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HomeMy WebLinkAboutBozeman, MT UDC_38.410.100_Watercourse Setback_04-20-20214/20/2021 Bozeman, MT Code of Ordinances 1/6 A. 1. a. (1) (a) (b) (2) (3) 2. a. b. (1) (2) Sec. 38.410.100. - Watercourse setback. Where a development is crossed by or is adjacent to a watercourse, the developer must mitigate the impacts of the development on the watercourse. This mitigation may not be less restrictive than the requirements of the city floodplain regulations or any other applicable regulation of this chapter. The purpose of this mitigation is bank stabilization; sediment, nutrient and pollution removal; and flood control. Setback for developments granted preliminary plan or plat approval prior to July 10, 2002. These provisions apply to all developments granted preliminary plan or plat approval prior to July 10, 2002, including applicable subdivision exemptions: Setbacks. A minimum 100-foot setback must be provided along both sides of the East Gallatin River. A minimum 35-foot setback must be provided along both sides of all other watercourses. A portion of the required setback, immediately adjacent to the ordinary high water mark, must be left in a natural vegetative state as follows: East Gallatin River—50 feet. Other watercourses—Five feet. No fence, residential or commercial structure, fill material, parking or other similar improvements shall be located within required watercourse setbacks. All watercourse setbacks must be measured from the ordinary high water mark as defined in section 38.700.140. When no ordinary high water mark is discernible, setbacks must be measured from the top of the stream bank. Setbacks for developments granted preliminary plan or plat approval on or after July 10, 2002. These provisions apply to all developments granted preliminary plat or plan approval on or after July 10, 2002: In the event a site with an existing development, that is subject to subsection 1 of this section, is submitted to the city for a review subject to divisions 38.230, 38.430 and 38.280 of this chapter after July 10, 2002, the proposed development must comply with this subsection 2 to the extent reasonably feasible given the existing site conditions. The final approval body for the proposed development must determine the extent that is reasonably feasible, subject to any appeal provisions that may apply. Such administrative relief must not reduce setbacks below those provided for in subsection 1 of this section. In addition to any relaxation of watercourse setbacks provided by subsection 2.a of this section, nothing in this section prohibits an owner of affected property from: Applying for a variance to dimensional standards of the watercourse setbacks as allowed by and subject to the requirements of division 38.250 of this chapter; When applicable, seeking a deviation to dimensional standards of the watercourse 4/20/2021 Bozeman, MT Code of Ordinances 2/6 (3) (4) (5) (6) c. (1) (2) (3) (4) (a) (b) (c) (d) (5) d. e. setback as allowed by and subject to the requirements of divisions 38.340 or 38.430 of this chapter; Combining two or more lots to assemble a larger and more usable parcel; Petitioning the state department of fish, wildlife and parks and the county water conservation district to seek the reclassification of the relevant watercourse as an irrigation facility not subject to the requirements of this section; After receipt of required permits, relocating the watercourse; or Pursuing any other lawful means of relief from the effects of this section. Setbacks. Unless otherwise specified in subsection 2.e of this section, the following setback requirements must be met: East Gallatin River. A minimum 100-foot setback must be provided along both sides of the East Gallatin River. Sourdough/Bozeman Creek and Bridger Creek. A minimum 75-foot setback must be provided along both sides of Sourdough/Bozeman and Bridger Creeks. Other watercourses. A minimum 50-foot setback must be provided along both sides of all other watercourses. All required watercourse setbacks must be extended as necessary to address these additional requirements. The setback must extend to the edge of any delineated 100-year floodplain if the floodplain is larger than the setbacks established in this subsection 2.c; The setback must include immediately adjacent wetlands (i.e., fringe). The buffer width must be extended by the width of the wetland; Areas with a slope greater than 33 percent do not count towards the width of the setback; and The setback must include connected wetlands. The buffer width must be extended by a minimum of 50 feet beyond the perimeter of the connected wetlands. All watercourse setbacks must be measured from the ordinary high water mark as defined in section 38.700.090. When no ordinary high water mark is discernible, setbacks must be measured from the top of the stream bank. No newly constructed residential or commercial structure, addition to an existing structure, fence, deck, fill material (other than that required for exempt uses), parking lot or other impervious surfaces, or other similar improvements may be located within required watercourse setbacks, unless approved through, and in conformance with, a variance or deviation process as authorized in this chapter. Exceptions. The watercourse setback is divided into two zones. Zone 1 consists of the 60 percent of the setback closest to the watercourse, and Zone 2 consists of the 40 percent 4/20/2021 Bozeman, MT Code of Ordinances 3/6 (1) (2) (a) (b) (c) (d) (e) (3) (a) (b) (c) (d) (e) (4) (5) of the setback furthest from the watercourse. On-site stormwater treatment facilities may be located in Zone 2. Trails and trail-related improvements may be placed within the required watercourse setback subject to the following provisions: Trails, and trail-related improvements such as benches and trail signage, may be placed in Zone 2; Limited, non-looping developed spur trails to the water's edge may cross all zones. Benches and limited informational/interpretive signage may be placed in Zone 1 at the terminus of spur trails; Due to topography, avoidance of wetlands, or other geographical constraints, portions of non-spur trails may need to be placed within Zone 1. Trail construction within Zone 1, inclusive of watercourse crossings and spur trails, per each side of the watercourse, may not exceed the length of 300 percent of the width of the applicable watercourse setback per 500 lineal feet of watercourse; All trails must be constructed to minimize bank instability, sedimentation, nutrient and pollution runoff. Trails must be aligned to minimize damage to plant and wildlife habitat; and Trails crossing the watercourse and trail-related bridge structures may be located within all zones provided that the appropriate local, state and federal permits are obtained. Streets, sidewalks, utility lines or similar public construction may be permitted within all zones for the purpose of crossing a watercourse or protecting public health and safety. The following practices must be observed: Crossings must be minimized to the greatest extent feasible; Crossings with direct angles (90 degrees) must be used to the greatest extent feasible instead of oblique crossing angles; Construction must be capable of withstanding 100-year flood events; The subdivision grading and drainage plan must be designed to prevent the discharge of untreated stormwater into a watercourse; and A bank stabilization plan for all public construction watercourse crossings must be prepared and approved by the city prior to site preparation and installation of the improvement. Outlets from stormwater treatment facilities may pass through all zones in order to discharge to the receiving watercourse, provided that all required permits are obtained. Control of noxious weeds is required and activities required within limits outlined in 4/20/2021 Bozeman, MT Code of Ordinances 4/6 f. (1) (2) (3) (4) (5) (6) (7) g. any approved noxious weed control plan may occur in all zones. Setback planting. A setback planting plan must be prepared by a qualified landscape professional, and must be reviewed and approved by the community development department prior to the commencement of development or site preparation. The plan must include a schedule, and plantings must be depicted on the plan as follows: Zone 1: Zone 1 must be planted with new or existing native materials suited for a riparian area based on the following calculations. One hundred percent of the disturbed areas of Zone 1 must be planted with a ground cover of native riparian sedges, forbs and grasses suited for the area. In addition, a minimum of one shrub for every ten linear feet and one tree for every 30 linear feet of the watercourse is required along each side of the watercourse. Grouping or clumping of trees and shrubs as appropriate in a riparian area is encouraged. Species that are appropriate to the soil hydrologic conditions (wetness of soil and depth to the water table) must be used. Tree and shrub species selected must be suitable for the climate and for planting in a riparian area with an emphasis on native species. The Natural Resources Conservation Service (NRCS), the state native plant society and the county local water quality district (LWQD) are good sources of landscaping materials and/or landscaping information. Zone 2: Disturbed areas of Zone 2 must be planted with new or existing native grasses suited for the area. Maintenance of the watercourse setback landscaping is required. If it can be demonstrated that irrigation is present for the trees and shrubs, and fencing is provided for the trees and shrubs, the number of required trees may be reduced to one tree for every 60 linear feet and one shrub for every 20 linear feet of the watercourse along each side of the watercourse. Planting materials are exempt from the size requirements of section 38.550.050.G.3. To prevent soil erosion and the invasion of noxious weeds, the watercourse setbacks on all land proposed for development must be covered with existing vegetation or must be seeded with native grasses as soon as seasonally feasible or prior to commencement of any site development or site preparation work. Native must mean those plants which are native to the Gallatin Valley. Use native grasses, forbs, sedges and other herbaceous plants in areas of disturbance (e.g., bridges, culverts, utilities installation, trails) within the watercourse setback. Native woody plantings are required in all zones in both disturbed and undisturbed areas. Except as otherwise allowed in subsections 2.e and f of this section, no disturbance of soils and existing vegetation shall occur in any zones. 4/20/2021 Bozeman, MT Code of Ordinances 5/6 3. a. b. Other provisions. The watercourse setback must be depicted on all preliminary and final plats and plans. These provisions do not apply to agricultural uses, including lands controlled in the conservation reserve program (CRP), and activities and structures that existed prior to the effective date of the ordinance from which this section is derived. Any agricultural uses, activities or structures established after the effective date of the ordinance from which this section is derived must comply with these regulations. An agricultural use, activity or structure is considered abandoned if not used for agricultural purposes for more than 180 consecutive days. Figure 38.410.100-1. 100 year oodplain.   Figure 38.410.100-2. Watercourse setback on a slope.   4/20/2021 Bozeman, MT Code of Ordinances 6/6 Figure 38.410.100-3. Watercourse Setback.   Figure 38.410.100-4. Wetlands.