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3b Assumption Creek Setback 690 City Center Drive PO Box 147 Chanhassen, Minnesota 55317 Phone 952.937.1900 G~erd Fax 952.93Z5739 Engineering Depamno~t Fax 952.937.9152 Building Departmort Fax 952.934.2524 Web Site w ww. cM. cha nhassen, m,. us MEMORANDUM To: Todd Gerhardt, Acting City Manager From: Loft Haak, Water Resources Coordinator Date: July 10, 2001 Re: Assumption Creek Setback PURPOSE Following-a visit to the Assumption Seminary site and conversations with representatives from several governmental agencies on June 4, 2001, Planning Commissioners Sacchet and Kind requested that staff explore an increased setback for Assumption Creek to protect it from potential damage (water quality decrease, loss of ecosystem, loss of trout population). This memo provides background on Assumption Creek, precedents for increased setback requirements and a recommendation for a revision to the City Code. BACKGROUND Assumption Creek is located in the southern portion of Chanhassen, west of Bluff Creek Drive and south of the Hennepin County Regional Trail Corridor. It crosses under Highway 212, flows into the Raguet Wildlife Management Area and is a tributary of the Minnesota River in Shakopee. Assumption Creek is classified by the State of Minnesota as an Agricultural/Tributary River. The current setbacks for agricultural/tributary rivers shown on the Protected Waters Inventory Map for Carver County are as follows: 100 feet for unsewered structures, 50 feet for sewered structures, and 75 feet for sewage treatment systems and structures employing sewage treatment systems. Neither the State of Minnesota nor the City of Chanhassen (Attachment 1) requires buffer zones adjacent to agricultural or tributary rivers. The City of Cha~d~assen. A ~o'owing community with clean lakes, aualin, schooh, a charmine downtown, thdvin¢ bminesses, and beautilSd parks. A ~reat place to live, work, and day. Creek Setback Amendment July 10, 2001 Page 2 RATIONALE Assumption Creek is consistently identified as a high priority resource within the City of Chanhassen for several reasons: 1. Assumption Creek is one of 15 designated trout streams in the Metro Area with a naturally reproducing trout population. 2. Assumption Creek is one of the only streams in the Metro area with a native population of brook trout, i.e. it was never stocked with fish. There are two other brook trout streams in the Metro area: Valley Creek and Mill Stream, both located in Washington County. Assumption Creek is the only brook trout stream in Carver County and the only one in the West Metro. 3. Assumption Creek is of high quality because the majority of the subwatershed in which it is located has remained undeveloped. 4. The Seminary Fen is closely related to Assumption Creek and is an extremely important resource for both the City of Chanhassen and the State of Minnesota. The creek and fen depend on the same groundwater and need it to be cold, clean and full of minerals. The fen and the creek could exist separately from each other; .however, because they exist together, they are codependent: what impacts one impacts the other, and the loss of one would result in the loss of the other. OTHER TROUT STREAMS There are only two other brook trout streams in the Metro area: Valley Creek and Mill Stream, both located in Washington County. Eagle Creek is another designated trout stream within the Metro area. Valley Creek Valley Creek is a high quality brook trout stream in the City of Afton in Washington County. The base flow is 98% groundwater, so it is very dependent upon a clean, cold groundwater flow. Some areas around the creek are undeveloped, but some people live adjacent to the creek and mow right up to the bank. Afton has a structure setback for trout streams of 150 feet for sewage treatment systems, and 200 feet for unsewered structures. Afton also requires a 20 to 50 foot "No-Mow Zone" alongside trout streams (Attachment 2). Mill Streatn Mill Stream is another high quality brook trout stream in Washington County. It is subdivided into three stream reaches (Headwaters, Middle and Lower) based on geologic landforms, stream morphology and land uses. All three reaches are dependent upon groundwater flows. The Headwaters Reach has been minimally affected by human impact; however, the Middle and Lower Reaches have been greatly altered through pond additions and building construction. Creek Setback Amendment July 10, 2001 Page 3 Marine-on-St. Croix has not adopted more stringent setback regulations for Mill Stream than those required by the Department of Natural Resources (DNR). Marine-on-St. Croix does not currently have buffer zone requirements. Eagle Creek Eagle Creek, though it does not support a brook trout population, is another designated trout stream in the Metro Area and supports brown trout. It is located in the City of Savage, and runs from the westem part of the city to the Minnesota River. Eagle Creek is fed by groundwater discharge, and there is a water quality monitoring station run by the Met Council on the stream. The subwatershed area is mostly developed, and it contains residential, commercial, and industrial regions. Savage does not have a creek setback ordinance because the State of Minnesota owns 200 feet on each side of the creek. This area around the creek is maintained as a protective buffer. PERTINENT ITEMS Staff has identified the following items that should be taken into consideration as the City contemplates the adoption of an increased trout stream setback: 1. There is little precedent in the area of trout stream buffers. There is an ordinance in the City of Afton that requires a protective buffer around the trout stream through private property, but the other buffers are on city or state-owned land. 2. Though the setback will be more restrictive and thus serve to protect the creek, it will still allow development near the creek, and it acknowledges that development may take place if the land remains in private ownership. 3. The land on which Assumption Creek 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 10-acres density must be maintained. A portion of the land is zoned RR (Rural Residential). The minimum lot size for RR is 2½ acres and a 1-unit per 10-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 of Chanhassen has been encouraged to create a creek setback by the DNR, Friends of the Minnesota Valley, the U.S. Fish and Wildlife Service, the Lower Minnesota River Watershed District (LMRWD) and the Minnesota Land Trust. 5. Anything that affects the complex hydrological balance of precipitation, surface water flow and groundwater discharge that feeds water to the creek can lead to the creek's degradation. 6. According to the Center for Watershed Protection (CWP), located in Washington, 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 stream quality when the watershed development exceeds 10 to 15% impervious cover. Creek Setback Amendment July 10, 2001 Page 4 Currently, staff has estimated the amount of impervious surface in the watershed to be 5%. 7. Assumption Creek is a fragile, delicate system. It needs a constant supply of cold, clean groundwater to stay viable. Surface water only affects the flow; the creek is dependent upon groundwater. Changes in temperature can be lethal to trout: 72 degrees Fahrenheit is too warm for trout survival. 8. A setback of 100 feet is necessary for good quality maintenance and protection, according to an Iowa State University impact study. For adequate protection, a buffer would also be required. 9. A setback with a buffer requirement would minimize the intrusion by non-native plant species and preserve the habitat diversity and the integrity of the ecosystem. 10. According to a study conducted by the Minnesota Storm Water Advisory Group (MSWAG) in 1997, the minimum wetland buffer 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. According to the MSWAG, the best-suited riparian buffers are more complex combinations of herbaceous and woody native species suited to the area. 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. 12. The trout population in Assumption Creek is already very small. In surveys of the creek, there have been no trout found south of Highway 212, as larger fish from the Minnesota River eat the smaller trout. North of Highway 212 there has been no official survey. However, there have been reports of citizens catching trout while fishing in the creek. It is imperative that the condition of the creek is maintained so that the trout population can be preserved. In order to accomplish this level of preservation, the creek needs to be managed under a plan with the cooperation of the DNR, the LMRWD and the City of Chanhassen. RECOMMENDATIONS Staff recommends that the Planning Commission recommend the City Council approve the following motions: "Section 20-479 shall be modified to read: (d) Rivers and streams. 1. Agricultural: Minnesota River - From west city boundary to east city boundary. 2. Tributary streams: Bluff Creek- From Basin 10-209W to Basin 27-132P (Rice Lake). Creek Setback Amendment July 10, 2001 Page 5 o Lake Ann (10-12P) to Lake Susan (10-13P). Lake Susan (10-13P) to Rice Marsh Lake (10-1P). Lake Minnewashta (10-9P) to Lake Virginia (10-15P). Purgatory Creek- From Lotus Lake (10-16P) to east city boundary. Trout streams: Assumption Creek - From west city boundary to Minnesota River." and "Section 20481 shall be modified to read: (a) Placement of structures on lots. When more than one (1) setback applies to a site, structures and facilities shall be located to meet all setbacks. Structures and onsite sewage treatment systems shall be setback (in feet) from the ordinary high water level as follows: Classes of Public Waters Lakes Natural environment Recreational development Rivers Unsewered Sewered 150 150 100 75 Agricultural and tributary 100 Trout streams 125 STS 150 75 50 75 100 100 For trout streams, the first seventy-five (75) feet of such setback shall be maintained or established in a prairie buffer. One (1) water oriented accessory structure designed in accordance with section 20-482(e)(2)(b) of this article may be setback a minimum distance of ten (10) feet from the ordinary high water level." ATTACHMENTS 1. Chanhassen City Code, Section 20-479 through Section 20-481 2. Afton City Code, excerpts from Section 12-363 and Section 12-402 3. Proposed amendment gAengXlorikmemosXcreek setback - cc report.doc ZONING § 20-479 ~md subdivisions/plats, and final decisions granting variances or conditional uses under local shoreland management controls shall be sent to the commissioner's designated representative and postmarked within ten (10) days of final action. (Ord. No. 217, § 4, 8-22-94) fSec. 20-479. Shoreland classification system and land use districts. (a) Shoreland classification system. The public waters of Chanhassen have been classified below consistent with the criteria found in Minnesota Regulations, Part 6120.3300, and the Protected Waters Inventory Map for Carver/Hennepin County, Minnesota. Co) [Shoreland area defined.] The shoreland area for the waterbodies listed below shall be as defined in section 20-1 and as shown on the official zoning map° (c) Lakes. (1) Natural Environmental Lakes: Inventory LD. Number Harrison 10-8W Rice Lake 27-132P Rice Marsh Lake 10-1P St. Joe 10-11P Silver 27-136P (2) Recreational Development Lakes: Inventory LD. Number (2) Ann 10-12P Christmas 27-137P Hazeltine 10-14P Lotus 10-6P Lucy 10-7P Minnewashta 10-9P Riley 10-2P Susan 10-13P Virginia 10-15P '(d) .Rivers and streams. (1) Agricultural: Minnesota River--From west city boundary to east city boundary. Tributary streams: Bluff Creek--From Basin 10-209W to Basin 27-132P (Rice Lake). Lake Ann (10-12P) to Lake Susan (10-13P). Lake Susan (10-13P) tn Rice Marsh Lake (10-1P). Supp. No. 8 1193 § 20479 CHANHASSEN CITY CODE ~ Lake Minnewashta (10-9P) to Lake Virginia (10-15P). Purgatory Creek--From Lotus Lal/e (10-6P) to east city boundary. All protected watercourses in Chanhassen shown on the Protected Waters Inventory Map for Carver County~ a copy of which is hereby adopted by reference, not given a classification h~rein shall be considered "tributary". (Ord. No. 217, § 4, 8-22-94) Sec. 20-480. Zoning and water supply/sanitary provisions. (a) Lot area and width standards. The lot area (in square fee/,) and lot width standards (in feet) for single, duplex, triplex and quad residential lots created after the date of enactment of this ordinance for the lake and river/stream classification are as follows: (1) Sewered lakes--Natural environment: Riparian Lots Nonriparian Lots Area Width Area Width Single 40,000 125 15,000 90 Duplex 70,000 225 35,000 180 Triplex 100,000 325 52,000 270 Quad 130,000 425 65,000 360 (2) Sewered lakes--Recreational development: Ri~varian Lots Nonriparian Lots Area Width Area Width Single 20,000 90 15,000 90 Duplex 35,000 135 26,000 135 Triplex 50,000 195 38,000 190 Quad 65,000 255 49,000 245 Unsewered lakes--Recreational development: Riparian Lots Nonriparian Lots Area W'wIth Area Width Single 40,000 125 15,000 90 ' (3) River/stream lot width standards. There is no minimum lot size requirements for rivers and streams. The lot width standards for single, duplex, triplex and quad residential developments for the six (6) river/stream classifications are as follows: Tributary Agricultural No Sewer Sewer Single 150 100 90 Duplex 225 150 115 Supp. No. S 1194 ZONING § 20-481 Tributary Agricultural No Sewer Sewer · riplex 300 200 150 Quad 375 250 190 (4) Additional special provisions. Residential subdivisions with dwelling unit densities exceeding those in the tables in subsections (1), (2) and (3) can only be allowed if designed and approved as residential planned unit developments. Only land above the ordinary high water level of public waters shall be used to meet lot area standards, and lot width standards shall be met at both the ordinary high water level and at the building line. The sewer lot area dimensions in subsections (1), (2) and (3) can only be used if publicly owned sewer system service is available to the property. (Ora_ No. 217, § 4, 8-22-94; Ord. No. 240, § 13, 7-24-95; Ord. No. 240, § 13, 7-24-95) e~ 20-481. Placement, design, and height of structure. (a) .Placement of structures on lots. When more than one (1) setback applies to a site, structures and facilities shall be located to meet all setbacks. Structures and onsite sewage treatment systems shall be setback (in feet) from the ordinary high water level as follows: Classes of Public Waters Lakes Natural environment Recreational development Rivers Agricultural and tributary Sewage Structures Treatment Unsewered Sewered System 150 150 150 100 75 75 100 50 75 When a structure exists on a lot on either side, the setback of a proposed structure shall be the greater of the distance set forth in the above table or the setback of the existing structure. One (1) water-oriented accessory structure designed in accordance with section 20-482(e)(2)(b) of this article may be setback a minimum distance often (10) feet from the ordinary high water ,.level. Co) Additional structure setbacks. The following additional structure setbacks apply, regardless of the classification of the waterbody. Setback From: (1) Top of bluff; (2) Unplatted cemetery; (3) Right-of-way line of federal, state, or county highway; and Setback (in feet) 30 50 50 s-pp. No. 8 1195 § 20~181 CHANHASSEN CITY CODE Setback From: (4) Right-of-way line of town road, pub- lic streets, or other roads or streets not classified. Setback (in feet) 2O (c) Bluffirnpact zones. Structures and accessory facilities, except stairways and landings, shall not be placed within bluff impact zones. (d) Nonresidential uses without water-oriented needs. Uses without water-oriented needs shall be located on lots or parcels without public waters frontage, or, fflocated on lots or parcels with ~ublic waters frontage, shall either be set back double the normal ordinary high water level setback or be substantially screened from view from the water by vegetation or topography, assuming summer, leaf-on conditions. (e) Design criteria for structures. (1) High water elevations. Structures shall be placed in accordance with any flood plain regulations applicable to the site. Where these controls do not exist, the elevation to which the lowest floor, including basement, is placed or floodproofed shall be determined as follows: a. For lakes, by placing the lowest floor at a level at least three (3) feet above the highest known water level, or three (3) feet above the ordinary high water level~ whichever is higher; b. For rivers and streams, by placing the lowest floor at least three (3) feet above the flood of record, if data are available. If data are not available, by placing the lowest floor at least three (3) feet above the ordinary high water level, or by conducting a technical evaluation to determine effects of proposed construction upon flood stages and flood flaws and to establish a flood protection elevation. Under all three (3) approaches, technical evaluations shall be done by a qualified- engineer or hydrologist consistent with parts 6120.5000 to 6120.6200 governing the management of flood plain areas. If more than one (1) approach is used, the highest flood protection elevation determined shall be used for placing structures and other facilities; and c. Water-oriented accessory structures may have the lowest floor placed lower than the elevation determined in this item if the structure is construed of flood- resistant materials to the elevation, electrical and mechanical equipment is placed above the elevation and, if long duration flooding is anticipated, the structure is built to withstand ice action and wind-driven waves and debris. {2) Water-oriented accessory structures. Each lot may have one (1) water-oriented accessory structure not meeting the normal structure setback in section 20-481(a) if this water-oriented accessory structure complies with the following provisions: The structure or facility shall not exceed ten (10) feet in height, exclusive of safety rails, and cannot occupy an area greater than two hundred fifty (250) square feet. Detached decks shall not exceed eight (8) feet above grade at any point. S-pp. No. S 1196 ZONING § 20-481 b. The setback of the structure or facility from the ordinary high water level shall be at least ten (10) feet;. c. The structure or facility shall be treated to reduce visibility as viewed from public waters and adjacent shorelands by vegetation, topography, increased setbacks or color, assuming summer, leaf-on conditions; cl. The roof may be used as a deck with safety rails, but shall not be enclosed or used as a storage area; e. The structure or facility shall not be designed or used for human habitation and shall not contain water supply or sewage treatment facilities; and f. As an alternative for general development and recreational development waterbod- ies, water-oriented accessory structures used solely for watercraft storage, and including storage of related boating and water-oriented sporting equipment, may occupy an area of up to four hundred (400) square feet provided the maximum width of the structure is twenty (20) feet as measured parallel to the configura- tion of the shoreline. (3) Stairway, Iii'cs and landings. Stairways and lifts are the preferred alternative to major topographic alterations for achieving access up ad down bluffs and steep slopes to shore areas. Stairways and lifts shall meet the following design requirements: a. Stairways and lifts shall not exceed four (4) feet in width on residential lots. Wider stairways may be used for commercial properties, public open-space recreational properties, and planned unit developments; b. Landings for stairways and lifts on residential lots shall not exceed thirty-two- (32) square feet in area. Landings larger than thirty-two (32) square feet may be used for commercial properties, public open-space, and recreational properties; c. Canopies or roofs are not allowed on stairways, lifts, or landings; d. Stairways, lifts, and landings may be either constructed above the ground on posts or pilings, or placed into' the ground, provided they are designed and built in a manner that ensures control of soil erosion; e. Stairways, lifts, and landings shall be located in the most visually inconspicuous portions of lots, as viewed from the surface of the public water assuming Summer, leaf-on conditions, whenever practical; and f. Facilities such as ramps, lifts, or mobility paths for physically handicapped persons are also allowed for achieving access to shore areas, provided that the dimensional and performance standards of subitems a. to e. are complied with in addition to the requirements of Minnesota Regulations, Chapter 1340. (4) Significant historic sites. No structure shall be placed on a significant historic site in a manner that affects the values of the site unless adequate information about the site has been removed and documented in a public repository. (5) Steep slopes. The planning director shall evaluate possible soil erosion impacts and development visibility from public waters before issuing a permit for construction of Supp. No. 9 1196.1 § 20-481 CHANHASSEN CITY CODE sewage treatment systems, roads, driveways, structures, or other improvements on steep slopes. When determined necessary, conditions shall be attached to issued permits to prevent erosion and to preserve existing vegetation screening of structures, vehicles, and other facilities as viewed from the surface of public waters, assuming sumruer, leaf-on vegetation. (f) Height of structures. Ail structures in residential districts, except churches and nonres- idential agricultural structures, shall not exceed thirty-five (35) feet in height. (Ord. No. 217, § 4, 8-22-94) Sec. 20-482. Shoreland alterations. (a) Generally. Alterations of vegetation and topography shall be regulated to prevent erosion into public waters, fix nutrients, preserve shoreland aesthetics, preserve historic values, prevent bank slumping, and protect fish and wildlife habitat. (b) Vegetation alterations. (1) (2) Vegetation alteration necessary for the construction of structures and sewage treat- ment systems and the construction of roads and parking areas regulated by section 20-484 of this article are exempt from the following vegetation alteration standards~ Removal or alteration of vegetation is allowed subject to the following standards: a. Intensive vegetation clearing within the shore and bluff impact zones and on steep slopes is not allowed. Intensive vegetation clearing for forest land conver- _ sion to another use outside of these areas is allowable if permitted as part of a development approved by the city council as a conditional use if an erosion control and sedimentation plan is developed and approved by the soil and water conservation diStrict in which the property is located. b. In shore and bluff impact zones and on steep slopes, limited clearing of trees and shrubs and cutting, pruning, and trimming of trees is allowed to provide a view of the water from the principal dwelling site and to accommodate the placement of stairways and landings, picnic areas, access paths, beach and watercraft access areas, and permitted water-oriented accessory structures or facilities, provided that: 1. The screening of structures, vehicles, or other facilities as viewed from the water, assuming leaf-on conditions, is not substantially reduced; 2. Along rivers, existing shading of water surfaces is preserved; 3. The above provisions are not applicable to the removal of trees, limbs, or branches that are dead, diseased, or pose safety hazards; and 4. The clearing be limited to a strip thirty (30) percent of lot width or thirty (30) feet, whichever is lesser, parallel to the shoreline and extending inward within the shore and bluff impact zones. (Ord. ~No. 217, § 4, 8-22-94; Ord. No. 251, § 1, 4-8-96) Supp. No. 9 1196.2 § 3.2-363 AFl?ON CODE Trout T~ibutam3 Stream 5. Parks and historic sites S S 6. Extractive use N N 7. Single residential C C 8. Mining of metallic minerals and peat N N 9. Semipublic S S 10. Duplex S S 11. Industrial use N N 12. PUD N N be One-half the distance from the water's edge of any trout sU-eam to the closest point of any dwelling but not less than 20 feet nor more than 50 feet either side of the centerline, vegetative cutting of grass and shrubs shall not be permitted in order to maintain important shade and cover as well as to minimize sedimenta- tion of the trout creel Parcels currently nonconforming will be subject to section 12-57(a), (b) and (g). Any discharge from development affecting the creek shall not exceed the discharge rate prior to development, nor shall it increase the sedimentation in the (Code 1982, § 303.4.2) Sec. 12.364. Use, upgrading of inconsistent land use distr~cts. When an interpretation question arises about whether a specific land use fits within a given "use" category, the interpretation shall be made by the city council after a public hearing and a recommendation by the planning commission. When a question arises as to whether a land use district's boundaries are properly delineated on the official zoning map, this interpretation shall be made by the city council after a public hearing and a recommendation by the planning corn~n~ssion. (Code 1982, § 303.4.23) Sees. 1~-~'~---1~-400. Reserved. CD12:142 § 12-402 AFTON CODE Sec. 12-402. Placement of structures on lots. When more than one setback applies to a site, structures and fad_Aities must be located to meet all setbacks. On an undeveloped bluffiand or shoreland lot which has two adjacent lots, with principal dwelling stn'uctures on both such adjacent lots within 200 feet of the common lot line, any new structure shall be setback from the ordinary high water mark the average setback of such adjacent struct~u'es plus 40 feet or the min{mtll~ sts~dRrd setback, whichever is less. (1) Structure and 'on-site sewage'system setbacks (in feet) from ordinary high water level*. (2) Classes of Public Waters Lakes Natural Environment Recreational Rivers Tributary Trout streums Setbacks* Structures Sewage Treatment [f nsewered Systen[' - (feet) (feet) L 200 150 200 150 200 150 The~Uowingad~fionalstruct~esetbac~ appl~regar~essofthe~sfficafionofthe wa~rbod~ Setback From.' a. Top of bluff b. Unplatted cemetery Setback (in feet) 40 150' c. All other setback~ shall meet the zoning ordinance, art/cie II of this chapter. Development on a lot, any portion of which is within 75 feet of the ordinary high water mark of any unclassified body ofwater, shall be subject to a building and septic system setback of 75 feet from such ordinary high water mark. All other lot requirements shall be subject to the regulations of the zoning ordinance, article H of this chapter, for the basic zoning district in whi'ch the lot is located. Maximum site'coverage by .any structure and parking area ten percent or one-half acre, whichever is greater. (3) Structures and accessory facilities, except stairways and landings, must not be placed within bluff impact zones. (Code 1982, § 303.5.21) CD12:144 · 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 20-479 (d) Rivers and streams shall be modified to read: (d) Rivers and streams. 1. Agricultural: Minnesota River - From west city boundary to east city boundary. 2. Tributary streams: Bluff Creek- From Basin 10-209W to Basin 27-132P (Rice Lake). Lake Ann (10-12P) to Lake Susan (10-13P). Lake Susan (10-13P) to Rice Marsh Lake (10-1P). Lake Minnewashta (10-9P) to Lake Virginia (10-15P). Purgatory Creek - From Lotus Lake (10-16P) to east city boundary. 3. Trout streams: Assumption Creek- From west city boundary to Minnesota River. All protected watercourses in Chanhassen shown on the Protected Waters Inventory Map for Carver County, a copy of which is hereby adopted by reference, not given a classification herein shall be considered "tributary". Section 2. Section 20481 shall be modified to read: (a) Placement of structures on lots. When more than one (1) setback applies to a site, structures and facilities, shall be located to meet all setbacks. Structures and onsite sewage treatment systems shall be setback (in feet) from the ordinary high water level as follows: Classes of Public Waters Lakes Rivers Unsewered Sewered Sewage Treatment System Natural environment 150 Recreational development 100 Agricultural and tributary 100 Trout streams 125 150 150 75 75 50 75 100 100 For trout streams, the first seventy-five (75) feet of such setback shall be maintained or established in a prairie buffer. One (1) water oriented accessory structure designed in accordance with section 20-482(e)(2)(b) of this article may be setback a minimum distance of ten (10) feet from the ordinary high water level. Section 3. This ordinance shall be effective immediately upon its passage and publication. PASSED AND ADOPTED by the Chanhassen City Council this ,2001. day of ATrEST: Todd Gerhardt, Acting City Manager (Published in the Chanhassen Villager Linda C. Jansen, Mayor