit. These include ongoing water body
inventory and condition assessments, erosion control monitoring, street sweeping, stormwater system
inspection, maintenance and repairs, road salt management, and a general education and outreach
program.
Goal 1.Promote abstraction through infiltration, reuse and other methods where practicable to
do so to provide flood protection, ground water recharge and improved water quality.
Goal 2. Achieve water quality standards in lakes, streams, and wetlands consistent with their
designated uses and established classifications.
Goal 3. Protect and rehabilitate wetlands to maintain or improve their function and value.
Goal 4. Prevent contamination of the aquifers and promote groundwater recharge to maintain
base flows in streams and wetlands.
Goal 5. Maintain primary responsibility for managing water resources at the local level and
continue coordination and cooperation with other agencies and organizations.
Goal 6. Cultivate an environmentally literate public to promote an active community role in
sustainable management of water resources.
City of Chanhassen 2040 Comprehensive Plan321
Executive Summary
Page | vi
Plan Updates
Section 6 of this Plan sets forth a process to update the LWMP in response to city operations, budget
planning, work requirements or WMO plan revisions. The Implementation Plan and Capital
Improvement Program (CIP) will be reviewed and updated periodically by the City as needed based on
new information or as new opportunities and requirements arise. At a minimum, the CIP will be updated
biannually. Major issues that result in potential significant revisions to the LWMP will be forwarded to
the Watershed Districts and WMO for discussion and review to determine if the LWMP will require a
formal update.
City of Chanhassen 2040 Comprehensive Plan322
Page | vii
Figure 1.1. City of Chanhassen in located in the Twin Cities Metro Area, Minnesota.
City of Chanhassen 2040 Comprehensive Plan323
Page | 1-1
1.0 Introduction and Purpose
1.1 PURPOSE OF PLAN
The City of Chanhassen is located in Carver County within the Twin Cities Metropolitan Area (Figure 1.1).
This Local Water Management Plan (LWMP) describes how the City of Chanhassen will fulfill the
requirements of Minnesota Statutes 103B.235 and Minnesota Rules 8410 in the management of the
water resources within the city during the period 2018-2027. It is a summary of the city’s management
goals and policies, and strategies, including a capital improvement program and review of local policies
and ordinances.
Minnesota Statutes 103B.231 establishes the purposes of water management planning in the Twin Cities
Metropolitan Area as to:
1.Protect, preserve, and use natural surface and groundwater storage and retention systems
2.Minimize public capital expenditures needed to correct flooding and water quality problems
3.Identify and plan for means to effectively protect and improve surface and groundwater quality
4.Establish more uniform local policies and official controls for surface and groundwater
management
5.Prevent erosion of soil into surface water systems
6.Promote groundwater recharge
7.Protect and enhance fish and wildlife habitat and water recreational facilities
8.Secure the other benefits associated with the proper management of surface and ground water
Minnesota statutes and administrative rules also require that city management of its water resources
be consistent with the requirements of the four watershed districts having land within its borders:
Riley-Purgatory-Bluff Creek Watershed District; Minnehaha Creek Watershed District; Carver County
WMO; and the Lower Minnesota River Watershed Management District.
1.2 RELATIONSHIP TO OTHER CITY PLANS
This LWMP is intended to address surface water management; ground water supply and wellhead
protection planning are separate from this Plan except as surface water management influences
groundwater.
1.2.1 Comprehensive Plan
The Comprehensive Plan is a blueprint for how the city manages its land use. The Metropolitan Council
in accordance with the Metropolitan Land Planning Act develops and updates regional planning policies
and requires that all cities periodically update their Comprehensive Plans to be consistent with those
policy plans. Thrive MSP 2040 and the 2040 Water Resources Policy Plan identify certain required
elements of local water resources planning. This Local Water Management Plan Update meets those
requirements.
1.2.2 Storm Water Pollution Prevention Program
Chanhassen is regulated by the State of Minnesota’s National Pollutant Discharge Elimination System
(NPDES) General Stormwater Permit as a Municipal Separate Storm Sewer System (MS4). In accordance
City of Chanhassen 2040 Comprehensive Plan324
Page | 1-2
with that permit, the city developed a Storm Water Pollution Prevention Program (SWPPP) comprised of
a series of Best Management Practices (BMPs) in six Minimum Control Measure (MCM) areas to prevent pollution and to manage and treat runoff discharged from the city into state waters. An annual report documents the specific actions taken in the previous year, which is presented to the public for review, approved by the City Council, and submitted to the Minnesota Pollution Control Agency (MPCA) for approval.
In 2006, the city was one of 30 cities statewide selected by the MPCA to undertake a special
Nondegradation Assessment as part of its NPDES permit. The purpose of the study was to assess
changes in stormwater runoff volume, total suspended solids (TSS) and total phosphorus (TP) loading
since 1988, and to predict how land change expected to 2020 would impact those parameters. The study
found that while runoff volumes had increased, pollutant loading had decreased as a result of city and
watershed district water quality treatment requirements.
A new General Permit became effective August 1, 2013, and the city and other MS4s were required to
prepare a new SWPPP and submit obtain renewal of coverage under the permit. Many of those BMPs
are incorporated into this LWMP.
1.2.3 Wellhead Protection Plan
Minnesota state statutes require the owners and operators of public drinking water systems to prevent
contamination of public water supply wells by effectively managing potential contaminant sources in the
area which contributes water to those wells. They must prepare a wellhead protection plan which
includes: a map showing the boundaries of the delineated wellhead protection area, a vulnerability
assessment of the well and the wellhead protection area, an inventory of potential sources of
contamination within the wellhead protection area, a plan to manage and monitor existing and
proposed potential sources of contamination, and a contingency strategy for an alternate water supply
should the water supply be disrupted by contamination or mechanical failure.
The city’s Wellhead Protection Plan (WHPP) addresses the ten municipal supply wells used by the city.
Initially completed in 2002, it was updated in 2011 to include new wells and additional analysis. The
WHPP includes an identification of a Wellhead Protection Area and an assessment of the vulnerability of
the wells to contamination. One well, an emergency backup well, was identified as vulnerable to surface
contamination, while the other wells were classified as not vulnerable. The uppermost source water
aquifer within the Drinking Water Supply Management Area (DWSMA) was identified as having mostly
low vulnerability to surface contamination.
Infiltration of stormwater is not desirable where the DWSMA indicates the aquifer is vulnerable to
contamination from the surface, and other stormwater BMPs are recommended. DWSMA vulnerability
is further described at the subwatershed level in Appendix A of this Plan.
1.2.4 Bluff Creek Natural Resources Management Plan
The Bluff Creek Natural Resources Management Plan was completed in 1996. The Management Plan
identified high-quality natural features for preservation as well as potential restoration projects. To
protect this area, several zoning and land use recommendations were intended to minimize new
impervious surface, control and limit stormwater runoff and pollutant loading, and protect or enhance
wildlife corridors and connectivity. Many of these recommendations were incorporated into the Bluff
Creek Overlay District zoning ordinance enacted in 1998. Maintaining and enforcing stormwater
City of Chanhassen 2040 Comprehensive Plan325
Page | 1-3
management requirements through this Plan and the Riley-Purgatory-Bluff Creek Watershed District are
integral to achieving the goals of the Bluff Creek Plan.
1.3 RELATIONSHIP TO OTHER PLANS
Several agencies manage programs or regulate activities for local stormwater or water resource
management. The following sections summarize those relevant to local water management planning.
1.3.1 Metropolitan Council Water Resources Policy Plan
The Metropolitan Council’s Water Resources Management Policy Plan is a framework to integrate water
resources management and protection with planning for the Metro region’s growth. In 1995, the
Metropolitan Land Planning Act was amended to require that each city and township's comprehensive
plan include a local water management plan. These local plans need to be consistent with Minnesota
Statutes 103B and Metropolitan Land Planning Act requirements. Local water management plans are
reviewed by the Met Council as part of the local comprehensive planning process prior to their approval
by the WMO and adoption by the city or township.
In addition to the local stormwater plan elements required in statute and administrative rule, the Policy
Plan expects communities to show that they are committed to the Met Council’s goal of no adverse
impact (nondegradation) for area water resources. Local plans should include actions such as ordinances
requiring runoff water quality treatment and limiting the rates and volumes of runoff; adopting Best
Management Practices for development and redevelopment; and wetland management planning. The
Policy Plan places a special emphasis on nondegradation of lakes identified as Priority Lakes. The Met
Council defines Priority Lakes as lakes of high regional recreational value that are at least 100 acres in
size; supply drinking water; have very good water quality; or have exceptional significance for wildlife
habitat. Lakes in Chanhassen that have been designated as Metro Priority Lakes are: Minnewashta, Ann,
Lotus, and Riley.
1.3.2 Minnesota River Basin Plan
The Minnesota River flows southeast from its source at Big Stone Lake on the South Dakota border to
Mankato then northeast to join the Mississippi River at Fort Snelling (about 335 total miles). It covers
approximately 16,770 square miles, roughly 10 million acres. Thirteen major watersheds in Minnesota
drain into the basin, which touches 37 counties. Most of Chanhassen is located in the Lower Minnesota
River subbasin. The 2001 Minnesota River Basin Plan (MPCA 2001) lays out a broad framework for
directing environmental programs toward improving water quality in the Minnesota River, its tributaries
and other water bodies. Priority actions include reducing nutrient, sediment, and bacteria inputs to the
river and improving the health of biologic communities.
1.4 RELATIONSHIP TO OTHER REGULATORY AGENCIES
The LWMP is intended to meet requirements outlined in Minnesota Rules 8410 and Minnesota Statutes
103B as well as provide a user-friendly tool for day-to-day management of the city’s water resources. The
LWMP provides the following information, as required in the Minn. Statutes 103B.235.
•Existing and proposed physical environment and land use within the city
•Drainage areas and the volumes, rates, and paths of stormwater runoff
•Identification of stormwater storage areas
City of Chanhassen 2040 Comprehensive Plan326
Page | 1-4
•Performance standards for water quality and water quantity protection
•Implementation program
•Capital improvement program
The Plan was also written with consideration of the needs, requirements and direction outlined in the
following:
•Local Water Management Rules – Minn. Rules 8410
•Wetland Conservation Act – Minn. Rules 8420
•Minnesota Pollution Control Agency Water Quality Standards – Minn. Rules 7050
•U.S. Army Corps of Engineers Section 404 Clean Water Act
•Metropolitan Council Water Resources Policy Plan May 2005
•Riley-Purgatory-Bluff Creek Watershed District Water Management Plan - January 2011
•Minnehaha Creek Watershed District Comprehensive Water Resources Management Plan – April
2007/ January 2018
•Carver County WMO Comprehensive Water Resources Management Plan – October 2010
•Carver County Groundwater Plan - 2016
•Lower Minnesota River Watershed District Water Management Plan - December 2011
•Metropolitan Surface Water Management Act (Chapter 601, Laws of 1990)
•Use Attainability Analyses (UAAs) for lakes and streams in the city
•The approved TMDLs for turbidity and fish biotic impairments in Bluff Creek
The watershed organizations and their respective jurisdictions within the city are shown on Figure 2.1.
The LWMP is intended to satisfy the rules set forth in the current watershed management plans. The
city will participate in upcoming revisions, evaluate any future watershed management plan
amendments in relation to the LWMP and incorporate items as needed.
City of Chanhassen 2040 Comprehensive Plan327
Page | 2-1
2.0 Regulatory Framework
2.1 CHANHASSEN ORDINANCES AND POLICIES
The city has enacted several ordinances to protect and manage its water resources.
Chapter 19 of Chanhassen City Code addresses design standards and requirements for water and sewers.
Article V addresses illicit discharge detection and elimination within Chanhassen storm sewer systems.
Article VII spells out development standards and design elements intended to implement the standards
and achieve the goals set forth in this plan in order to preserve, protect and improve the city’s surface
water resources. Specific elements within Article VII include erosion prevention and sediment control
requirements, hydrologic and hydraulic design elements, water quality, rate control and volume
reduction requirements. Those design standards include more stringent requirements for developments
that discharge into Assumption Creek. That Article also establishes a Surface Water Management Utility
and associated fees for operation of this utility.
Chapter 20 is the city’s Zoning Code. Article VI establishes wetland management classifications and
standards for managing and protecting wetlands in the city. The City of Chanhassen is the responsible
Local Government Unit (LGU) for the administration of the Wetland Conservation Act (WCA) in all areas
of the city. This article includes standards for setbacks and for establishing and maintaining buffer strips
adjacent to wetlands, and policies and procedures for altering wetlands and mitigating impacts to
wetland functions and values.
Article V establishes the city’s Floodplain Overlay District and floodplain management standards. The
ordinance establishes the regulatory flood protection elevation as no lower than two feet above the
elevation of the regional flood. The ordinance also establishes what land uses may occur within the
Overlay District under what conditions.
Article VII sets forth the city’s Shoreland Management District ordinances. The lakes and streams within
the city that are regulated under this ordinance are established by management classification. The
article includes minimum lot size and width requirements, structure and onsite sewage system setbacks,
and limitations on altering and clearing vegetation and adding impervious surface. Article XXVIII
establishes bluff protection standards in general.
Article XXXI establishes the Bluff Creek Overlay District and standards for protecting the quality and
extent of the natural features within the District, which is centered on Bluff Creek. The Overlay District
defines a Primary Zone, which is intended to be open space, and a Secondary Zone, in which regulated
development may occur. Within this Secondary Zone, the ordinance requires a more stringent bluff
setback; limits the amount of impervious surface allowed based on bluff slope; encourages terrain-
adaptive architecture and density clustering; and requires preservation of natural habitat or, within the
Secondary Zone, mitigation of any unavoidable impacts.
2.2 STATE AGENCY REGULATORY FRAMEWORK
Many agencies manage programs or regulate activities for local stormwater or water resource
management. The following sections summarize those of primary relevance to urban local water
management planning.
City of Chanhassen 2040 Comprehensive Plan328
Page | 2-2
2.2.1 Metropolitan Council
The Metropolitan Council’s Water Resources Management Policy Plan includes a range of programs
administered by various governmental and private agencies for management of water resources in the
Metro area. Several of Met Council’s programs of interest to cities include the following:
•Development of targeted watershed pollutant loads
•Review of watershed and local water plans and comprehensive plans for consistency with
metropolitan goals and objectives
•Watershed Outlet Monitoring Program (WOMP)
•Citizens’ Assisted Lake Monitoring Program (CAMP)
•Environmental Information Management System
•Regional Water Supply Plan for the Metropolitan Area
2.2.2 Minnesota Pollution Control Agency (MPCA)
The MPCA administers several programs applicable to local storm water management planning. The
MPCA monitors water quality, sets standards, and implements various controls. Following are two
programs related to water quality.
•The MPCA manages the National Pollutant Discharge Elimination System (NPDES) Phase II
permitting for small municipal separate storm sewer systems (MS4s) and construction and
industrial discharge permitting
•The MPCA implements the Clean Water Act, which requires that states adopt water quality
standards to protect waters of the state. The EPA and MPCA require preparation of Total
Maximum Daily Load (TMDL) studies to identify the source of pollutants and plans for bringing
the water resources into compliance. Lake Susan, Riley Lake, and Lotus Lake are impaired by
excess nutrients; Bluff Creek is impaired by excess turbidity and does not meet state fish biology
standards; and the Minnesota River does not meet turbidity standards. Several lakes and the
Minnesota River do not meet mercury or PCB standards and have been listed on the MPCA’s
303(d) list of impaired waters. Section 3.2 discusses impaired waters in more detail.
2.2.3 Minnesota Department of Natural Resources (DNR)
The DNR manages and protects the state’s natural resources and operates numerous programs. The
department provides technical assistance and information regarding best management practices,
natural resource management, incorporating natural resource conservation in land use planning, and
lakescaping.
The Fisheries Division monitors and improves fisheries within the state. It also promotes fishing
opportunities and provides grants to assist in the construction of fishing piers. The Ecological and Water
Resources (EWR) Division focuses on an overarching vision of “Healthy Watersheds throughout
Minnesota.” The EWR Division also provides the following services:
•Maintains an inventory of public waters and operates permit programs for working in public waters
or for appropriating public waters;
•Oversees the state’s floodplain management program;
•Provides local stewardship by coordinating the Mississippi River Critical Area and MNRAA programs
and the Shoreland Management program;
City of Chanhassen 2040 Comprehensive Plan329
Page | 2-3
•Collects, analyzes, and provides ecological information, including:
Location and management of rare resources (endangered and threatened species, critical
habitats, high quality natural communities);
Management of harmful exotic species, fish and wildlife diseases, and negative environmental
impacts of human development;
Management and restoration of important ecological processes in river systems and key natural
areas; and
Development of information about Minnesota's ecosystems and their significance to a
sustainable quality of life.
The DNR’s webpage at http://www.dnr.state.mn.us/lakefind/index.html is LakeFinder, a DNR supported
tool that combines information from various DNR Divisions, as well as other state agencies, such as
Minnesota Pollution Control Agency (water quality) and Minnesota Department of Health (fish
consumption). This tool contains data for more than 4,500 lakes and rivers throughout Minnesota.
The DNR also provides a variety of specialized programs oriented to property owners or neighborhood
groups, such as the Aquatic Plant Management, Urban Fisheries and Fishing in the Neighborhood,
Neighborhood Wilds, and Metro Greenways programs.
2.2.4 Minnesota Department of Health (MDH)
The Environmental Health Division of the MDH administers numerous programs of interest to local
water management planning, including the following.
•Drinking water protection
•Wellhead protection
•Lake and fish monitoring (in partnership with DNR/MPCA)
•Environmental Health Services
•Health risk assessment, site assessment, and consultation
•Well management
The city worked with the MDH to develop a Wellhead Protection Plan (WHPP).
2.2.5 Carver County and Carver SWCD
Carver County provides a variety of programs throughout the county that relate to water resources
management. County staff manage feedlot and septic system programs, and undertake lake and stream
monitoring for water quality where that is not undertaken by a Water Management Organization
(WMO). The county also provides Aquatic Invasive Species (AIS) monitoring and works to stop their
spread. Common carp, curlyleaf pondweed, Eurasian water milfoil, and zebra mussels have been found
in some of the lakes in Chanhassen. The county has in place an approved groundwater plan, and offers
financial assistance to property owners to properly seal unused or abandoned wells.
The Carver Soil and Water Conservation District (SWCD) provides outreach and assistance to both urban
and agricultural land owners to help them protect and improve lakes, streams, and wetlands in the
county. The SWCD promotes environmentally-friendly landscaping, offers financial assistance for
shoreline restorations and other Best Management Practices (BMPs), and sponsors student and adult
education programming.
City of Chanhassen 2040 Comprehensive Plan330
Page | 2-4
2.2.6 Watershed Districts and WMOs
Watershed Management Organizations (WMOs) in the metro area are required by statute to prepare
and administer water management plans that establish watershed-wide goals, policies, and regulations.
Local governments are also required by statute to prepare and administer local water management
plans that establish local goals, policies, and regulations regarding those water resources management
areas that are consistent with the watershed plans. Chanhassen has land within the boundaries of three
watershed districts and one county WMO (see Figure 2.1):
•Riley-Purgatory-Bluff Creek Watershed District
•Minnehaha Creek Watershed District
•Lower Minnesota River Watershed District
•Carver County WMO
Minnehaha Creek WD Local Plan Requirements. The MCWD updated its Watershed Management Plan in
2017. The City of Chanhassen has land in the Lake Virginia, Christmas Lake and Lake Minnetonka
subwatersheds. In addition to the general requirements for Local Management Plans set forth in
Minnesota Rules 8410, additional items must be addressed in the city’s Local Plan.
One focus of the MCWD plan is fostering collaboration between the District and the cities to achieve
mutual water and natural resource management goals. To that end the local plan should include:
•Locations of publicly-owned lands such as parkland, right of way, or public facilities that may
provide opportunities for collaborative stormwater management BMPs.
•Lands that may potentially develop or redevelop within the planning timeframe.
•Planned Infrastructure improvements or parks or open space acquisitions.
•Potential to use development and redevelopment regulation to create incentives to protect water
and other natural resources, including controls on removing mature trees.
•Ways in which the city’s development review process encourages low impact development, and
how the city ensures BMPs are adequately maintained post-construction.
•A description of how the city will proactively and at least annually communicate and coordinate
with the District on implementation efforts and opportunities for collaboration.
A second focus is the MCWD Local Governmental Unit (LGU) Coordination Plan. Through the
Minnehaha Creek Watershed District (MCWD) 2018 Water Management Plan, LGU coordination is
identified as an integral component of the Local Water Management Plan. A coordination plan is
requested to define a set of protocols that supports ongoing communication and promotes value-added
collaboration between the District and LGU. Through these communications, the District and LGU will
coordinate programs and resource deployment and be best suited to identify areas of collaboration and
partnership. The goal of the coordination plan is to create a framework to maintain awareness of needs
and opportunities to co-plan water and land use early in the planning process, while also identifying
LGU services and expectations of MCWD.
Through the Local Water Plan, the District invites a partnership framework that fosters increased early
coordination of land use and water resource management to achieve its water quality goals.
Table 2.1. MCWD LGU Coordination Plan.
Element When and How Department & Position Responsible
i. Annual meeting to review LWMP
implementation
September annual
meeting
Water Resources Department -
Water Resources Coordinator
City of Chanhassen 2040 Comprehensive Plan331
Page | 2-5
ii. Transmittal of annual NPDES
MS4 report
Available on
MPCA website
MPCA staff via MPCA website
iii. Notice of and consult with the
LGU on its land use,
infrastructure, park and
recreation and capital
improvement planning efforts
Annual meeting Planning Department - staff
iv. Notice to the District on small
area plans and other focused
development or redevelopment
actions
Agency Review
Request email
transmittals will
continue to be
sent as
applications and
development
proposals are
received
Planning Department - staff
v. Notice of alterations within the
LGU MS4 system for District
maintenance of its watershed-
wide hydrology and hydraulics
model.
September annual
meeting
Water Resources Department -
Water Resources Coordinator
vi.1.Notice of prospective
development/redevelopment
and receive proposed
preliminary plats and
development plans
Agency Review
Request email
transmittals will
continue to be
sent as
applications and
development
proposals are
received
Planning Department - staff
vi.2.Procedures by which the LGU
ensures permit applicants are
aware of permitting authority of
both bodies
Agency Review
Request email
transmittals will
continue to be
sent as
applications and
development
proposals are
received
Water Resources Department -
Water Resources Coordinator
vi.3.a.Pre application and permit
reviews
Agency Review
Request email
transmittals will
continue to be
sent as
applications and
development
proposals are
received
Planning Department - staff
City of Chanhassen 2040 Comprehensive Plan332
Page | 2-6
vi.3.b
.
Construction site inspection and
compliance
Annual email
transmittal and
meetings as
needed
Water Resources Department -
Natural Resources Technician
vi.3.c.Enforcement of water resource
rules of MCWD and LGU
Water Resource
Permit Application
email
Water Resources Department - staff
vi.3.d
.
Implementation of the Wetland
Conservation Act where LGU is
acting as WCA LGU
WCA Notice
emails
Water Resources Department - staff
vi.3.e
.
Implementation of District Rules
where LGU is authority
Water Resource
Permit Application
email
Water Resources Department - staff
Riley-Purgatory-Bluff Creek WD Requirements. The Riley-Purgatory-Bluff Creek Water Management Plan
requires Local Water Plans (LWP) to meet the standards set forth in Minnesota Rules 8410. In addition,
cities must submit an annual compliance report describing its annual achievements and progress
towards meeting its goals. The LWP should also describe the self-evaluation process the city will use to
assess whether those goals and actions should be revised.
Lower Minnesota River WD Requirements. The Lower Minnesota River Third Water Management Plan
requires Local Water Plans (LWP) to meet the standards set forth in Minnesota Rules 8410. The District
will spot-check projects and programs for continued compliance with the approved LWP.
Carver County WMO Requirements. The Carver County WMO Comprehensive Water Management Plan
requires Local Water Plans (LWP) to meet the standards set forth in Minnesota Rules 8410. In addition,
if the city desires to take on regulatory responsibility, the Plan should state so, and describe the local
controls, policies, and procedures it will use to administer the permitting program, and demonstrate it
has the technical capacity to do so.
City of Chanhassen 2040 Comprehensive Plan333
Page | 2-7
Figure 2.1. Watershed Management Organizations in Chanhassen.
Source: Minnesota Board of Water and Soil Districts.
City of Chanhassen 2040 Comprehensive Plan334
Page | 2-8
2.3 WETLAND CONSERVATION ACT
The adminitrative responsibilities for the Wetland Conservation Act of 1991 (WCA) will continue to
rest with the city. Wetland LGU responsibilities include:
•Review and approve wetland delineations and determinations
•Review and approve wetland exemption / no-loss applications
•Review and approve wetland replacement plan applications
•Coordinate Technical Evaluation Panel (TEP) meetings
•Send Notices of Application and Decision to the TEP
•Enforce wetland replacement monitoring requirements, review monitoring reports and certify
replacement wetlands
•Work with DNR and Carver County to enforce WCA violations
2.4 RELATIONSHIP TO NPDES STORMWATER PERMIT
The city holds a permit from the MPCA to discharge stormwater into waters of the state through
the MPCA’s NPDES General Stormwater Permit. The permit specifies that the city must develop,
receive MPCA approval of, and implement a Stormwater Pollution Prevention Plan (SWPPP) that
addresses a series of Best Management Practices (BMPs) for the following six minimum control
measures established by the EPA:
1.Public education and outreach
2.Public participation/involvement
3.Illicit discharge detection and elimination
4.Construction site runoff control
5.Post-construction runoff control
6.Pollution prevention/good housekeeping during municipal operations
The city’s previous SWPPP was approved in 2003 and amended in 2006. The State of Minnesota
adopted a new NPDES General Stormwater Permit effective August 1, 2013, and the city submitted a
permit reapplication in December 2013. Approval of the new permit and SWPPP was received in 2014.
Activities and policies to be included in the SWPPP are prescribed in the General Permit, and include
many of the actions and policies set forth in this LWMP.
2.5 WATER RESOURCE RELATED AGREEMENTS
Water resource-related agreements, including Joint Powers Agreements, are typically struck between
agencies or entities with overlapping regulatory interests or geographic similarities. The city has the
following agreements:
•Cooperative agreements with RPBCWD providing for property use, construction, maintenance
and credit-sharing for Susan Park Pond project and Chanhassen High School stormwater reuse
projects (2018); Cooperative agreement for the Lake Susan spent-lime water-quality
improvement project (2015); Pursuing a cooperative agreement with RPBCWD for efficient joint
administration of financial assurances secured for regulatory purposes (2018)
City of Chanhassen 2040 Comprehensive Plan335
Page | 2-9
•Memorandum of Agreement Between Carver County Land and Water Services and the City of
Chanhassen Regarding Water Quality Education (MS4 Requirements), AIS and Targeted
Monitoring Within City Boundaries.
•Agreement Between the Carver Soil and Water Conservation District and the City of Chanhassen
Relating to Urban Development Review and Site Inspection Services; Wetland Conservation Act;
Individual Homeowner Natural Resource Issues.
•1996 was the last executed cooperative agreement with MCWD. The city and MCWD are
working on an interim agreement for regulatory responsibility during the current Plan and
ordinance process
City of Chanhassen 2040 Comprehensive Plan336
Page | 3-1
3.0 Assessment of Problems
3.1 HYDROLOGIC MODELING
As part of this Plan, the HydroCAD hydrologic and hydraulic models for the city were updated to include
the most recent watershed and basin information. There are fifteen individual HydroCAD models for the
city. Issues raised by these models are discussed in Appendix A in the Subwatershed Summaries. The
purpose of performing this modeling is for planning level assessments. The models were not calibrated
to actual runoff and flows, and are not intended to be flood studies. The models were executed for the
100-year Atlas 14 precipitation event. Model output is quite lengthy and is available electronically. The
output files are incorporated into this Plan as Appendix B. In, addition in 2003, the Minnehaha Creek
Watershed District (MCWD) completed a multi-year Hydrologic, Hydraulic, and Pollutant Loading Study
(HHPLS) to document the physical and biological characteristics of the watershed which includes
projected runoff rates and volumes.
3.1.1 Areas of Known Flooding
On June 19, 2014, 4.98 inches of rain fell in less than 24 hours at the National Weather Service
monitoring site in Chanhassen, a nearly 25-year return interval event. Almost 4.5 inches of rain had
fallen in the weeks preceding this storm event, and the ground was saturated and ponds and wetlands
were still full. Localized flooding occurred at a number of locations. These included both ongoing
problem areas as well as locations where no or minimal flooding had been observed before:
•Market Boulevard north of MN T.H. 5
•Pipewood Curve
•Kerber Boulevard between Saddlebrook Curve and Sierra Trail
•Lake Riley Boulevard at Lyman Boulevard
•Old 212 near Moon Valley Gravel Pit
3.2 IMPAIRED WATERS
Waters that do not meet state water quality standards are listed as “Impaired” by the State of
Minnesota will require additional analysis in the form of a Total Maximum Daily Load (TMDL) study. A
TMDL is the maximum amount of a pollutant a waterbody can receive and still meet water quality
standards. The TMDL study identifies the sources and magnitude of pollutant loading and establishes a
numeric load reduction that must be made for each source.
Table 3.1. Impaired Waters in Chanhassen.
Lake/Stream DNR Lake #
/Reach # Affected Use Pollutant
Minnewashta 10-0009 Aquatic consumption Mercury FT1
Lucy 10-0007 Aquatic consumption Mercury FT1
Ann 10-0012 Aquatic consumption Mercury FT1
Susan 10-0013 Aquatic consumption/Aquatic
recreation Mercury FT1 and Excess Nutrients
Christmas 27-0137 Aquatic consumption Mercury FT1
Rice Marsh 10-0001 Aquatic recreation Excess Nutrients
City of Chanhassen 2040 Comprehensive Plan337
Page | 3-2
Lotus 10-0006 Aquatic consumption/Aquatic
recreation/Aquatic life
Mercury FT1 , Excess Nutrients, and
Fish Bioassessments
Riley 10-0002 Aquatic consumption/Aquatic
recreation/Aquatic life
Mercury FT1 , Excess Nutrients, and
Fish Bioassessments
Bluff Creek 07020012-710 Aquatic life Fish IBI2, Turbidity
Minnesota
River 07020012-506 Aquatic consumption/Aquatic life Mercury FT1, Mercury WC1, PCB
FT1, Turbidity
Assumption
Creek 07020012-582 Aquatic life Fish Bioassessments
1 "FT" means mercury or PCBs in fish tissue while “WC” means in the water column.
2 Index of Biotic Integrity. A measure of the quantity and quality of aquatic life.
Source: MPCA 2018 draft 303(d) list of impaired waters.
3.3 TMDLS AND UAAS
A TMDL was completed and approved in 2013 for the Bluff Creek biotic integrity and turbidity
impairments. A statewide TMDL has been completed for the mercury impairments. The Riley-Purgatory-
Bluff Creek Watershed District has completed Use Attainability Analyses (UAAs) for Lake Susan, Lake
Lucy, and Lake Ann. The UAAs are scientific assessments of a water body’s physical, chemical, and
biological condition. The studies include water quality assessments and recommendations for protective
and/or remedial measures for the studied lakes and their directly tributary watersheds. The results of
these UAAs provide the city guidelines for water resource improvement projects for these water
bodies. Although the UAAs provide some background data that may be used towards preparation of a
TMDL they do not meet MPCA criteria for a TMDL document.
3.3.1 Total Maximum Daily Load (TMDL) Studies
Bluff Creek Turbidity and Fish Biota TMDL. Bluff Creek is listed by the Minnesota Pollution Control
Agency (MPCA) as impaired for aquatic life use due to excess turbidity levels and low fish biota scores.
The Turbidity and Fish Biota TMDL was approved in 2013. The Bluff Creek TMDL Biological Stressor
Identification Report identified sediment, metals, habitat fragmentation, and flow as stressors to fish
biota. Although the TMDL Report discusses all of these stressors, Wasteload Allocations (WLAs) were
made only for total suspended solids (TSS), which represents a surrogate for both turbidity and fish
biota.
Chanhassen’s TSS Wasteload Allocation requires an 88 percent reduction in TSS contributed to the
stream. Primary sources of sediment are stream bank and bluff erosion, as well as poorly vegetated
ravines and gullies. An inventory and assessment of the Bluff Creek lower valley was completed to
identify sites contributing excessive amounts of sediment to Bluff Creek and to determine feasible
options for addressing sources of excess sediment delivery to the stream.
Five sites were classified as severe and are highest priority for stabilization and restoration, as was the
stream just below the Hennepin County Regional Trail Corridor culvert crossing. The stream channel has
downcut significantly below that culvert, and the culvert is being undermined, which could lead to
future failure. This large drop also disrupts the connectivity of the creek, fragmenting habitat. Fish and
other aquatic organisms are not able to migrate upstream of the culvert. Correction of the severe
erosion and addition of a fish passage to reconnect the creek above and below the culvert were
identified as priority implementation projects.
City of Chanhassen 2040 Comprehensive Plan338
Page | 3-3
South Metro Mississippi Total Suspended Solids TMDL. The South Metro Mississippi TSS TMDL was approved in 2016. This TMDL would require a 25 percent reduction in TSS load from MS4 communities
such as Chanhassen. MS4s can demonstrate they meet this reduction by implementing a suite of BMPs
that the MPCA will develop, or by showing that pollutant loads from their community meet or are less
than the target load of 154 lbs/acre/year. This proof can be accomplished through water quality
monitoring or modeling.
Twin Cities Metropolitan Chloride TMDL. This study includes TMDLs for 37 of the 39 lakes and streams in
the Metro Area that are impaired by excess chloride levels. The report also identifies high-risk
waterbodies where monitoring data indicates that resource is approaching the impairment threshold.
There are no chloride-impaired waters in Chanhassen, but the city is located within the tributary area of
Minnehaha Creek, which is impaired by excess chloride. In addition, Bluff Creek has been classified as a
high-risk waterbody. No specific load reductions were identified for Bluff Creek or any other waterbody
in Chanhassen, but the TMDL suggests that all cities where high-risk resources are located consider
developing a chloride management plan for those lakes and streams. In general, the TMDL suggests that
regardless of whether or not runoff drains to an impaired or high-risk waterbody road authorities and
other regulated entities take proactive steps to reduce the application of road salt for winter ice control
as much as possible without compromising public safety.
3.3.2 UAAs and Other Studies
RPBCWD has conducted several excellent UAAs and valuable studies for several water resources in the
city. Three UAAs were updated in 2013. Short descriptions of findings are provided below. In addition A
UAA for Rice Marsh Lake and Lake Riley was completed in 2016. Furthermore, the District implemented
the Creek Restoration Action Strategy study which includes both Bluff and Riley Creeks. The Upper Riley
Creek Sediment Source Assessment was also performed February 2017. The District also conducted a
beyond Atlas 14 floodplain evaluation. More detail for each study and assessment is available from the
Watershed District (http://www.rpbcwd.org/resources/).
Lake Susan. Lake Susan is a shallow, 88 acre lake. Nearly all the surface area is less than 15 feet deep,
shallow enough to be almost entirely dominated by rooted aquatic vegetation. Water quality is variable,
some years approaching state water quality standards for shallow lakes and some years worse, but on
average, the lake does not meet those standards. The Riley-Purgatory-Bluff Creek Management Plan
classified Lake Susan as a deep lake, and water quality falls short of deep lake goals.
Invasive aquatic vegetation has been an issue in Lake Susan for many years. Curly-leaf pondweed and
Eurasian watermilfoil present the greatest threat to the lake. The University of Minnesota has been
working to manage the rough fish population in the lake while also trying to reestablish native aquatic
vegetation.
Modeling completed for the UAA update estimated the amount of nutrient loading from the watershed
and from internal and other sources. The north subwatershed, where there are developed areas with
little or no water quality treatment, is the largest source of load to the lake. In the south subwatershed,
a large wetland in Lake Susan Hills West Park is a likely exporter of phosphorus. Lake Susan also
experiences high sediment loading.
Total Phosphorus (TP) load to Lake Susan needs to be reduced by 182 pounds per year, or about 25
percent, to meet the shallow lake standard. The UAA identified some pond enhancements and a
City of Chanhassen 2040 Comprehensive Plan339
Page | 3-4
restoration of the identified wetland in Lake Susan Hills Park followed by a lake alum treatment to seal
bottom sediments as potential actions to achieve that goal.
Lake Lucy and Lake Ann. Water quality in Lake Lucy and Lake Ann has been fairly stable—neither
degrading nor improving—in recent years. Lake Lucy currently meets the MPCA shallow lake water
quality standards; however, excess phosphorus results in algal blooms and reduced water clarity that
does not meet the RPBCWD’s goals. The annual phosphorus loading to Lake Lucy, based on the 2012
water year, indicates nearly half of the phosphorus load to the lake is from watershed runoff. Since the
watershed to Lake Lucy has many ponds and wetlands that settle out particulates, much of the
phosphorus that reaches Lake Lucy is in the soluble, or non-settleable, form that is readily available for
algal uptake. The other primary contributions of phosphorus are internal sources, including release from
the bottom sediments and from the dieback of Curlyleaf pondweed.
While Lake Ann is currently meeting both the RPBCWD and MPCA water quality goals, the release of
phosphorus from the lake sediments appears to lead to periodic blue-green algal blooms suspended
below the water surface. During the 2012 water year, more than half of the phosphorus load to Lake
Ann came from internal sources, primarily the release from the bottom sediments. Approximately
30 percent of the phosphorus load was from the Lake Ann watershed and discharge from Lake Lucy.
Because the lakes currently meet state water quality standards, no specific phosphorus load reductions
have been identified. However, to meet Watershed District goals, improve water clarity, and reduce the
incidence and severity of algal blooming, the UAA identified a number of management actions. These
include: implementing stormwater volume abstraction rules as portions of the watershed develop or
redevelop; maximizing the treatment of watershed runoff such as iron-enhanced sand filter pond
benches or the use of spent lime treatments to remove soluble phosphorus; curly-leaf pondweed
treatment in Lake Lucy; and a whole-lake alum treatment in Lake Ann to help control internal
phosphorus load.
3.4 PROBLEMS AND ISSUES
Local water management problems, issues, and opportunities were identified by reviewing:
•Statutory requirements for Local Water Management Plans
•Lake inventory data
•Lake UAAs and stream TMDLs
•Input solicited from the public, the Environmental Commission, city staff, and state and local
agency staff
Once the problems and issues were identified staff identified and prioritized potential solutions to help
the City of Chanhassen accomplish the goals of this Plan. This section presents those items evaluated to
develop the proposed improvements and management studies summarized in the Implementation Plan.
Table 3.2. Problems, issues, and opportunities.
Water Quality
Conditions
•Lakes and streams are listed on the Clean Water Act Section 303(d) TMDL List of
Impaired Waters.
•Nonpoint source pollution reduction is necessary through maintenance practices
such as street sweeping, sump manhole cleaning, and pond inspections.
City of Chanhassen 2040 Comprehensive Plan340
Page | 3-5
Drainage and
Flooding
•Near stream gullies and escarpments should be addressed to control sediment
deposition into surface waters and to protect property and infrastructure. There
are ongoing opportunities to work with the WMOs to address gully erosion
•Subsurface drainage causing icing on public streets and pedestrian pathways.
Regulatory
Requirements and
Operational Policies
•Atlas 14 updated precipitation frequency data is available for adoption.
•Approaches such as Minimal Impact Development and Integrated Management
Practices are available to reduce the public expenditures necessary to control
runoff and protect and improve water quality.
•The city’s approved NPDES permit and SWPPP requires ordinance revisions and
operating program enhancements.
•City goals, policies and ordinances to help protect natural resources may need
review and refinement.
Water-Based
Recreation Needs
•Water quality should be protected and improved to protect and enhance
recreational opportunities.
•Control of aquatic invasive species (AIS) is of growing concern.
Maintenance
Requirements
•BMP maintenance and repair requirements have been identified during NPDES
inspections, including restoration of storage capacity, repair of erosion, and
prevention of future problems.
•Street sweeping, sump manhole cleaning, and BMP inspections are necessary on an
ongoing basis to help reduce nonpoint source pollutant loads.
Education and
Outreach
•Education and outreach efforts could be expanded with a focus on targeted groups
with new and expanded educational opportunities. Continuing to build and grow
education opportunities with CCWMO to improve efficiency and reduce duplication
of efforts
Financial Resources •Financial resources are limited, requiring that projects be prioritized.
Groundwater
Protection
•The LWMP should be coordinated with the Wellhead Protection Program so that
policies that encourage infiltration and groundwater recharge are consistent with
the policies to protect sensitive areas and groundwater supply recharge areas.
•Seminary Fen is a rare calcareous fen and Assumption Creek is a trout stream, both
of which are dependent on groundwater.
Collaboration
Opportunities
•There are opportunities for collaboration with other agencies such as the WMOs,
the county, and state agencies to leverage expertise and resources to finance and
construct improvements.
3.4.1 2006 SWMP Priority Issues
The city’s 2006 Surface Water Management Plan identified a number of potential projects and activities
to address the then-current problems and issues and to help achieve that Plan’s goals. The highest
priority were set forth in Table 45 of that Plan. These included seven structural practices, two ordinance
updates, and some inspection and record keeping updates. Most of these high priority actions have
been completed.
City of Chanhassen 2040 Comprehensive Plan341
Page | 4-1
4.0 Goals and Policies
This section of the Plan outlines goals and policies guiding surface water management in the City of
Chanhassen. A goal is a desired end toward which surface water management efforts are directed. Each
goal has several corresponding policies that form the governing principals that will be followed to
achieve the goals. Table 4.1 summarizes the six water resources management goals. The six goals and
the corresponding policies are presented and discussed in more detail in the following pages.
Table 4.1. Water resources management goals.
Goal
Number Goal Area Goal Statement
1 Water Quantity Promote abstraction through infiltration, reuse and other methods
where practicable to do so to provide flood protection, ground water
recharge and improved water quality.
2 Water Quality Achieve water quality standards in lakes, streams, and wetlands
consistent with their designated uses and established classifications.
3 Wetlands Protect and rehabilitate wetlands to maintain or improve their function
and value.
4 Groundwater Prevent contamination of the aquifers and promote groundwater
recharge to maintain base flows in streams and wetlands.
5 Regulatory
Responsibility
Maintain primary responsibility for managing water resources at the
local level and continue coordination and cooperation with other
agencies and organizations.
6 Public Education and
Participation
Cultivate an environmentally literate public to promote an active
community role in sustainable management of water resources.
4.1 GOALS AND POLICIES
Water Quantity
Development and changes in land use that result in additional impervious surface will result in a
corresponding increase in stormwater runoff rates and volumes. This increase can cause flooding and
erosion issues in the downstream system. It is important to control these increased runoff rates and
volumes in order to ensure reduction of flooding in the downstream system and to control the potential
effects of erosive flows on streams and waterways.
Storm sewer design within the City of Chanhassen has been largely based upon the precipitation
frequency estimates published in the Weather Bureau’s Technical Paper Number 40 (“TP 40”), Rainfall
Frequency Atlas of the United States for Durations from 30 Minutes to 24 Hours and Return Periods from
1 to 100 years (Hershfield 1961). In April 2013, the National Oceanic and Atmospheric Administration
(NOAA) published Atlas 14, Precipitation – Frequency Atlas of the United States, Volume 8 Version 2.0 to
replace TP 40. Atlas 14 used a much more robust data set over a much longer time span then was used
for TP 40. While the 2-year average return interval and the 10-year average return interval remained
relatively unchanged, the 100-year amount increased by 1.38 inches or 23% over the previous estimate
City of Chanhassen 2040 Comprehensive Plan342
Page | 4-2
(Table 4.2). The longer period of record used in developing Atlas 14 allowed for a more statistically
accurate estimate of the less frequent events.
Table 4.2. Comparison of TP 40 to Atlas 14 event depths.
Publication 2-Year, 24 Hour 10-Year, 24 Hour 100-Year, 24 Hour
TP 40 2.8” 4.2” 6.0”
Atlas 14 2.87” 4.27” 7.38”
Even though we now know to design to greater depths for certain events, the city’s infrastructure has
generally performed very well. However, there have been a few instances where the existing
infrastructure was inadequate to accommodate the runoff volumes and/or rates. The city experienced
large storm events in 2005, 2009, and 2014. The first 2005 large event occurred on September 3 and 4
and totaled approximately 5.55 inches of rainfall. The second occurred on October 4 and 5, 2005, and
totaled approximately 4.61 inches of rainfall. From June 19 through June 20, 2014, the Chanhassen area
received approximately 6.23 inches of rainfall. That June Chanhassen received 12.79 inches of rainfall
after a wetter than average April and May.
While significant damages did not occur from these events, a few areas were subject to high water
levels and short-term flooding of streets. Lotus Lake, Lake Riley and Lake Minnewashta all experienced
extended high water levels. Residents on these lakes experienced submerged docks and some shoreline
erosion damage. Users were subject to the city’s emergency slow/no-wake restrictions for a period of
about 15 days. Looking at opportunities to reduce the extent and/or duration of these high water levels
is one of the key water quantity issues for the city. Because the lake discharges to Purgatory Creek, the
solution is not a simple one. Coordination with RPBCWD, Lotus Lake area residents and the potentially
impacted property owners downstream will be a critical step in developing a long term solution that
does not push the problem downstream.
Another issue that was discovered during the large event of 2005 is the lack of emergency overflows
and flow paths in some areas of the city. Ultimately, the city’s focus is to operate and maintain the
system so that it continues to function in the way it is intended, and provides flood protection for
adjacent properties. During review of storm water management plans, it is important for city staff to
review the location of emergency overflow paths for storm water infrastructure in new developments.
In recent years, there has been a paradigm shift in water quantity management. The strategy today is to
where possible manage stormwater where it falls, as exemplified by the State of Minnesota’s Minimal
Impact Design Standards (MIDS). The emphasis is on reducing the volume of runoff discharged to
downstream resources through abstraction, or the permanent retention of runoff on a site through
structures and practices such as infiltration, evapotranspiration and capture and reuse. This abstraction
can help mitigate the effects of larger storm events. Abstraction has other benefits as well, including
minimizing and reducing the amount of pollution reaching our lakes, rivers and streams and recharging
groundwater resources.
A Flood Hazard Boundary Map dated January 1979 was completed for the City of Chanhassen, which
identifies the entire city as a No Special Flood Hazard Area or Zone C. The Flood Insurance Study for
Carver County is being updated as part of the FEMA Map Modernization Program. Updated maps are
expected to be published in December 2018. Maps are available from the FEMA website,
www.fema.gov, available at City Hall or from the respective WMO.
City of Chanhassen 2040 Comprehensive Plan343
Page | 4-3
Goal 1.Promote abstraction through infiltration, reuse and other methods where practicable to
do so to provide flood protection, ground water recharge and improved water quality.
Policy 1.1.Require all developments to construct stormwater best management practices, improve
existing practices, and/or contribute to the construction or improvement of a regional
facility for the purpose of reducing peak flows and runoff volume generated by the
subject development.
Policy 1.2.Require all development and redevelopment projects to demonstrate no net increase in
the annual runoff water volume discharged from the site compared to pre-development
conditions.
Policy 1.3.Creative and innovative green site design and Best Management Practices, including
infiltration systems and stormwater reuse, will be the preferred practice unless site
limitations such as soil conditions, depth to groundwater, and safety preclude the use of
these practices.
Policy 1.4.Continue to stringently enforce lot coverage requirements set forth in City Code and
development contracts.
Policy 1.5.Establish and maintain overflow routes for ponds and low areas to provide relief during
storm conditions that exceed design conditions.
Policy 1.6.Where volume reduction is infeasible and detention ponds are necessary, regional
ponding areas, as opposed to individual on-site ponds, should be used to reduce
flooding, to control discharge rates, and to provide necessary storage volumes as
indicated in this Plan.
Policy 1.7. When areas are developed, redeveloped, and as infrastructure is replaced, stormwater
facilities should be built and/or upgraded to provide or improve flood management and
water quality.
Policy 1.8. Encourage the development of new and improvement of existing ponds located
upstream of priority water bodies.
Policy 1.9. Permanently protect surface water impoundments and drainage systems by requiring
the dedication of land and/or protective easements as required.
Policy 1.10. Design, operate and maintain newly constructed storm water facilities in accordance
with this Plan and NPDES MS4 permit requirements.
Policy 1.11. Manage floodplain activities in accordance with all city, state, and federal regulations.
Policy 1.12. Require building elevations to provide at least 3 feet of freeboard adjacent to ponding
areas and floodplains for all development and redevelopment or when drainage
facilities are constructed for an area.
Policy 1.13. Preserve existing water storage below 100-year flood elevations.
Policy 1.14. Continue management and development of public and private stormwater
infrastructure as separate systems.
Policy 1.15. The Water Resources Department manages public surface water resources identified in
the LWMP and NPDES MS4 permit. Drainage, seeps, and springs on or between single
family private parcels is not managed unless specifically identified in the LWMP,
NPDES permit, or city ordinance.
City of Chanhassen 2040 Comprehensive Plan344
Page | 4-4
Policy 1.16.Require development and redevelopment stormwater management incorporate the
protection of existing and native plant and forest communities.
Policy 1.17.Develop a tree preservation and native habitat protection credit consistent with the
MCWD credit
Policy 1.18.Require development and redevelopment projects and plans incorporate wildlife
connectivity opportunities
Water Quality
The City of Chanhassen seeks to maintain and improve the water quality in its lakes, streams and
wetlands to meet or better the State of Minnesota surface water quality standards for lakes and
streams. There are many potential sources of water pollution that can negatively impact public safety
and the enjoyment of these resources. Stormwater runoff can convey phosphorus, chloride, sediment,
oils, debris, and bacteria to downstream waters, increasing algal blooms, reducing water clarity, and
impacting fish and other aquatic communities. Excessive volumes and rates of stormwater runoff
discharged into channels and streams can erode streambanks, causing additional water quality impacts.
One of the city’s chief strategies for achieving its water quality goals is to require development and
redevelopment to provide stormwater quality treatment through abstraction of 1.1 inch of runoff from
impervious surfaces, or if that is infeasible, to provide treatment by some other means. Other strategies
include better management of construction site erosion control measures, disconnecting and reducing
the level of impervious cover, reducing the extent of managed lawn areas and replacing them with
native vegetation, reducing stream bank erosion, and practicing good housekeeping practices, such as
removing leaves from streets and storm drains and limiting the use of phosphorus fertilizers.
Goal 2.Achieve water quality standards in lakes, streams, and wetlands consistent with their
designated uses and established classifications.
Policy 2.1. Manage each water body in the city’s surface water system to meet state, local, and
federal water quality standards.
Policy 2.2. Require that development and redevelopment projects demonstrate no net increase in
the annual mass of total suspended solids (TSS), total phosphorous (TP) from the site
compared to pre-development conditions.
Policy 2.3. Require owners of development or redevelopment projects to provide on-site volume
reduction or treatment or, where volume reduction is infeasible, contribute to the
construction or improvement of a regional facility.
Policy 2.4.Establish and implement on-going programs for property owners, local leaders, and
those who live, work and play in the city designed to promote active stewardship of
water resources. Develop and maintain a public education program to promote
reduction of nutrient and sediment loading to water bodies.
Policy 2.5. Continue to monitor long-term water quality trends on prioritized water bodies.
Policy 2.6. Develop and implement a priority ranking scheme to focus management activities and
capital improvements. Update priorities annually with a 5-year horizon.
Policy 2.7. Evaluate the progress of the surface water management program on an annual basis in
conjunction with the NPDES MS4 annual report.
City of Chanhassen 2040 Comprehensive Plan345
Page | 4-5
Policy 2.8. The city may require higher water quality standards in areas draining to an Impaired or
Special Water.
Policy 2.9. The city will lead by example by following the standards of this Plan and implementing
BMPs to provide pollution prevention and water quality treatment on city-initiated
projects.
Policy 2.10. All vegetative surfaces must utilize native vegetative cover, deep rooted low mow/no
mow/turf alternatives, or approved landscape plantings. Landscape plantings include
woody vegetation, annual and perennial forbs, ornamental grasses, fruit/vegetable
gardens, and mulch
Policy 2.11. Prohibit the discharge of foreign material into the storm water system. Such material
should include, but not be limited to, waste oil, paint, grass clippings, leaves,
commercial fertilizers, trash, construction debris, and miscellaneous chemicals.
Policy 2.12. Continue implementing a spill response program for the city personnel to prevent
discharge of spilled materials into the storm sewer system.
Policy 2.13. Continue to implement the erosion and sediment control policies and the construction
site inspection program to ensure reduction of water quality impacts from lack of
erosion and sediment control.
Policy 2.14. Protect shorelands and water resources. All properties are required to have native
vegetated buffer adjacent to wetlands, storm ponds, and water resources. Non-
conforming properties, and lots of record shall be brought into compliance when
applying for permits or variances to improve the property. Non-conforming buffers
should attempt to meet regulatory requirements whenever possible. The minimum non-
conforming buffer width shall be 10’.
Policy 2.15.Maintain a shoreland ordinance consistent with DNR requirements and
recommendations to promote and encourage shoreland protection.
Policy 2.16.Develop a Vegetation Management Plan. Ordinances and policies will be updated based
on the goals and recommendations of the plan.
Wetlands
The City of Chanhassen serves as the Local Government Unit (LGU) for the purposes of administering the
State of Minnesota’s Wetland Conservation Act (WCA). The city’s Wetland Protection Ordinance sets
forth standards for the protection of wetlands, including wetland buffers, setbacks, and mitigation of
unavoidable impacts. The policies and strategies set forth in this Plan will apply to all property within the
city. Any wetland habitat will be subject to these management policies, as well as the rules and
requirements of the Wetland Conservation Act.
Goal 3.Protect and rehabilitate wetlands to maintain or improve their function and value.
Policy 3.1. Continue to act as the responsible Local Government Unit (LGU) for administration
of the Minnesota Wetland Conservation Act (WCA) for wetland impacts in the city.
Policy 3.2. Maintain an official wetlands map that classifies wetlands by function and value and
periodically update the wetland inventory data and the wetland management
classifications.
City of Chanhassen 2040 Comprehensive Plan346
Page | 4-6
Policy 3.3. Update the city’s Wetland Protection Ordinance as necessary to maintain consistency
with state and watershed district requirements.
Policy 3.4. Promote stewardship of wetlands on private property.
Policy 3.5. Ensure administrative costs are reasonable and sufficient to cover administration of
WCA. Administrative fee will be an average of neighboring LGUs that administer the
WCA.
Policy 3.6. Improve historic wetlands through pre-treatment and restoration activates when
practical to do so, and in conjunction with street improvement and redevelopment
projects.
Policy 3.7. Prioritize the protection the Seminary Fen and, unique natural resources during
development and redevelopment.
Policy 3.8. Allow natural wetland systems to function within their existing and historic boundaries
without interference or removal of non-invasive plant and wildlife species.
Policy 3.9. Impacts to, or created by, existing, non-invasive, vegetation and wildlife caused by local
climate impact, natural behavior, or approved development are considered
natural wetland functions.
Groundwater
The city’s role in managing groundwater resources is limited in scope. There are actions the city can
take to prevent or minimize impacts to groundwater quality. Groundwater and surface waters
interact, and streams and wetlands and, to a lesser extent, lakes are reliant on groundwater
contributions to maintain stream baseflow and wetland hydrology. The city’s primary strategies in
groundwater management are to encourage infiltration of stormwater to help recharge surficial
groundwater and to encourage water reuse and conservation to reduce consumption and protect the
water supply.
Goal 4.Prevent contamination of the aquifers and promote groundwater recharge to maintain
base flows in streams and wetlands.
Policy 4.1. Continue implementation of the City of Chanhassen Wellhead Protection Plan and
implement Carver County Groundwater Plan 2016.
Policy 4.2. Cooperate with the Minnesota Department of Health (MDH), Carver County, the
Department of Natural Resources, and other agencies to periodically assess the
vulnerability of groundwater used for drinking water supplies.
Policy 4.3. Promote infiltration of stormwater and resulting groundwater recharge where it is
feasible and does not pose a threat to groundwater quality, in accordance with the
Minnesota Department of Health’s Evaluating Proposed Storm Water Infiltration
Projects in Vulnerable Wellhead Protection Areas.
Policy 4.4.Promote proper well abandonment.
Regulatory Responsibility
City of Chanhassen 2040 Comprehensive Plan347
Page | 4-7
The city assumes the role of permitting all land alteration activities summarized in table 4.3 and
enforcing the standards and policies set forth by the Plan. Riley Purgatory Bluff Creek Watershed District
(RPBCWD) also reviews and permits on any proposed land alteration under their rules within the
RPBCWD. Minnehaha Creek Watershed District (MCWD) permits for projects that include land
alteration, floodplain alteration, dredging, shoreline and streambank improvement, and stream and lake
crossings. Lower Minnesota River Watershed District reviews alterations to land within the Minnesota
River valley. Carver County Water Management Organization reviews and permits land altering projects
in the WMO. The city is the LGU for the Wetland Conservation Act, and assumes the role of permitting
all wetland impacts.
The Minnesota Department of Natural Resources has authority over issues relating to water and
wetlands designated as State Protected Wetlands and Waters. The U.S. Army Corps of Engineers has
authority relating to all wetlands identified by the U.S. Fish and Wildlife Service’s National Wetland
Inventory.
The Minnesota Department of Health has regulatory authority over groundwater issues within the city.
Carver County has adopted a Groundwater Plan (2016). Erosion control falls under several jurisdictions
including the city, the watershed districts, and the MPCA. The MPCA also has regulatory authority over
individual septic systems within the city limits.
Table 4.3. Agencies with regulatory authority.
Rule Chanhassen CCWMO LMnRWD MCWD RPBCWD
Dredging And Sediment Removal No No NA Yes Yes
Erosion Prevention & Sediment
Control Yes No NA No Yes
Floodplain Management Yes No NA Yes Yes
Shoreline & Streambank Stabilization No No NA Yes Yes
Stormwater Management Yes No NA No Yes
Water Appropriations No No NA No Yes
Waterbody Crossings No No NA Yes Yes
Wetland & Stream Buffers Yes No NA No Yes
MOU = Memorandum of Understanding
Goal 5.Maintain primary responsibility for managing water resources at the local level and
continue coordination and cooperation with other agencies and organizations.
Policy 5.1. Adopt policies consistent with the most stringent local watershed authorities’
management plans to the extent practicable.
Policy 5.2. Enter into memorandum of understanding where maintaining consistency with local
watershed authorities’ plans would otherwise be counter to city’s overall goals.
Policy 5.3. This plan and all subsequent amendments will be consistent with the plans of regulatory
agencies.
Policy 5.4. This plan will be amended as necessary to remain current.
Policy 5.5. Coordinate projects and information with government agencies; i.e. MnDOT, Carver and
Hennepin Counties, Department of Natural Resources, Watershed Districts, and Water
Management Organizations.
City of Chanhassen 2040 Comprehensive Plan348
Page | 4-8
Public Education and Participation
The public education and participation goals and policies recognize that people want to be involved in
decisions that affect the water resources in their community. The city seeks to create opportunities
for the public to participate in information gathering and decision-making. Public education and
participation activities are also requirements of the National Pollutant Discharge Elimination System
(NPDES) Permit.
Goal 6.Cultivate an environmentally literate public to promote an active community role in
sustainable management of water resources.
Policy 6.1. The city will continue to provide opportunities for public involvement (e.g.,
neighborhood meetings, public hearings, mailed notices, etc.) for significant water
resource decisions or projects.
Policy 6.2. The city will coordinate and consult with appropriate city commissions and committees
on surface water issues.
Policy 6.3. The city will communicate with lake associations and other appropriate civic and citizen
groups.
Policy 6.4. The city will develop an Education and Outreach Plan, actively implement the current
educational programs, and work to develop and implement new education programs
and activities related to water resources.
Policy 6.5. The city will cooperate with other agencies and encourage establishment of model
interpretative sites for public education like the stormwater practices at the Landscape
Arboretum.
Policy 6.6. Continue to remain in compliance with the NPDES Phase II MS4 permit with respect to
public education and involvement.
Policy 6.7. Promote the installation of low mow/no mow turf, turf alternatives, and restoration of
native vegetation on all public and private property within the city. Update ordinances
as needed to reflect policy.
Policy 6.8. Promote safety education in an effort to promote the co-existence of commercial and
recreational navigation on the Lower Minnesota River.
Policy 6.9. Prioritize partnership opportunities with CCWMO to improve and expand education and
outreach programs and goals.
City of Chanhassen 2040 Comprehensive Plan349
Page | 5-1
5.0 Implementation Plan
The City of Chanhassen will implement both management programs and capital projects to achieve the
goals and policies set forth in this Plan. These actions address the problems and issues identified here as
well as NPDES and TMDL requirements and agency and watershed expectations. The following sections
describe those actions, which as summarized in Tables 5.2 and 5.3. Each year, the city will review
progress and resources, and these implementation actions may be reviewed and updated based on
changing conditions or requirements. If necessary, this Plan may be amended in accordance with the
procedure set forth in Section 6.0.
5.1 PERMITTING AND ENFORCEMENT
Numerous local, state, and federal agencies regulate water resources. However, the primary regulators
are the City of Chanhassen, the four watershed management organizations within Chanhassen; the
Minnesota Department of Natural Resources (MDNR); and the Minnesota Pollution Control Agency
(MPCA). These regulations are discussed in Section 2.0 Regulatory Framework.
5.1.1 Current Ordinances and Potential Revisions
The City of Chanhassen has enacted numerous policies and ordinances regulating and managing water
resources. These are described in Section 2.1 above. In its NPDES stormwater permit application, the
city agreed to within one year of permit approval adopt ordinance revisions as necessary to meet permit
requirements.
It is the city’s desire to reduce administrative and regulatory burden while staying protective of our
water and natural resources. The city intends to exercise sole regulatory authority over development
and redevelopment projects requiring stormwater, wetland, floodplain, or erosion control review and
approval, and will work with the WMOs to adopt Memoranda of Understanding (MOU). The city will
continue to ensure submission of applications for permits under those WMO rules, and all variances, for
which the city does not have authority, are submitted to the WMOs for review and approval. This
process will be assured through the implementation of a new water resource permit process developed
in collaboration with the WMOs.
In addition to amending its official controls, the city will follow the framework and scope for each WMO
required to adopt an MOU. Specifically, RPBCWD requires the MOU details the scope of each entity’s
exercise of regulatory authority (i.e., who will regulate what) for presentation to the City Council and
Board of Managers for approval. The MOU also will establish a process and schedule for exchanging
progress reports, the city’s submission of permitting information to the District and regular meeting to
ensure water-resources management concerns and projects are pursued via the most effective and cost-
efficient route possible. The MOU also will provide procedures and a timeline for the District’s
reengagement of all of its regulatory authority if the city is found not to have adopted the necessary
official controls or implemented a complete and effective regulatory program.
Additional regulatory revisions are necessary to bring the ordinances into conformance with the
requirements of the watershed districts in the city (Table 5.1). The city will undertake these ordinance
revisions within six months after adoption of this Plan. It is expected that where the requirements of the
City of Chanhassen 2040 Comprehensive Plan350
Page | 5-2
individual watershed districts differ, the city will adopt the most stringent of the requirements for
application citywide. The most stringent requirements the city will adopt are highlighted in Table 5.1.
The city will work with the WMOs as it considers regulatory revisions and permit review processes and
procedures to ensure that they are consistent with WMO requirements. The city commits to updating its
ordinances as necessary and required within one year after receiving notification that a WMO has
significantly revised its rules and standards.
City of Chanhassen 2040 Comprehensive Plan351
Page | 5-3
Table 5.1. Regulatory requirements of various agencies compared to Chanhassen current ordinances.
Note: Highlight indicates the standards the City expects to adopt following approval of the Plan.
Standard Chanhassen NPDES General Permit NPDES Construction Permit
Carver County WMO
Plan: October 26, 2010
Rules: 10/15/16
Riley- Purgatory –Bluff Cr WD
Plan: January 26, 2011
Rules: Effective 1/1/15
Lower Minnesota River WD
Plan: December 14, 2011
Rules: Cities; new standards
pending 9/17
Minnehaha Creek WD
Plan: July 5, 2007
Rules: 6/6/14
Threshold: single family
residential new development
N/A Disturb >1 acre of land, or
part of common development
>1 acre
Disturb >1 acre of land, or
part of common development
>1 acre
Create 1> impervious or
>10,000 sf in sensitive areas
a. Land-disturbing activities
that will disturb 50 cubic yards
or more of earth;
b. Land-disturbing activities
that will disturb 5,000 square
feet or more of surface area
or vegetation; or
c. Subdivision of a parcel into
three or more residential lots.
Disturb >1 acre of land
Pending Draft: within the
HVRA Overlay, create >10,000
sq ft new impervious area
≥1 acre where more than 20%
of site is or will be impervious
Threshold: non-residential
new development
N/A Disturb >1 acre of land, or
part of common development
>1 acre
Disturb >1 acre of land, or
part of common development
>1 acre
Create 1> impervious or
>10,000 sf in sensitive areas
a. Land-disturbing activities
that will disturb 50 cubic yards
or more of earth;
b. Land-disturbing activities
that will disturb 5,000 square
feet or more of surface area
or vegetation
Disturb >1 acre of land
Pending Draft: within the
HVRA Overlay, create >10,000
sq ft new impervious area
≥1 acre where more than 20%
of site is or will be impervious
Threshold: single family
residential redevelopment
N/A Disturb >1 acre of land, or
part of common development
>1 acre
Disturb >1 acre of land, or
part of common development
>1 acre
Additions: Create 1> acre
impervious or >10,000 sf in
sensitive areas, for new
impervious
Tear downs: Create >1 acre
impervious or >10,000 sf in
sensitive areas, for all
impervious created by project;
Redevelopments that reduce
imperviousness by 10% are
exempt from rate, volume,
and WQ reqs
Same as above, except where
redevelopment of more than
50% of site or that increases
impervious by more than 50%,
applies to entire site; less than
50% of site, applies only to
disturbed area/new
impervious
Disturb >1 acre of land
Pending Draft: within the
HVRA Overlay, create >10,000
sq ft new impervious area
≤1 acre; requirements vary by
size, change in
imperviousness, and %
disturbance
Threshold: non-residential
redevelopment
N/A Disturb >1 acre of land, or
part of common development
>1 acre
Disturb >1 acre of land, or
part of common development
>1 acre
Additions: Create 1> acre
impervious or >10,000 sf in
sensitive areas, for new
impervious
Tear downs: Create >1 acre
impervious or >10,000 sf in
sensitive areas, for all
impervious created by project;
Redevelopments that reduce
imperviousness by 10% are
exempt from rate, volume,
and WQ reqs
Same as above, except where
redevelopment of more than
50% of site or that increases
impervious by more than 50%,
applies to entire site; less than
50% of site, applies only to
disturbed area/new
impervious
Disturb >1 acre of land
Pending Draft: within the
HVRA Overlay, create >10,000
sq ft new impervious area
>1 acre; requirements vary of
< or > 40% site disturbance
City of Chanhassen 2040 Comprehensive Plan352
Page | 5-4
Standard Chanhassen NPDES General Permit NPDES Construction Permit
Carver County WMO
Plan: October 26, 2010
Rules: 10/15/16
Riley- Purgatory –Bluff Cr WD
Plan: January 26, 2011
Rules: Effective 1/1/15
Lower Minnesota River WD
Plan: December 14, 2011
Rules: Cities; new standards
pending 9/17
Minnehaha Creek WD
Plan: July 5, 2007
Rules: 6/6/14
Threshold: grading and erosion
control
Disturb>5,000 sf, excavate or
place >50 cy fill, any
disturbance on “highly
erodible” land or land in the
Bluff Creek Overlay District, or
with any earthwork permit
Disturb >1 acre of land, or
part of common development
>1 acre
Disturb >1 acre of land, or
part of common development
>1 acre
>1 acre construction activity;
<1 acres in sensitive areas or
part of common development
a. Land-disturbing activities
that will disturb 50 cubic yards
or more of earth,
b. Land-disturbing activities
that will disturb 5,000 square
feet or more of surface area
or vegetation
As required by the General
Permit for Construction
Pending Draft: Disturb >1 acre
of land, or within the HVRA
Overlay District, disturb more
than 5,000 sq feet or disturb
50 cubic yards or more of
earth,
All land disturbing activity
except agriculture and
disturbances of less than
5,000 sq ft moving less than
50 cu yd
Water quality: new
development
Whichever is most restrictive:
meet NPDES construction
permit; NURP criteria (90%
TSS and 60% TP; or special
requirements for discharges
to “Preserve” waters
No net increase in TP or TSS
annual load
Wet pond with 1,800 cu ft
dead storage per contributing
acre and live storage of 1” of
runoff from new impervious
surface
90% removal of TP and TSS
from the 1.05” event
Provide for at least 60%
removal of TP and 90%
removal of TSS from all runoff
from site
Treatment as required by the
General Permit for
Construction; NURP pond
designs apply
Draft pending: No net
increase in TP or TSS. Within
HVRA 60% decrease in TP and
80% TSS from
predevelopment condition
No net increase in TP, except
where land use was row
crop/feedlot, must be
modeled as if meadow
Water quality: redevelopment Whichever is most restrictive:
meet NPDES construction
permit; NURP criteria (90%
TSS and 60% TP; or special
requirements for discharges
to “Preserve” waters
Decrease in TP and TSS annual
load
Wet pond with 1,800 cu ft
dead storage per contributing
acre and live storage of 1” of
runoff from new impervious
surface
90% removal of TP and TSS
from the 1.05” event
Provide for at least 60%
removal of TP and 90%
removal of TSS from all runoff
from site
Treatment as required by the
General Permit for
Construction; NURP pond
designs apply
Draft pending: No net
increase in TP or TSS. Within
HVRA decrease in TP and TSS
from predevelopment
condition
Varies based on size and
whether impervious is
increased or decreased
Rate control No increase over 1- or 2-, 10-,
and 100-year rates
No specific requirement No more than 5.66 cfs per
acre pond surface area
No increase over 2-, 10-, and
100-year rates and 10-day
snowmelt;
Extended detention for sites
discharging directly to
streams: 50% reduction of 2-
year discharge from existing
No increase over 2-, 10-, and
100-year Atlas 14 Nested
Distribution rates
No increase over 1-or 2-, 10-,
or 100-year rates Pending
draft: using Atlas 14 Nested
Distribution rates
No increase over 1-, 10-, and
100-year rates, except where
land use was row
crop/feedlot, must be
modeled as if meadow
Infiltration: new development Discharging to special waters:
Infiltration of excess volume
over pre-development
volume, up to 2-yr, 24-hour
event
Any grading permit: Soil
amendment ripped into
existing soil materials to a
depth of ten inches on the site
No net increase in annual
runoff volume
If more than 1 acre of new
impervious, infiltrate/abstract
1” from new impervious
surface
Abstraction of 1.0” runoff
from impervious surface (0.5”
if site is restricted)
1.1” abstraction from all
impervious surface
0.5” runoff from new
impervious surface
Pending Draft: sites that
create >1 acre new
impervious abstract 1” from
all impervious. Within HVRA,
sites that create >10,000 sf
new impervious abstract 1.1”
1” from impervious surface.
Where 1” infeasible, must do
at least 0.5” plus additional TP
reduction
City of Chanhassen 2040 Comprehensive Plan353
Page | 5-5
Standard Chanhassen NPDES General Permit NPDES Construction Permit
Carver County WMO
Plan: October 26, 2010
Rules: 10/15/16
Riley- Purgatory –Bluff Cr WD
Plan: January 26, 2011
Rules: Effective 1/1/15
Lower Minnesota River WD
Plan: December 14, 2011
Rules: Cities; new standards
pending 9/17
Minnehaha Creek WD
Plan: July 5, 2007
Rules: 6/6/14
Infiltration: redevelopment Discharging to special waters:
Infiltration of excess volume
over pre-development
volume, up to 2-yr, 24-hour
event
Any grading permit: Soil
amendment ripped into
existing soil materials to a
depth of ten inches on the site
Decrease in annual runoff
volume
If more than 1 acre of new
impervious, infiltrate/abstract
1” from new impervious
surface
Abstraction of 1” runoff from
impervious surface
1.1” abstraction from all
impervious surface
0.5” runoff from new
impervious surface
Pending Draft: sites that
create >1 acre new
impervious abstract 1” from
all impervious. Within HVRA,
sites that create >10,000 sf
new impervious abstract 1.1”
1” from impervious surface.
Where 1” infeasible, must do
at least 0.5” plus additional TP
reduction
Wetland buffer ** 16.5 to 50 feet from wetlands
depending on mgmt. class;
100 feet from special water
No specific requirement 100 feet from a special water Minimum 20 feet, adjusted
based on slope, whether
runoff s directed to the buffer
or if the wetland is ranked
“high,” to a maximum 50 feet
Avg width 20 to 80 feet from
wetlands, depending on
mgmt. class; 50 feet from a
water basin; 50 feet from the
thalweg of any watercourse in
a High Risk Erosion Area, 50
feet from the centerline of a
public waters watercourse
a.<2 acres, 25’ minimum;
b. .2 acres, 25’ minimum,
average 50’
16 to 75 feet, depending on
wetland mgmt class
Linear projects No specific requirement Disturb >1 acre of land; may
be excepted from some or all
infiltration requirement if lack
sufficient right of way
Disturb >1 acre of land Projects adding 1 acre or
more of impervious (10,000 sf
in sensitive areas), for new
impervious created by project.
Reconstructs that reduce
imperviousness by 10% are
exempt from rate, volume,
and WQ reqs
If project constructs more
than 5,000 square feet of
impervious, and creates ≥1
acre new or fully
reconstructed impervious
surface. Applies only to all
new and reconstructed
impervious surface.
No specific requirement Projects creating >10,000 sq ft
new impervious surface
City of Chanhassen 2040 Comprehensive Plan354
Page | 5-6
Standard Chanhassen NPDES General Permit NPDES Construction Permit
Carver County WMO
Plan: October 26, 2010
Rules: 10/15/16
Riley- Purgatory –Bluff Cr WD
Plan: January 26, 2011
Rules: Effective 1/1/15
Lower Minnesota River WD
Plan: December 14, 2011
Rules: Cities; new standards
pending 9/17
Minnehaha Creek WD
Plan: July 5, 2007
Rules: 6/6/14
Bluff requirements No removal of vegetation and
no new impervious in the
Bluff Impact Zone (20’ from
top of bluff); new structure
setback 30 ft top of bluff, SSTS
setback 50 ft
No specific requirement No specific requirement Unknown Unknown No removal of vegetation in
the Bluff Impact Zone and
Bluff Face; new structure
setback 30 ft top of bluff, SSTS
setback 50 ft. Stormwater
infrastructure setback 50 feet
from the top of the bluff.
Approved LWP: The LGU will
demonstrate to the District in
its local water plan (LWP) that
any bluff approved for land
disturbing activity is not an
ecologically sensitive
resources. The LGU must
demonstrate that the
proposed activities on the
bluff do not: (1) impact
adjacent properties, (2) result
in unstable slope conditions,
and (3) result in the
degradation of waterbodies
from erosion, sedimentation,
flooding, and other damage.
Additional Criteria A, A-a, A-c,
A-d, B, B-a.i.1, B-a.i.2, and C.
Pending Draft: establishes
High Value Resources Area
(HVRA) Overlay District
No specific requirement
TP-40 or Atlas 14 TP-40 No specific requirement No specific requirement Atlas 14 Atlas 14 Cities
Pending Draft: Atlas 14
Will adopt Atlas 14 as part of
current rule revision
** No single WMO had the most stringent wetland buffers. The City will adopt the most stringent buffers across all WMOs as follows: Preserve management class = 80’ base buffer width and 67’ minimum, Manage 1 = 60’ base buffer width
and 34’ minimum, Manage 2 = 40’ base buffer width and 24’ minimum, Manage 3 = 20’ base buffer width and 16’ minimum. Seminary Fen = 100’ base buffer width and 50’ minimum. Base buffer widths will be an average for all management
classes. Principal structure setback will be 20’ for all management classes.
City of Chanhassen 2040 Comprehensive Plan355
Page | 5-7
5.1.2 NPDES Permit Implementation Requirements
Under the requirements of NPDES Phase II, the city has implemented a Storm Water Pollution
Prevention Program (SWPPP). Best Management Practices (BMPs) identified in the MPCA-approved
SWPPP are implemented on an ongoing basis. Annual activities are detailed in the city’s Annual Report
and reviewed at an annual public meeting prior to submittal of the annual report to the MPCA. More
information about the SWPPP can be found in the Surface Water Resources Section of the city’s website
(http://www.ci.chanhassen.mn.us/index.aspx?nid=1085.)
The city’s Engineering/GIS Department maintains databases and GIS mapping of stormwater and
wetland information for both public and private systems. These sources summarize pertinent
management information about BMPs, wetlands, and other water resources in the city including BMP
location, type, and responsible party. The information provided for stormwater ponding systems
includes physical condition, maintenance histories, pond elevations, watershed acreages, basin sizes,
and other as-built information where available. The city utilizes a Stormwater Asset Management
Program from WSB to rank basins based on cost/benefit, pollutant removal efficiency, and annual
inspect data. All information is being collected, updated, and integrated into the city’s general asset
management software on an ongoing basis as part of the NPDES Phase II permit requirements and
provides data and direction to prioritize maintenance. The city will work with state, federal, and local
entities to determine additional data needs and the best approach to manage the data. An Inventory of
real property owned by the city, and maps of public and private stormwater systems are included in
Appendix A. The city is committed to complete the MCWD conveyance map and inventory discussion
within 2 years of Plan adoption.
The State’s General Permit was reissued effective August 1, 2013, and the city has been issued a
reauthorized permit. The city’s SWPPP application identified a number of BMPs that the city needs to
initiate or update, such as developing certain programs, expanding record keeping, and establishing new
or modified policies. The new permit also requires revisions to the city’s ordinances requiring
stormwater management, namely adopting more stringent standards to reduce phosphorus and total
suspended sediment in stormwater runoff, limiting new volumes of stormwater runoff, public education
and staff training, illicit discharge, BMP inspection and maintenance for both public and private
stormwater BMPs.
5.2 IMPLEMENTATION PROGRAMS AND PROJECTS
5.2.1 Education and Outreach Program
The city recognizes that a critical element in reaching the long-term goals developed for this LWMP is
public education. An education and outreach plan will be developed to achieve these goals and meet
requirements of the NPDES permit. This plan will incorporate opportunities to collaborate with the four
WMOs and other organizations to maximize existing local education resources and expertise. The city
also uses various media outlets such as local news articles, city newsletters, Facebook, and the City of
Chanhassen website to educate citizens on the basics of our stormwater system, provide updates on
current actions the city is taking to monitor or improve stormwater systems, and inform residents about
opportunities to improve local water bodies through workshops, volunteer opportunities, or rebates.
City of Chanhassen 2040 Comprehensive Plan356
Page | 5-8
City events and festivals provide additional opportunities for education. High priority topics are
periodically identified for emphasis, including topics such as:
•Water resource management •Pollinators and Wildlife habitat
•Groundwater protection •Low impact and green design such as pervious pavers
•Wetlands •Pet waste control
•Native plant establishment •Leaf and grass clipping management
•Wetland, lake and pond buffers •Lawn chemical and phosphorus fertilizer usage
Adults and youth can also participate in outreach activities such as: the storm drain labelling program;
Wetland Health Evaluation Program (WHEP); park cleanup events; Citizen Assisted Lake Monitoring
program (CAMP). The City Council relies on a Planning Commission and Environmental Commission to
provide recommendations and direction on water resource topics.
The city recognizes the important value of coordination and collaboration with other agencies, and will
continue to find opportunities to improve these relationships and will utilize collaborative resources
such as WaterShed Partners, Blue Thumb, Let’s Keep it Clean, the Minnesota Stormwater Coalition, and
the CCWMO to maximize resources and message impacts. LMRWD offers a Cost Share Incentive
Program and Water Quality Restoration Program that the city will promote. Education programming
includes training for city staff, local leaders and decision makers on various water resources
management topics.
5.2.2 Monitoring Program
The city will meet with each WMO staff annually to review opportunities to coordinate data collection
and assessment to improve informed decision making. In addition the city continues to operate the
following monitoring programs:
Citizen Assisted Monitoring Program (CAMP). The City of Chanhassen partners with the Metropolitan
Council to participate in its Citizen Assisted Monitoring Program (CAMP). Volunteers collect surface
water samples from Chanhassen lakes. The samples are then sent to the Metropolitan Council to be
analyzed for the following:
•Total phosphorus (TP)
•Total Kjeldahl nitrogen (TKN)
•Chlorophyll-a (CLA)
Volunteers also gather the following information:
•Measure surface water transparency using a Secchi disc
•Record water temperature
•Record perceptions such as weather conditions
Samples are taken bi-weekly from April through October (14 sampling dates) and are sampled at the
lake's deepest open-water location. The CAMP currently monitors the following lakes:
•Lake Lucy
City of Chanhassen 2040 Comprehensive Plan357
Page | 5-9
•Lake Minnewashta
•Lake Riley
•Lake St. Joe
•Lake Susan
•Lotus Lake
Stream Health Evaluation Program (SHEP). This program gives citizens professional training on how to
evaluate a stream health based on physical assessments and bio-monitoring. Citizens evaluate physical
characteristics of stream sites, collect and identify macro-invertebrates. Citizens get hands on
opportunities to learn about stream ecosystems and assist Carver County in water quality monitoring.
Aquatic Invasive Species (AIS). AIS monitoring is coordinated through a partnership program with
CCWMO, RPBCWD, and local lake associations
5.2.3 Operations and Maintenance
The City of Chanhassen follows Best Management Practices (BMPs) in operating and maintaining its
infrastructure and facilities, consistent with its NPDES permit and this Plan. The city’s approach to
ensuring maintenance of private stormwater infrastructure for development and redevelopment
includes:
•Stormwater BMPs are required to be placed into permanent easements recorded against the
property.
•Public BMPs are required to be placed in drainage and utility easements recorded on the plat.
•All BMPs are required to have Operation and Maintenance Plans detailing maintenance
responsibilities, and recorded against the property.
•All BMPs are required to have Inspection Forms detailing inspection activities and including
identification of responsible party performing the maintenance and submitting annual
inspection reports.
•Authorization for the city to access BMPs for inspection and to perform maintenance if property
owner fails to meet requirements. Property owner is responsible for all maintenance costs
incurred by the city.
•Wetlands and water resources are to be placed into outlots during development or
redevelopment.
•Recommends BMPs receiving public or community stormwater not be placed on single family
residential lots during development or redevelopment.
•The city does not have the capacity to take on private stormwater BMP maintenance, therefore,
it is the responsibility of the property owner to operate, maintain, and inspect.
City staff and projects serve as a model for good housekeeping practices. Some specific Best
Management Practices integrated into daily activities include:
Street Sweeping. The city sweeps all streets at least annually, and sweeps more frequently in certain key
areas. Staff continuously reviews street sweeping practices to assure they are consistent with the latest
management recommendations. Some TMDLs and UAAs have identified key areas where enhanced
sweeping can provide additional nutrient and sediment removal to protect or improve lake and stream
water quality.
City of Chanhassen 2040 Comprehensive Plan358
Page | 5-10
Snow and Ice Control. Street maintenance staff use the recently-developed Winter Maintenance
Assessment Tool from the MPCA to evaluate and enhance snow and ice control practices optimizing the
application of road salt - sodium chloride – to limit chloride loading to surface waters.
BMP Inspections and Maintenance. In accordance with its NPDES permit, stormwater ponds are
inspected at least every five years for sediment accumulation and maintenance needs. The city’s BMP
Inspection and Maintenance Program ensures public and private stormwater infrastructure is inspected
and maintained to meet regulatory requirements. Private stormwater BMPs on sites over an acre that
discharge into the city’s system submit annual inspection reports, and are inspected by city staff once
every three years. The city utilizes design standard details setting forth the city’s BMP and infrastructure
design and maintenance requirements. The city is developing its Stormwater Inventory Inspection and
Maintenance Plan. This Plan includes both activities necessary to meet NPDES Phase II permit
obligations as well as general operations and maintenance activities. These include:
•BMP operation and maintenance plans
•Vegetation Management Plan
•Facilities Maintenance Plans
•Street and parking lot sweeping
•Chloride management
•Catch basin and sump inspection, cleaning, and repair.
•Sump catch basin inspection, cleaning, and repair.
•Sediment removal schedules.
•Televising, jetting, and repair of storm sewers and culverts.
•Treatment effectiveness evaluation.
•Illicit discharge detection and elimination plan
As a requirement of its NPDES permit, the city must establish Enforcement Response Procedures and
Plan Review Checklists which will be added as Appendix D and E within 6 months of Plan adoption. The
City of Chanhassen also maintains up to date GIS shapefiles containing information about water bodies,
stormwater facilities, and stormwater infrastructure.
Opportunistic BMPs. Where possible, Chanhassen will incorporate BMPs into its street and utility
infrastructure to protect and preserve its water and natural resources.
5.2.4 Capital Improvement Program
The Implementation Plan in Tables 5.2 and 5.3 details a Capital Improvement Program (CIP) of projects.
The Use Attainability Analyses (UAAs) and Total Maximum Daily Load (TMDL) studies have identified
potential actions that could help protect and improve the water quality in and enjoyment of studied
waterbodies, and some of those actions are included.
In addition, every year the city considers updates to the city’s CIP not only for improvements to the
storm drainage system but also the transportation system, water and sanitary sewer utilities, and park
facilities. Drainage system maintenance and condition assessments have identified a number of pond
maintenance and other projects such as dredging to restore or enhance the effectiveness of those
features, and priority actions have been included in the CIP.
City of Chanhassen 2040 Comprehensive Plan359
Page | 5-11
Road, utility, and park projects are also an opportunity to incorporate water quality and quantity BMPs.
These projects are intended to maximize the amount of nutrient and sediment removal from
stormwater prior to being discharged into the lakes, streams, and wetlands in the community. Concept-
level planning estimates the cost of potential BMPs for inclusion in the CIP. Specific BMP selection and
design are undertaken during project design.
The CIP also includes collaborative projects with the watershed districts. The city is open to working
together with the districts to identify additional projects or opportunities to integrate water resource
and conservation protection, including working with the Minnehaha Creek district in advancing its
Balanced Urban Ecology policy.
The city also intends to prepare a Natural Resource Management Plan to identify, prioritize, and
recommend restoration and management strategies for all public natural areas, and will consult with
the various WMOs to obtain their input and feedback.
This CIP is reviewed and updated annually, and additional projects may be added as more or better
information is available or as opportunities arise.
5.3 IMPLEMENTATION PLAN FUNDING
The city will fund the Implementation Program (IP) through a combination of sources. The primary
source of funds will be Stormwater Utility Fees. The types of activities included in the IP can be
categorized as operations and maintenance; programs and special studies; and capital projects.
Operations and maintenance and most of the proposed programs and special studies would be funded
by the Stormwater Utility, the General Fund, or the Water Surcharge Fund. For capital projects, other
sources of funding may be available to supplement Stormwater Utility Funds: matching funds from the
watershed districts, contributions from other agencies for cooperative projects, or grant funds.
City of Chanhassen 2040 Comprehensive Plan360
Page | 5-12
Table 5.2. Chanhassen LWMP Implementation Plan 2018-2027.
Program/Project Description Cost Year Funding Source*
PROGRAMS AND ADMINISTRATION
Administration
Maintain and update modeling tools Update the city’s integrated stormwater management models and tools and develop new tools and linkages as
necessary to manage stormwater and water quality.
$30,000 As needed SWUF, GF
Implement SWPPP Undertake operations and maintenance activities in accordance with the City’s approved SWPPP and NPDES permit
including Vegetation Management, BMP Inspection and Maintenance, and IDDE programs
$430,000 Annual SWUF
Implement ordinances Implement stormwater management, shoreland, floodplain, and wetland management ordinances. Implement permit
program to administer standards and ordinances
$95,000 Annual SWUF, permit fees
Revise and update ordinances Update ordinances as necessary, based on new MOU, WMO or NPDES permit requirements, evolving standards and
new best management practices.
$5,000 As needed SWUF
CIP Updates Update the CIP annually $5,000 Annual SWUF
WCA Administration Continue to act as LGU for administration of WCA for wetlands in the city. $40,000 Annual Permit fees
Education and Outreach
General education and outreach programming Both individually and with the city’s partners and using a variety of delivery mechanisms to cultivate an
environmentally literate public to promote an active community role in sustainable management of water resources.
$30,000 Annual SWUF, WMO, CWF
Education and Outreach Plan Complete the Education and Outreach Plan to assist with targeting educational needs, audience, funding priorities,
partnership opportunities and annual program assessment
$5,000 2020 SWUF
Monitoring
Water quality and AIS monitoring Continue CAMP and AIS support partnership monitoring programs. Develop additional citizen monitoring
opportunities that prioritize resident and water resource concerns or fill gaps in existing programs.
$20,000 Annual SWUF, WMO, CWF
TOTAL: Programs and Administration $660,000
CAPITAL IMPROVEMENT PROJECTS
Improvement Projects
Downtown Water Reuse Project Integrate reuse irrigation from Hwy 5 storm ponds into downtown vision and update project $350,000 2020 SWUF
Lake Susan Park Water Re-use Project
Partner with RPBCWD to install pump and treatment device to withdraw water from Lake Susan Pond to irrigate Lake
Susan Park.
$333,000 2018 WMO, CWF, SWUF
Chanhassen HS Water Re-use Project
Partner with RPBCWD to install pump and treatment device to withdraw water from a pond on the property to
irrigate ballfields and other green space at the high school.
$350,000 2018 WMO, CWF, SWUF
W Central Lotus Lake Channel Restoration Phase II Stabilization of 1,540 lineal feet of deeply incised channel draining 347 acres to Lotus Lake $275,000 2021 WMO, SWUF
Lower Bluff Creek TMDL Implementation
Volume reduction and rate control in the Bluff Creek drainage are to reduce channel and gully erosion and
sedimentation into the Creek. Includes LMRWD Bluff Creek Restoration Project and Erosion Repair Project
$1,450,000 2018-2022 WMO, SWUF
Upper Riley Creek Channel Stabilization
Stabilization of in- and near-stream bank undercutting, escarpment and gully erosion in Riley Creek adjacent to the
Public Works Facility.
$132,000 2021 WMO, SWUF
Rice Marsh Lake Iron Enhanced Sand Filter Installation of an iron-enhanced sand filter within Rice Marsh Lake Park. $300,000 2019 WMO, SWUF
Enhance and Restore Wetland Draining to Lake
Hazeltine
Enhance and restore wetlands draining to impaired lake $200,000 2025 WMO, CWF, DNR,
SWUF
Christmas Lake Stormwater Volume and Pollutant Load
Reduction
To be identified $200,000 2027 WMO, SWUF
Lake Virginia Stormwater Volume and Pollutant Load
Reduction including Lake St. Joe and Minnewashta
Feasibility study to identify areas of potential shoreline/streambamk stabilization and stormwater improvements in
2019. Final projects to be identified
$620,000 2019-2026 WMO, SWUF
Lake Ann Parking Lot/Boat Launch Improvements Swale and infiltration basing to capture stormwater runoff along parking lot and boat ramp entering Lake Ann $100,000 2025 WMO, SWUF, GF
101 Stormwater Improvements Including Chloride
Management
Stormwater and chloride management improvements as part of the 101 realignment project. $1,000,000 2020-2023 WMO, SWUF,
CWF, grants
Lotus Lake Outfall Improvements Repair and restore highly eroded outfall channels entering Lotus Lake. Includes Kerber Pond outfall. $500,000 2024 WMO, SWUF
Street Sweeper/equipment Opportunities to improve current street sweeping practices and equipment. The City currently has only one street
sweeper
$239,000 2019 SWUF, GF, WMO
Stormwater Infrastructure Maintenance/ Replacement Annual repair or replacement of public stormwater infrastructure costing less than $25,000. $450,000 Annual SWUF
Stormwater Pond Improvements Inspection, repair, and cleaning of stormwater ponds $760,000 Annual SWUF
Stormwater Management Component of Street Projects Infrastructure construction or expansion associated with street improvement projects $2,985,000 Annual SWUF, WMO, CWF
City of Chanhassen 2040 Comprehensive Plan361
Page | 5-13
Program/Project Description Cost Year Funding Source*
Lake Lucy Lane Culvert Replacement Culvert replacement and stormwater improvements between wetlands North and South side of Lake Lucy Ln $30,000 2018 SWUF
Pioneer Trail Flood Mitigation Reduce flood potential to residential structures by improving failing and deficient infrastructure $150,000 2019 SWUF
Strategic Property Acquisition Strategic property acquisition $800,000 Periodic SWUF, WMO
TOTAL: Capital Improvement Projects $11,204,000
•GF = General Fund; SWUF = Storm Water Utility Fund; WMO = local Watershed Management Organization; CWF = Clean Water Fund or similar grant funding
City of Chanhassen 2040 Comprehensive Plan362
Page | 5-14
Table 5.3. Chanhassen LWMP Implementation Plan 2018-2027 by year.
Program/Project 2018 2019* 2020* 2021* 2022* 2023* 2024* 2025* 2026* 2027*
Administration
Maintain and update modeling tools $30,000 $31,200 $32,448 $33,746 $35,096 $36,500 $37,960 $39,478 $41,057 $42,699
Implement SWPPP $430,000 $447,200 $465,000 $483,691 $503,000 $523,120 $544,045 $565,807 $588,439 $611,977
Implement ordinances $95,000 $98,800 $102,752 $106,862 $111,136 $115,581 $120,204 $125,012 $130,012 $135,212
Revise and update ordinances $5,000 $5,200 $5,408 $5,624 $5,850 $6,084 $6,327 $6,580 $6,843 $7,117
CIP Updates $5,000 $5,200 $5,408 $5,624 $5,850 $6,084 $6,327 $6,580 $6,843 $7,117
WCA Administration $40,000 $41,600 $43,264 $44,995 $46,794 $48,666 $50,613 $52,638 $54,744 $56,934
Education and Outreach
General education and outreach programming $30,000 $31,200 $32,448 $33,746 $35,096 $36,500 $37,960 $39,478 $41,057 $42,699
Education and Outreach Plan $5,000 $5,200 $5,408 $5,624 $5,850 $6,084 $6,327 $6,580 $6,843 $7,117
Monitoring
Water quality and AIS monitoring $20,000 $20,800 $21,632 $22,497 $23,397 $24,333 $25,306 $26,318 $27,371 $28,466
CAPITAL IMPROVEMENT PROJECTS
TMDL/Resource Improvements
Downtown Water Reuse Project $350,000
Lake Susan Park Water Re-use Project $50,000
Chanhassen HS Water Re-use Project $100,000
W Central Lotus Lake Channel Restoration Phase II $250,000
Lower Bluff Creek TMDL Implementation $250,000 $175,000
Upper Riley Creek Channel Stabilization $132,000 $25,000 $75,000
Rice Marsh Lk Iron Enhanced Sand Filter $300,000
Enhance and Restore Wetland Draining to Lake Hazeltine $200,000
Christmas Lake Stormwater Volume and Pollutant Load
Reduction
$200,000
Lake Virginia Stormwater Volume and Pollutant Load
Reduction including Lake St. Joe and Minnewashta
$20,000 $600,000
Lake Ann Parking Lot/Boat Launch Improvements $100,000
101 Stormwater Improvements Including Chloride
Management
$1,000,000
Lotus Lake Outfall Improvements $500,000
Maintenance/Protection Projects
Street Sweeper $239,000
Stormwater Infrastructure Maintenance/ Replacement $50,000 $50,000 $50,000 $50,000 $50,000 $75,000 $75,000 $100,000 $100,000 $100,000
Stormwater Pond Improvements $80,000 $80,000 $80,000 $80,000 $80,000 $100,000 $100,000 $300,000 $300,000 $300,000
Stormwater Management Component of Street Projects $360,000 $250,000 $100,000 $250,000 $250,000 $300,000 $300,000 $500,000 $500,000
Lake Lucy Lane Culvert Replacement $30,000
Pioneer Trail Flood Mitigation $150,000
Strategic Property Acquisition $300,000 $75,000 $75,000 $75,000 $75,000 $75,000 $75,000 $100,000 $100,000 $100,000
TOTAL,
IMPLEMENTATION PROGRAMS AND PROJECTS $1,891,000 $1,596,400 $1,518,768 $1,322,409 $1,602,069 $2,302,952 $1,885,069 $1,968,471 $2,503,209 $2,139,338
*Assumes an annual 4% budget increase; actual increase may differ.
City of Chanhassen 2040 Comprehensive Plan363
Page | 5-15
5.4 ADDRESSING IDENTIFIED PROBLEMS AND ISSUES
As noted earlier in Table 3.2 of this Plan, the planning process revealed a number of problems and
issues. Table 5.4 repeats those by category, and describes how each was addressed in this Plan.
Table 5.4. Implementation actions addressing identified problems and issues.
Category Identified Problems and Issues Identified Solutions
Water Quality
Conditions
Lakes and streams are listed on the Clean
Water Act Section 303(d) TMDL List of
Impaired Waters.
The CIP includes, and will periodically be
updated to include projects to achieve
pollutant load and runoff volume reductions to
address listed impairments and NPDES permit
requirements.
Nonpoint source pollution reduction is
necessary through maintenance practices
such as street sweeping, sump manhole
cleaning, and BMP inspections.
The city has an ongoing program of routine
and targeted street sweeping and sump
manhole cleaning. Public BMPs will continue
to be systematically inspected. Maintenance
activities and projects programmed into the
CIP.
Drainage and
Flooding
Near stream gullies and escarpments
should be addressed to control sediment
deposition into surface waters and to
protect property and infrastructure.
The city will continue to work with WMOs to
protect existing and improve flood storage
capacity through targeted BMPs and
increased street sweeping. The city will
prioritize BMPs that protect or repair highly
erodible and sensitive soil areas in the Bluff
Creek Overlay District.
Regulatory
Requirements
and Operational
Policies
Atlas 14 updated precipitation frequency
data is available for adoption.
The city will require stormwater modeling
work to use Atlas 14 precipitation depths and
nested distributions.
Approaches such as Minimal Impact
Development and Integrated Management
Practices are available to reduce the public
expenditures necessary to control runoff
and protect and improve water quality.
The city will continue to work with developers
to incorporate standards into new
development and redevelopment.
The City’s approved NPDES permit and
SWPPP requires ordinance revisions and
operating program enhancements.
City Code will be revised within 12 months to
incorporate volume management and water
quality requirements.
City goals, policies and ordinances to help
protect natural resources may need review
and refinement.
The city currently has ordinances in place
protecting steep slopes and bluffs, shorelands,
wetlands, and the Bluff Creek Overlay District
Water-Based
Recreation
Needs
Water quality should be protected and
improved to protect and enhance
recreational opportunities.
This Plan includes a number of capital projects
and maintenance programs intended to
improve water quality to better support
fishing, swimming and boating.
Control of aquatic invasive species (AIS)
continues to be an important concern
The city will continue to work with CCWMO,
watershed districts, lake associations, and DNR
to undertake AIS program activities such as
watercraft inspections, biocontrol, fish
restocking, or other similar activities.
Maintenance
Requirements
BMP maintenance and repair requirements
have been identified during NPDES
The city will continue to systematically assess
the condition of public BMPs. The CIP includes
City of Chanhassen 2040 Comprehensive Plan364
Page | 5-16
Category Identified Problems and Issues Identified Solutions
inspections, including restoration of
storage capacity, repair of erosion, and
prevention of future problems.
and will periodically be updated to include
projects identified in the pond inventory and
inspections.
Street sweeping, sump manhole cleaning,
and BMP inspections are necessary on an
ongoing basis to help reduce nonpoint
source pollutant loads.
The maintenance program includes provisions
for regular and special street sweeping;
inspection and maintenance of sump
manholes and catch basins; basin inspections
and repairs; illicit discharge detection; and
erosion control.
Education and
Outreach
Education and outreach efforts could be
expanded with a focus on targeted groups
with new and expanded educational
opportunities.
Opportunities exist with CCWMO and other
organizations to improve efficiency and
reduce duplication of efforts.
Education and outreach efforts will be
continued including written and electronic
communications, and opportunities for
participation by citizen volunteers such as the
Wetland Health Evaluation Program (WHEP)
and the Citizen Assisted Monitoring Program
(CAMP) for lakes.
Increase collaboration and coordination with
CCWMO and other organizations.
Financial
Resources
Financial resources are limited, requiring
that projects be prioritized.
The budget in this Plan prioritizes operating
programs and projects to address both
regulatory and operational needs and water
resource improvements. The city will continue
to leverage available funding by collaborating
with partners and seeking grant funding.
Groundwater
Protection
The LWMP should be coordinated with the
Wellhead Protection Program and Carver
County Groundwater Plan (2016) so that
policies that encourage infiltration and
groundwater recharge are consistent with
the policies to protect sensitive
groundwater recharge areas.
Infiltration requirements are integrated with
Wellhead Protection requirements and Carver
County Groundwater Plan (2016) to protect
groundwater quality.
Seminary Fen is a rare calcareous fen and
Assumption Creek is a trout stream, both
of which are dependent on groundwater.
The city participates in the Met Council’s
Seminary Fen Work Group to study the effects
of groundwater pumping on Seminary Fen.
City ordinance imposes stringent standards on
development and redevelopment in the
Assumption Creek drainage area.
Collaboration
Opportunities
There are opportunities for collaboration
with other agencies such as the watershed
districts, the Three Rivers Regional Park
District, and state agencies to leverage
expertise and resources to finance and
construct improvements.
The city will continue to collaborate with the
watershed districts to identify and complete
capital projects and pursue opportunities with
development and redevelopment projects.
City of Chanhassen 2040 Comprehensive Plan365
Page | 6-1
6.0 Amendments to the Plan
The Chanhassen Local Water Management Plan extends from 2018 to 2027. However, this document is
intended to be a planning tool that will change as the city’s needs change and may be amended as
necessary to meet the city’s goals. The Implementation Plan will be reviewed and updated annually.
6.1.1 WMO Plan Amendments
Revisions to this Plan required by Watershed Management Organization (WMO) Plan Amendments will
be addressed in accordance with Minn. Stat. 103B.235 and Minn. Rules 8410.0160 Subp.6.
6.1.2 Major Plan Amendments
Major Plan Amendments to this Plan, such as adoption of significant revisions to official controls or
actions that would change the Goals of the Plan will be reviewed by the City Council and submitted to
the appropriate WMO for comment and approval and to the Metropolitan Council for comment as set
forth in Minn. Stat. 103B.235 and Minn. Rules 8410.160 Subp. 6.
6.1.3 Routine Updates
The Implementation Plan will be reviewed and updated as needed as the city’s annual NPDES, operating
programs, and CIP and project needs are evaluated and completed. The city may make routine updates
including budget and CIP changes, changes in education and outreach programming, revisions in
operations and maintenance practices and other programming changes that are consistent with the
Goals and policies set forth in this Plan without making formal revisions to this document.
City of Chanhassen 2040 Comprehensive Plan366
Page | 7-1
7.0 References
Barr, 2010. Bluff Creek TMDL Biological Stressor Identification.
<http://www.pca.state.mn.us/index.php/view-document.html?gid=13751>
Barr, 2013a. Bluff Creek Watershed Total Maximum Daily Load Report: Turbidity and Fish Bioassessment
Impairments. <http://www.pca.state.mn.us/index.php/view-document.html?gid=19684>
Barr, 2013b. Lake Lucy and Lake Ann Use Attainability Analysis Update.
<http://www.rpbcwd.org/files/7213/8426/4821/LakeLucy_LakeAnn_UAAUpdate_September2013_FINA
L.pdf>
Bonestroo, 1996. Bluff Creek Watershed Natural Resources Management Plan.
<http://www.ci.chanhassen.mn.us/DocumentCenter/Home/View/323>
MPCA, 2001. Minnesota River Basin Plan. <http://www.pca.state.mn.us/index.php/view-
document.html?gid=9946>
Wenck, 2013. Lake Susan Use Attainability Assessment (UAA) Update.
<http://www.rpbcwd.org/files/4013/8426/4706/Lake_Susan_Report_FINALred1.pdf>
City of Chanhassen 2040 Comprehensive Plan367
[This page intentionally blank for printing]
City of Chanhassen 2040 Comprehensive Plan368