Urban Conservation As we look at urban erosion in Mills County there are some interesting numbers that show the rapid growth of new homes are part of increased urbanization occurring throughout the United States. During the period from 1982-1992 land was converted (throughout the United States) at 1.4 million acres a year; from 1992 to 1997 land was converted at 2.2 million acres a year. This rate is more than 1.5 times the previous 10-year rate. Between 1982 and 1997 the amount of urbanized land in the United States increased by 47%. During this same period the nation’s population grew by only 17%. In the Midwest there was a 32% increase in urbanized land compared to only a 7% increase in population (Source: Green Infrastructure Monograph). To understand the volume of water that will fall on this one acre site consider the following information. One inch of rain on an acre of land delivers 27,152 gallons of water. With our average of 32 inches annual precipitation, an acre of land receives 868,864 gallons per year. When best management practices are not used the results can be costly. Mills County is the fastest growing county in Western Iowa and especially in the Loess Hills. Oak Township in Mills County is the fastest growing township in the seven western counties of Iowa. Growth (urbanization) creates problems and opportunities concerning soil conservation. Building Site Selection When building a home or maintaining an existing property it is important to know what soils you are building on and have an understanding of how water drains from individual properties and within a neighborhood. Soils: Traditionally, soil is defined as a dynamic natural body that is made up solids, liquids and gases, occurs on the earth surface, contains living matter, and supports or is capable of supporting plants. “Urban Soils” are defined as soil material having an non-agricultural, man-made surface layer more than 20 inches thick that has been produced by mixing, filling, or by contamination of land surface in urban and suburban areas. In important ways, soils of urban areas differ from soils of other areas. Understand the soils you are building on. Mills County is comprised of different types of soils ranging from bottom land soils to loess soils. The Loess Soils have one of the highest erosion rates in the United States. Special care is needed when building on these soils. Consult the Mills County District office in understanding what will grow best on your site. You will want to consider factors such as soil fertility, seed or sod application rates and dates, rates on composting and mulches when establishing lawn and ground cover. Building Sites: Proper management of your building site is a positive way to let the public/neighbors know that you and/or your company care about the stewardship of our natural resources. The Erosion Control Plan Why develop an Erosion Control Plan (also known as a Pollution Prevention Plan)? It’s the law if you disturb 1 acre or more. (See National Pollution Discharge Elimination System rules) Erosion and sediment control Water quality issues Helps identify problem areas Gives tools for the general contractor Education benefits Saves time and resources Not to mention, it is the right thing to do. Planning, applying and maintaining a good erosion control plan will keep you in compliance and protect water resources. What is the difference between Erosion Control Practices and Sediment Control Practices? Erosion Controls are used to prevent soil erosion from occurring at sites with bare soils. Practices include: Mulch Compost Blankets Temporary and Permanent seeding Minimized Land Clearing Rolled Erosion Control Products (RECP’s) Sediment Controls are used to control eroded or eroding sediments and keep them on site and away from surface waters. Practices include: Silt Fences Geo-RidgesTM Sediment Basins Compost Berms Compost Socks Timing is critical to prevent accelerated erosion! Minimize the time soils are left exposed Reduce areas of exposed soil during rainy seasons Protect critical areas, streams, drainage channels Stabilize exposed areas quickly Basic points of the Storm Water Erosion Control Plan Plans shall be prepared in accordance with good engineering practices. Plan shall identify potential sources of pollution which affect the quality of discharge from the site. Plan shall describe and ensure the implementation of practices that will be used to reduce erosion. Content of the Erosion Control Plan (Pollution Prevention Plan) Nature of construction activity Total area of site to be disturbed Runoff coefficient of site after construction Site Map, slopes, water bodies etc. What practices to be installed and location and timeline Stabilization practices Structural practices Storm water management Other control, example dust, waste disposal, etc. Maintenance of practices Inspection reports (critical) Identify contractors and sub contractors Other Resources NRCS - Backyard (Urban) Conservation National Association of Conservation Districts (NACD) - Urban and Community Conservation Erosion Control Online - Articles and information on limiting the effect of erosion of all types. Iowa DNR - Stormwater Program Local Contacts Rich Maaske, Environmental Specialist for the Iowa Department of Agriculture and Land Stewardship - Division of Soil Conservation, assists homeowners, developers, and engineering firms in pre-and-post-construction projects. Rich is located in the Council Bluffs Field Office (712.328.2489), and works on issues within Mills and West Pottowatamie Counties.