1a Seminary Fen SetbacksCITYOF
CHANHASSEN
690 City Center Drive
?0 Box 147
Chanhassen, Minnesota 55317
Phone
952. 937.1900
General Fax
952.937.5739
Engineering Deparonent Fax
952.937.9152
Building Department Fax'
952.934.2524
Web Site
www. ci. &anhassen. mn. us
MEMORANDUM
To: Todd Gerhardt, City Manager
From: Lori Haak, Water Resources Coordinator
Date: August 14, 2001
Re: Calcareous Fen Setback
PURPOSE
Following a visit to the Assumption Seminary site and conversations with
representatives from several governmental agencies on June 4, 2001,
Commissioners Sacchet and Kind requested that staff explore an increased
setback for the Seminary Fen to protect it from potential damage (water quality
decrease, loss of ecosystem, loss of rare plants) and to prevent exotic species from
invading and out-competing native plant species. This memo outlines staff
recommendation regarding an increased setback from calcareous fens.
BACKGROUND
The Seminary Fen is located in the southern portion of Chanhassen, west of Bluff
Creek Drive and south of the Hennepin County Regional Trail Corridor. The 90
acres of calcareous seepage fens are within a 500-acre wetland complex that also
contains wet meadows, emergent marshes, and shrub swamps.
The City of Chanhassen has significant precedent in determining the Seminary Fen
to be important to the community and worthy of protection. The Seminary Fen has
been identified in the Surface Water Management Plan (Attachment 1), the Bluff
Creek Watershed Natural Resources Management Plan (Attachment 2), and the City
of Chanhassen's Comprehensive Plan (Attachment 3) as the highest priority for
conservation. The Surface Water Management Plan states that the fen should be
protected from developmental impacts in the adjacent uplands and in-flowing water
by use of upland buffer zones and setbacks. The Bluff Creek Watershed Natural
Resources Management Plan states that "the Seminary Fen should receive the
highest level of protection to avoid declines in wetland quality... [as it] is an
The CiO, of Chanhassen. A growh~g community with clean lakes, ttuality schools, a cha~min~ downtown, thrivine businesses, and beautiful parks. A ~reat place to live, work, and /~la~.
Calcareous Fen Setback
August 14, 2001
Page 2
extremely rare type of wetland found in the state." It also reflects a desire to see the areas
preserved as a natural area, or protected with conservation easements. In the Comprehensive Plan,
it is said, "preserving and protecting this resource should be at the top of the city's wetland
protection and preservation policies."
The Seminary Fen is a high regional priority for the Department of Natural Resources (DNR),
and it is protected by the Wetland Conservation Act (Attachment 4). Because calcareous fens are
so rare, they have special status in the state wetland law.
The current wetland setback for a pristine wetland in the City of Chanhassen is 100 feet, with a
buffer strip of 20-100 feet, and a minimum average width of 50 feet (see Attachment 5). The
Seminary Fen complex is currently classified as "pristine" because of the high quality of the
ecosystem and the presence of rare plants. It is the only pristine wetland complex remaining
within Chanhassen.
RATIONALE
The Seminary Fen is of great value to the City of Chanhassen for several reasons:
Fens have a variety of functions necessary to the survival of diverse ecosystems in the
surrounding area. They control floods, filter pollutants from water, sustain biodiversity,
provide plant and animal habitats, contribute to the water flow, and store carbon in their
peaty soils, which aids in the healthy development of plants.
2~
The Seminary Fen is one of Minnesota's rarest plant communities and is home to eight rare
plants including three "special concern" species (Twig rush, Marsh arrow-grass and Small
white lady's slipper) and five "threatened" species (Sterile sedge, Beaked spike rush, Hair-
like beak rush, Whorled nut rush and Valerian).
3~
The Seminary Fen is a calcareous fen. Calcareous fens are created when cold ground water
picks up dissolved calcium and magnesium as it flows through hillsides rich in these
minerals. These fens are extremely rare. They create a unique set of ecological conditions:
there are specific types of plants that exist in, and prefer, the cold and alkaline water. Twenty
percent of approximately five hundred calcareous fens in the world are in Minnesota. The
Seminary Fen makes up five percent of the area of all the fens in Minnesota.
.
The Seminary Fen is relatively untouched: it is in its pre-settlement condition. However,
exotic species such as leafy spurge and buckthorn are currently hovering on the edge, ready
to invade the fen. Thus, a management plan is needed in the near future to preserve the
existing ecosystem. The City of Chanhassen has joined with other governmental and non-
governmental organizations to apply for a DNR Greenways Planning Grant. The grant would
help fund the development of a Stewardship and Protection Plan for the Assumption
Seminary area. Working with the Lower Minnesota River Watershed District (LMRWD),
Calcareous Fen Setback
August 14, 2001
Page 3
the City would provide the residents of the area with: information about the uniqueness of
Assumption Creek, the Seminary Fen, and the surrounding area; several means by which
residents can protect their properties; and an opportunity to be involved in the development
of the stewardship and protection plan.
o
Assumption Creek contains a naturally reproducing trout population. Creeks like
Assumption Creek are extremely rare natural formations. Assumption Creek is codependent
with the calcareous fen for minerals and groundwater and would thus be negatively impacted
if the fen were to decrease in size or quality. Assumption Creek is one of 15 streams in the
Metro area with a naturally reproducing trout population, and the only one in the West Metro
with a native brook trout population.
OTHER CALCAREOUS FENS
The two calcareous fens in closest proximity to the Assumption Seminary property are the
Savage Fen in Savage and the Nelson Fen near Stewartville.
Savage
The Savage Fen is a 425-acre wetland complex owned by the U.S. Fish and Wildlife Service
(USFWS) and private owners. It sits amid highways, housing developments, and industrial
buildings in Scott County. The calcareous fen is in the heart of the wetland complex and
comprises 64 acres. In 1997, there was question as to whether Scott County officials could build
a four-lane highway through the center of the complex, and they requested a bridge be allowed to
span the fen. However, the Minnesota Environmental Partnership said that bridge construction
would alter the fen's hydrology, and road salt could destroy rare plants. These changes could
have threatened the wetland's survival and allowed exotic species to invade. Because of the
potential dangers to the ecology of the fen, the proposal of the bridge and highway construction
was defeated. A traffic analysis study was completed in 1999 to determine a route for a new
highway in the vicinity of the fen, but it indicated that a road through the fen would not ease
congestion in the Savage area. Possible road construction is not the only danger to the Savage
Fen. Increased groundwater withdrawal for public water supply in this sensitive area has
lowered the water table and adversely affected the calcareous fen. Savage does not currently
have a fen setback in place.
Stewartville
The Nelson Fen is a very small calcareous fen located within a Wildlife Management Area
(WMA) in Olmsted County. The fen itself occupies less than one acre within the 80 acre WMA,
and a shrub meadow wetland surrounds the fen. There are three state threatened species that live
within the Nelson Fen: sterile sedge, valerian, and beaked spike rush. The active management
of this WMA consists mainly of prescribed burning.
PERTINENT ITEMS
Calcareous Fen Setback
August 14, 2001
Page 4
Staff has identified the following items that should be taken into consideration as the City
contemplates the adoption of a fen setback:
There is no precedent in this area. The protective buffers around both calcareous fens are
on state-owned land.
2. Though the setback will be more restrictive and thus serve to protect the fen, it will still
allow development near the fen, and it acknowledges that development may. take place if
the land remains in private ownership.
3. The land on which the fen is located is zoned primarily A-2 (Agricultural Estate). The
minimum lot size for A-2 is 2 ½ acres and a 1-unit per 1 O-acres density must be
maintained. A portion of the land is zoned RR (Rural Residential). The minimum lot
size for RR is 2 ½ acres and a 1-unit per 1 O-acres density must be maintained. Staff
anticipates that, in most cases, the large lots will be able to accommodate a structure that
meets the required setbacks. (Staff will provide more details at the Planning Commission
meeting.)
4. The City has been encouraged by the DNR, Friends of the Minnesota Valley, the U.S.
Fish and Wildlife Service, the LMRWD, and the Minnesota Land Trust to create a fen
setback.
5. Anything that affects the complex hydrological balance of precipitation, surface water
flow, and groundwater discharge that provides water for the fen can lead to its
degradation.
6. Hydrologic information has not been compiled for the fen because a comprehensive
hydrologic study could be destructive to the fen and there would be a negative net gain.
Staff is unsure as to the extent of the wetland and fen recharge area; however, increasing
the setback would certainly enlarge the amount of recharge area under City protection.
7. According to the Center for Watershed Protection (CWP), increases in the amount of
impervious surface (such as pavement) near creeks or wetland areas can have negative
impacts on the adjacent water bodies. Citing many independent lines of research, the
CWP states that it is extremely difficult to maintain predevelopment quality when
watershed development exceeds 10 to 15% impervious cover. Staff has estimated the
amount of impervious surface in the watershed to be 5% at present.
8. A setback of 100 feet is necessary for good quality maintenance and protection, according
to an Iowa State impact study. To achieve the optimal level of protection, a buffer is also
required.
9. A setback with a buffer requirement would prevent the intrusion of non-native plant
species to some extent and would help to preserve rare plant species, habitat diversity,
and the overall integrity of the ecosystem.
10. According to a study conducted by the Minnesota Storm Water Advisory Group in 1997,
wetland buffers should be 25 feet for minimum benefits, and 150 feet or more for the
protection of sensitive species. Standards should be increased for higher functions, such
as trout streams. The best-suited riparian buffers are more complex combinations of
herbaceous and woody native species suited to the area.
Calcareous Fen Setback
August 14, 2001
Page 5
11. In a study done in 1992, the Shorelands and Coastal Zone Management Program of the
Washington Department of Ecology found that to prevent significant water quality
impacts, the buffer needs to be 100 feet or greater. Furthermore, buffers need to retain
plant structure for a minimum of 200 to 300 feet beyond the wetland to retain wetland-
dependent wildlife.
PLANNING COMMISSION UPDATE
At the Planning Commission meeting on July 17, 2001, Commissioner Sacchet requested
that staff explore the feasibility of an increased setback, per the Washington Department of
Ecology study in 1992 (Pertinent Item #11). Staff has investigated this option and
recommends a setback of 150 feet for several reasons:
1. Acquisition is the preferred solution. Acquisition is the only way to ensure riparian
areas are managed properly. Management of the setback and buffer is necessary to
maintain hydrology, vegetation and wildlife habitat. Management tools may
include, but are not limited to, the removal of invasive species, controlled burning
and monitoring programs. Additionally, development of the site may be disastrous
for the fen since any storm water ponds created on the site may interrupt ground
water flows. If acquisition is not possible and the property was subdivided, the City
could obtain management rights of the fen property via outlots. However, if the lots
do not go through the subdivision process, management rights could not be
guaranteed.
2. DNR Precedent: The DNR-required setback for Natural Environment lakes is 150
feet. It is logical to expect that the setbacks for calcareous fens would be at least as
stringent as those required for Natural Environment lakes.
3. Setbacks Combined with Buffers: In the past, the City has opted to decrease
setback distances when setbacks are used in combination with buffers of natural
vegetation. The proposed ordinance would require the entire 150-foot setback to be
maintained or established in a prairie buffer.
4. Ambiguous Findings: The findings located by staff regarding setbacks and/or
buffers appear to be ambiguous. While a 1992 study done by the Washington
Department of Ecology found that a buffer of over 100 feet is necessary to prevent
significant water quality impacts, an Iowa State University impact study stated that
a setback of 100 feet is necessary for good quality maintenance and protection. The
Washington study stated that buffers should be 200-300 feet wide to provide habitat
for wildlife, while the Iowa study indicated simply that a buffer is required for
adequate protection. Both studies appear to agree that, in general, buffers and
setbacks will assist in resource protection.
5. Legal Issues: The City of Chanhassen could become involved in a takings issue if
the setbacks become larger than 150 feet, as large portions of the lots surrounding
the creek would become unbuildable.
Calcareous Fen Setback
August 14, 2001
Page 6
RECOMMENDATIONS
Staff recommends that the Planning Commission recommend the City Council approve the
following motions:
"Section 20-403 shall be modified to read:
(c) Wetland types. This article establishes three (3) four (4) wetland types and'one body type.
Wetlands, ag/urban. Wetlands that have been influenced by agricultural or urban
(residential, commercial, or industrial) land usage are called ag/urban. Influences include:
over nutrification, soil erosion and sedimentation, and water quality degradation. As a result
of these influences there is a loss of plant species diversity, over-crowding and domination by
invasive species such as reed canary grass, and reduction in wildlife habitat.
(2)
Wetlands, natural. Natural wetlands are still in their natural state and typically show little
sign of impact from surrounding land usage. The vegetative communities of these wetlands
are characterized by a diversity of plant species with mixed dominance of species. Other key
factors include: presence of natural indicator species, good wildlife habitat, and being
aesthetically pleasing.
(3)
Wetlands, pristine. Wetlands that exist in a natural state and have special and unusual
qualities worth protecting at a high level are called pristine. These qualities include:
outstanding vegetation community, native species population, rare or unusual species present,
and habitat for rare wildlife species.
(4)
Utilized. Utilized water bodies created for the specific purpose of surface water runoff
retention and/or water quality improvements. These water bodies are not to be classified as
wetlands even if they take on wetland characteristics. Wetland alteration permits shall not be
required to undertake work on these water bodies.
Calcareous Fen. A calcareous fen is a peat-accumulating wetland dominated by
distinct groundwater inflows having specific chemical characteristics. The water is
characterized as circumneutral to alkaline, with high concentrations of calcium and low
dissolved oxygen content. The chemistry provides an environment for specific and
often rare hydrophytic plants.
and
"Section 20-406 shall be modified to read:
(c) For lots of record containing or abutting a calcareous fen, the following minimum
provisions are applicable:
(1) Structures shall maintain a minimum setback of 150 feet; and
Calcareous Fen Setback
August 14, 2001
Page 7
(2) Prairie buffer shall be established and/or maintained within the entire 150-foot
setback."
ATTACHMENTS
1. Excerpt from Surface Water Management Plan, 1994.
2. Excerpt from Bluff Creek Watershed Natural Resources Management P1an, 1996.
3. Excerpt from City of Chanhassen Comprehensive Plan, 1998.
4. Minnesota Wetland Conservation Act re. Calcareous Fens (MR 8420.1010)
5. Wetland Setbacks, Chanhassen City Code, Sections 20-403 and 20-406.
6. Proposed Ordinance
G:XENG\LoriWlemosWen Memo 2.doc
Proposed improvements at Ponds LOM-P1.3, LOM-P1.4, LOM-P1.8, and LOM-PI.12
described in Section IV-J3. and Appendix C are high priority, highly efficient
improvements which contribute the most to enhance the water quality of the pristine
wetlands. :
Wetlands
Wetlands A34-8(1) and A34-12(1) should be protected from impacts of development
of adjacent uplands and from in-flowing water by use of upland buffer zones and
minimum setbacks as detailed in the Ordinance.
Wetlands A34-8(1) and A34-12(1) should be improved by allowing more water to pass
through the railroad grade in the northern portion of A34-12(1).
Wetlands such as A27-16(1) and A27-16(2) should be protected by implementing the
upland buffer zones and minimum setbacks as detailed in the Ordinance.
.
Purple loosestrife population center at wetland A34-8(1) should be treated in
accordance with State guidelines.
IV-K Drainage to Neighboring Communities
IV-ICI Drainage to Christmas Lake
Watershed Description: The portion of Chanhassen draining to Christmas Lake is located at
the north central boundary of the City with a total area of about 234 acres. This area does not
receive any runoff from other watersheds inside or outside the City.
Topography within the area is fairly steep with a lot of small depressions, wetlands and ponds.
Land surface elevations range from about 1,040 feet to 930 at Christmas Lake shoreland. The
Christmas Lake area is fairly well developed (about 75%).
F2. Ciree~w~y
F~, Oevelop~ent
considering the highly developed nature of the watershed that
surrounds it.
The design of the b'ails and park system should continue to move forward
as the Park and Recreation Commission recommends and under the
viewpoints discussed above.
Development of the land and transportation routes should continue to
move forward with Watershed-Based Zoning and Cluster Development
and protection of the primary and secondary zones as discussed in section
V.E. The East Gorge area is erosive and it is important that the City require
setback regulations beyond the existing bluff ordinance to protect the
spring-fed creek. This may require an amendment to the existing bluff
ordinance.
Much of the area appears to already be divided into large lot residential
home sites. Future development would target further subdivision of
parcels. The City's efforts to manage this area should focus on cooperative
agreements to protect the area, especially the southern areas Where
higher quality exists.
IV. G Regio~ 5- 5emi~ Fe~
6.1 N~tural Resource~
· Approach
The Seminary Fen should receive the highest level of protection
to avoid declines in wetland quality. This wetland should remain
connected to the lower gorge area of Bluff Creek. Naturally
reproducing trout within the creek on this property should also
be protected.
The Seminary Fen is an extremely rare type of wetland found in
the state and should be protected from encroachment due to
draining, filling and exotic species (see Figure 14). '1o retain
groundwater discharge into this area, development should .be
restricted on the bluff top areas so that recharge of groundwater
may oc4ur. Buffer strips should be a minimum of 100 feet on all
sides of this wetland. Disturbances, such as vegetation removal,
should not be allowed. This wetland should remain connected to
the lower gorge area of Bluff Creek. Naturally reproducing trout
within the creek on this property should be protected as well.
Z3luff Cree~ wa¢er~fied Nat~ral Resources Management Pla~
' 6.3 Deve!~pme~t
The design of the trails and park system should continue to move forward
as the Park and Recreation Commission recommends and under the
viewpoints discussed above.
Development of the land and transportation routes should continue to
move forward with Watershed-Based Zoning. and cluster development
and protection of the primary and secondary zones as discussed in section
V.E. The City should consider a variety of land uses in this area and should
choose the use that is most protective to the area. if possible, a means for
limited access for education purposes would be ideal. Maintenance of the
fen and trout stream is also important. Therefore. it is practical that lands
that are for sale be acquired and preserved as a natural area. Lands that are
not for sale should be protected with conservation easements.
W.H Ed~cc~tio~
The goals for the educational component of the plan were established '
after the following portion of the Steering Committee Vision:
... ~_ creek serves as a field laboratory for t[,e schools, teachers
and community in order to develop a stewardship of the land .... "
The implications of the vision require the development of a watershed
awareness program for the entire community (school, otizens, etc.) so that
the plan implementatio~ process is part of an ongoing community
education and involvement effort. There are some constraints, i.e., the
need for teacher training time, curricu!un~ develop~ent, field trips, and
suppo~'t fi'om the school prinopals.
The awareness program will focus on actively engaging children, faro,has.
and the general public in learning about P_,luff C~ eek, its ecological and
cultural characteristics and role. It will also consider ways fo~' the pubhc
and special groups (nature societies, schools, corporate voiunteers, ga,'den
clubs, etc.) to participate in cor,'idor research, restoration, monitoring and
demonstration p~'ojects.
The program will emphasize the need for co~ ~munity support beyo,~d
private needs to .public support and involvement and the collabol'ation with
other educational, community and business entities.
The City has initiated effo[ts to acquire a I O0-acre parcel to develop an
interpretive nature center in the upper reaches of the watershed bet~veen
the Minnesota ,~'boretum and the school site, south of Highway 5 and
COMPREHENSIVE PLAN
With the increase in Chanhassen's population in
recent years, the boat traffic on city lakes has also
increased.
As property taxes on lakeshore lots continually
increase, the demand for services to manage the,.,/_
problems arising on city lakes will also increase.
Future lake management within Chanhassen will be
finding the balance of protecting and improving
water quality, preventing overuse and abuse of the
resources, while maintaining accessibility for all
Chanhassen residents.
1/~ETLANDS
In 1992, the state of Minnesota passed the Wetland
Conservation Act (WCA), which put wetland
protection and preservation into law. The goal of
this act is to replace wetlands lost to previous
activities and to prevent the loss of existing
wetlands. Wetland identification and protection
have become integral parts of all development
~roughout the entire state, including Chanhassen.
The City of Chanhassen, who has had wetland '
protection ordinances in place since 1980, has
continued to take the lead on the issue of wetlands
and their protection. The city's 1994 Surface Water
Management Plan (SWMP) included identification
and reclassification of wetlands within the city. Low
areas were identified as possible wetland sites.
Wetland specialists made field identification of
these sites and detailed data sheets documenting
vegetation, landscape and existing conditions were
compiled. These data sheets serve only as a guide
for the city and are not to be used as the defining
wetland boundaries. Wetland boundaries are to be
determined by professional delineations conducted
by parties who propose to impact or develop land in
and around these areas. In addition, any proposed
development will be required to delineate their sites
for the existence of wetlands. From this study, a
wetlands map was generated and a new wetland
classification system was implemented, replacing
the state's classification system. The city went to
four levels of wetland identification; Pristine,
Natural, Ag/Urban and Utility. Pristine wetlands
were identified as wetlands that remain in their
r~atural state and have special and unusual
qualities worth protecting. Natural wetlands are
wetlands that still exist in their natural state and
typically show little sign of impact from surrounding
land use. Ag/urban wetlands have been impacted
1998
by either agricultural or urbanization activities.
Utility wetlands are water bodies specifically created
to manage surface water created by development.
The Seminary Fen located north of Hwy. 212, in the
southwest corner of the city, is the only wetland
classified pristine. In 1995, the Seminary Fen was
identified by the Minnesota Biological Survey as the
most important site in all of Hennepin, Carver and
Scott Counties. There are approximately 90 acres
of calcareous seepage fen in this area with rare
and threatened plant species. Preserving and
protecting this resource should be at the top of the
city's wetland protection and preservation policies.
With the change in wetland laws, the regulation of
wetlands has also. changed. The State of
Minnesota appointed the Minnesota Board of Water
and Soil Resources (BWSR) to oversee the
regulation of the WCA. BWSR, in return, appointed
Local Governing Units (LGUs) to implement the
WCA for wetland activities. Chanhassen was
appointed, as LGU for activities in its own City. This
change gave Chanhassen Some responsibility and
control over wetland activities, but permits and
approval were still required from the Army Corps of
,Engineers, the Minnesota Department of Natural
'Resources, Minnesota Pollution Control Agency
and local watershed districts, in an attempt to
simplify regulation, Chanhassen was one of a
select few LGUs selected to participate in a
program which would make LGUs the sole
governing agency in cases where wetland impacts
are less than three acres, in addition, 1996
revisions to the WCA allowed LGUs to develop their
own comprehensive wetland plans. The City of
Chanhassen has submitted a draft plan to BWSR,
and because of previous work done in the SWMP,
the city is in the final stages of having their plan
approved. This plan allows the city to develop their
own rules specific to wetlands in Chanhassen.
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§ 20-402
CHANHASSEN CITY CODE
(6) Restricting and controlling the harmful effects of land development on wetlands.
(7) Allowing only development that is planned to be compatible with wetland protection
and enhancement.
(8) Providing stand~rds for the alteration of wetlands when alteration in allowed.
(9) Mitigating the impact of development adjacent to wetlands.
(10) Educating and informing the public about the numerous benefits and features of
wetlands and the impacts of urbanization.
(11) Obtaining protective easements over or acquiring fee title to wetlands as appropriate.
(Ord. No. 180, § 1, 12-14-92)
Sec. 20-403. Delineation of wetlands.
(a) Generally. Wetlands shall be subject to the requirements established herein, as well as
restrictions and requirements established by other applicable city ordinances and regulations.
The Wetland Protection Regulations shall not be construed to allow anything otherwise pro-
kibited in the zoning district where the wetland area is located.
(b) £ouncfarfes; maps. A wetland is land that meets the definition of "wetlands" set forth
in this article. Wetland boundaries and wetland types, as established by officially adopted city
maps, shall be prima facie evidence of the location and type of wetland. The official maps shall
be developed and maintained by the planning department. If an applicant questions whether
a wetland exists or disputes its delineation, the applicant shall have the burden to supply
detailed information for reviews supporting the applicant's position. The applicant shall pro-
vide appropriate technical information, including, but not limited to, topographical survey and
soil data deemed necessary for the city to determine the exact wetland boundary. The planning
director shall make a detern~ination to maintain the officially designated wetland boundary or
if th~ boundaries need to be corrected on city plans and maps based upon the data that is
supplied. Data for wetland determination shall be certified by a registered engineer, surveyor,
or a qualified wetland consultant. The applicant may appeal the planning director's determi-
nation of the wetland boundary and type to the city council.
(c) We~iancl types. This article establishes three (3) wetland types and one body type:
.(1) Wefl~n~ts, ~g/~rbsr:. Wetlands that have been influenced by agricultural or urban
(residential, commercial, or industrial) land usage are called ag/urban. Influences
include: over nutrification, soil erosion and sedimentation, and water quality degra-
dation. As a result of these influences there is a loss of plant species diversity, over-
crowding and domination by invasive species such as reed canary grass, and reduction
in wildlife habitat.
(2) Wet,ands, aat~ral. Naturs/wetlands are still in their natural state and typically
show little sign of impact from surrounding land usage. The vegetative community of
these wetlands are characterized by a diversity of plant species with mixed dominance
of species. Other key factors include: presence of natural indicator species, good wild-
life habitat, and being aesthetically pleasing.
Supp. No. 7 1 1 RR 9,
ZONING § 20-406
(3) Wetlands, pristine. Wetlands that exist in a natural state and have special and
unusual qualifies worth protecting at a Mgh level are called pristine. These qualities
include: outstanding vegetation' community, native species population, rare or un-
usual species present, and habitat for rare wild!i_fe species.
' {4) Utilized. Uti~llzed water bodies created for the specific purpose of surface water runoff
retention and/or water quality improvements. These water bodies are not to be
classified as wetlands even ffthey take on wetland characteristics. Wetland alteration
permits shall not be required to undertake work on these water bodies.
(Ord. No. 180, § 1, 12-14-92)
Sec. 20-404. No net loss.
To achieve no net loss of wetland, except as provided under section 20-416 of this article,
or authorized by a wetland alteration permit issued by the city, a person may not drain, grade,
/i11, burn, remove healthy native vegetation, or otherwise alter or destroy a wetland of any size
or type. Any alteration to a wetland, permitted by a wetland alteration permit must be fully
mitigated so that there is no net loss of wetlands.
(Ord. No. 180, § 1, 12-14-92; Ord. No. 202, § 2, 4-25-94)
Sec. 20-405. Standards.
The following standards apply to all lands within and abutting a wetland:
(1) Septic and soil absorption system must be a setback minimum of seventy-five (75) feet
from the ordinary high water mark of the wetland.
(2) The lowest ground floor elevation is two (2) feet above ordinary high water mark of the
wetland.
-
(3) Docks or walkways shall be elevated six (6) to eight (8) inches above the ordinary high
water mark or six (6) to eight (8) inches above the ground level, whichever is greater.
(4) Access across a wetland shall be by means of a boardwalk and only upon approval of
a wetland alteration permit.
(5) The city's Best Management Practices Handbook shall be followed.
(Ord. No. 180, § 1, 12-14-92; Ord. No. 202, § 3, 4-25-94; Ord. No. 240, § 11, 7-24-95)
.3~ Sec. 20-406. Wetland buffer strips and setbacks.
(a) For lots created after December, 14, 1992, (date of ordinance adoption), a buffer sfrip
shall be maintained abutting all wetlands. All existing vegetation adjacent to a wetland shall
be left undisturbed and applied toward the buffer strip unless otherwise approved by city
council. Buffer strip vegetation shall be established and maintained in accordance to the
following requirements. If the buffer area is disturbed, plant species shall be selected from
wetland and upland plants to provide habitat for various species of wildlife. Buffer strips shall
be identified by permanent monumentation acceptable to the city. In residential subdivisions,
a monument is required for each lot. In other situations,A monument is required for each three
No. 8 1188.3
20-406
CHANHASSEN CITY CODE
hundred (300) feet of Wetland edge. The buffer strips and structure setbacks shall meet the
fo]lowing standards:
.
'WeJZand Type Pristine
Principal Struc- 100'
ture Setback
Buffer Strip 20--100'
Natural Ag~ Urban Utilized
40' measured 40' measured 0'
from the out- from the out-
side edge of the side edge of the
buffer strip buffer strip
10~30' 0--20' O'
Buffer Strip
Minimum Aver-
age Width
50' 20' 10' 0'
% of Native
'v'egetmtion in
Buffer Strip
,,--.----
Entire Entire Optional Optional
AG/URB N WETLAND. ILLUSTRATION
I .
<' ' :~!'"'-) {
I /
_ . %
BL,FFER STRIP
10' I:;~P'TH)
The dimensions of the buffer strips may be adjusted by the city based upon the quality of the
wetland, local topographic conditions, and the type and design of development being proposed.
The table above provides minimum and maximum dimensions for the buffer strip. The use of
a meandering buffer strip to maintain a natural appearance is encouraged. Where roadways
are constricted next to a wetland, the average buffer strip width for the adjacent wetland shall
Supp ~0. 8 ~noo ·
ZONING § 20~107
be maintained. Structure setbacks are also described in the table. On single-family subdivi-
sions in the RSF district, the applicant must demonstrate that each lot provides sufficient area
to accommodate the applicable front yard setback, sixty-foot by forty-foot deep building pad,
and a thirty-foot rear yard area. All of these elements must be provided outside of designated
wetland and buffer strip areas.
Co) l%r lots of record on December 14, 1992 (date of ordinance adoption) within wetland
areas and for lands abutting a wetland area, the following minimum provisions are applicable
unless alternative plans are approved by the city under a wetland alteration permit:
Pri~stine Natural Ag / Urban Utilized
Setback Priuci- 100' 75' 75' 0'
pal Structure
The city may approve reduced wetland setbacks as outlined in subparagraph (a) above.
(Ord. No. 180, § 1, 12-14-92; Ord. No. 240, § 12, 7-24-95)
Sec. 20-407. Wetland alteration.
(a) An applicant for a wetland alteration permit shall adhere to the following principles in
descending order of priority:
(1) Avoiding the direct or indirect impact of the activity that may destroy or diminish the
wetland;
(2) Minimizing the impact by limiting the degree or magnitude of the wetland activity and
its implementation;
(3) Rectifying the impact by repairing, rehabilitating, or restoring the affected wetland
activity and its implementation;
(4) Reducing or eliminating the impact over time by preservation and maintenance
operations during the life of the activity; and
(5) Replacing unavoidable impacts to the wetlands by restoring or creating substitute
wetland areas having equal or greater public value as set forth in Minnesota Rules
8420.0530 to 8420.0630.
Co) A wetland alteration permit shall not be issued unless the proposed development
complies within the provisions of the Mitigation Section of this article, as well as the
s~nndards, intent, and purpose of this article.
(c) The treatment of wetlands to control nuisance algae.
(1) The city must be notified prior to the use of any form of treatment.
(2) At the time of notification, a person or company will be required to supply the following
information:
a. Location of pond.
b. Area of pond to be treated.
1188.5
CITY OF CHANHASSEN
CARVER AND HENNEPIN COUNTIES, MINNESOTA
ORDINANCE NO.
AN ORDINANCE AMENDING CHAPTER 20 OF THE
CHANHASSEN CITY CODE, THE ZONING ORDINANCE
The City Council of the City of Chanhassen ordains:
Section 1. Section 20403 (c) Delineation of wetlands shall be modified to read as follows:
(c) Wetland types. This article establishes three (3) four (4) wetland types and one body type.
Wetlands, ag/urban. Wetlands that have been influenced by agricultural or urban
(residential, commercial, or industrial) land usage are called ag/urban. Influences include:
over nutrification, soil erosion and sedimentation, and water quality degradation. As a result
of these influences there is a loss of plant species diversity, over-crowding and domination by
invasive species such as reed canary grass, and reduction in wildlife habitat.
(2)
Wetlands, natural. Natural wetlands are still in their natural state and typically show little
sign of impact from surrounding land usage. The vegetative communities of these wetlands
are characterized by a diversity of plant species with mixed dominance of species. Other key
factors include: presence of natural indicator species, good wildlife habitat, and being
aesthetically pleasing.
(3)
Wetlands, pristine. Wetlands that exist in a natural state and have special and unusual
qualities worth protecting at a high level are called pristine. These qualities include:
outstanding vegetation community, native species population, rare or unusual species present,
and habitat for rare wildlife species.
(4)
Utilized. Utilized water bodies created for the specific purpose of surface water runoff
retention and/or water quality improvements. These water bodies are not to be classified as
wetlands even if they take on wetland characteristics. Wetland alteration permits shall not be
required to undertake work on these water bodies."
(5)
Calcareous Fen. A calcareous fen is a peat-accumulating wetland dominated by
distinct groundwater inflows having specific chemical characteristics. The water is
characterized as circumneutral to alkaline, with high concentrations of calcium and low
dissolved oxygen content. The chemistry provides an environment for specific and
often rare hydrophytic plants.
Section 2. Section 20-406 Wetland buffer strips and setbacks shall be modified by
adding the following:
(c) For lots of record containing or abutting a calcareous fen, the following minimum provisions
are applicable:
(1) Structures shall maintain a minimum setback of 150 feet; and
(2) Prairie buffer shall be established and/or maintained within the entire 150-foot setback.
Section 3. This ordinance shall be effective immediately upon its passage and publication.
PASSED AND ADOPTED by the Chanhassen City Council this day of
· 2001.
ATTEST:
Todd Gerhardt, Acting City Manager
Linda C. Jansen, Mayor
(Published in the Chanhassen Villager )