7.11. SR 04-17-2017 - Laserfiche WebLink

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Memorandum To: Zach Carlton, Planning Manager From: Brandon Wisner, Stormwater Coordinator Date: March 21, 2017 Subject: OA 17-05 – Changes to the City’s Wetland Setback Ordinance _______________________________________________________________________ Since single family home construction has increased over the last few years, staff has ensured new proposed single family homes comply with the 45 foot setback from any wetland boundary or the ordinary high water level of constructed stormwater ponds. This 45 foot setback not only has a water quality benefit, but it also provides insurance that homes will not be impacted by high levels of surface water following increased precipitation amounts. I recommend that proposed single family homes and all structures (i.e., accessory structures) meet the 45 foot setback to ensure homes and neighborhoods are adequately protected. For single family home lots that were platted prior to 2006, some difficulties have surfaced over the last few years with respect to ‘usable’ area of a lot with current setback requirements. Currently the first 25 feet from a wetland boundary or ordinary high water level of a stormwater pond is required to be free of structures, fencing or landscaping/mowing. It is important to note that this setback does not apply to stormwater basins that do not hold water for more than 48 hours which are designed as infiltration basins. Infiltration basins are required for new developments unless the soils are not conducive for long term function. If the first 25 foot buffer strip is proposed to be reduced, I recommend that it should not be reduced less than 10 feet for landscaping/mowing and fences. However, all structures should maintain the 45 foot setback. The first 10 feet from all stormwater ponds and wetlands is not only an important transition area ecologically but also is an area that has saturated soils that are more susceptible to impact from construction, fertilizers, and landscaping. Also, if these areas are continually mowed, root structure can be diminished that can encourage soil erosion. If erosion occurs, the city may be responsible for maintenance of the area if a drainage and utility easement is present. Lastly, properties with agricultural animals should still be required to have the 25 foot buffer strip to ensure water quality is maintained for adjacent surface waters.