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