2017 Spencer Comprehensive Land Use Plan

Spencer, Iowa  2017  Comprehensive Plan

These pollutants can range from heavy metals to toxic chemicals, pesticides and herbicides, sediments, organic compounds, and other substances. The EPA has identified several storm water management practices that help alleviate direct storm water discharge into water bodies and allow a more natural dissolution of storm water runoff. Suggested practices include: • Erosion and Sedimentation Control Measures – After construction, the planting of fast growing vegetation such as grasses and wild flowers can prevent the runoff and erosion of construction sites. • Land Use Controls – Zoning and subdivision regulations can be utilized to keep encroaching developments from impeding upon drinking water sources, wetlands, marshes, streams or creeks. • Minimizing Directly Connected Impervious Areas – The reaction of water moving from one impervious surface to the next causes increased retention of sediment and contaminants into water bodies. For instance, water runoff from rooftops should be directed over grass instead of concrete. • Structural Designs – Are designed to create manufactured areas that retain or hold storm water runoff and allow for proper ground infiltration. Examples of structural designs are: 1) Grassy swales, 2) Buffer strips, 3) Filter strips or 4) Storm water retention ponds (wet ponds) • Constructed Wetlands – Similar to wet storm water ponds, however, they contain much more aquatic vegetation and natural plantings around the wetland. Constructed wetlands are intended to treat and retain stormwater and generally have less natural biodiversity than natural wetlands. • Infiltration Basins and Trenches – Long narrow stone-filled trenches, 3 to 12 feet deep where storm water runoff is stored and slowly infiltrates into the soil below, where filtering between the rocks and soil also helps to remove pollutants. Questions to ask when considering Development & Surface Water - Are there visual or other indications of water quality problems on or near the site? - Will the project involve discharge of effluent into surface water bodies? If so, will it meet state, federal, and other applicable standards? - Will the project involve substantial impervious surface waters? If so, have runoff control

measures been included in the design to insure protection of surface water? - Is the proposed project located in a watershed management plan area?

Questions to ask when considering Development & Storm Water - Will the proposed project disturb 1 acre or more of land? If yes, then an NPDES permit may be required. Contact an engineer to determine the need. - Will existing or proposed storm water disposal systems adequately serve the proposed project? - If no storm water system exists, will the project promote storm water run-off? If yes, then a project engineer should be consulted to determine ways to minimize impact.

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NW Iowa Planning & Development