Land Use, Stormwater, and Water Quality

EPA- Local Government Land Use Planning

Urban Runoff: Model Ordinances to Prevent and Control Nonpoint Source Pollution

Many communities across the nation are facing challenges associated with natural resource degradation due to rapid growth and development. Local governments need to have legal authorities in place to shape development and to protect resources. This web site helps local governments by providing the necessary information needed to develop effective resource protection ordinances.

The ordinance types listed below include matters that are often forgotten in many local codes including aquatic buffers, erosion and sediment control, open space development, stormwater control operation and maintenance, illicit discharges and post construction controls.

The sortable example ordinance table allows visitors to select the relevant topic to see a listing of related real-life examples of ordinances used by local and state governments around the nation. View the sortable ordinance table.

The total volume of water remains the same under the different land use scenarios. What changes is simply the pathway of the water as it falls from the sky. In a built environment, more rainfall runs off surfaces rather than infiltrating into the ground, causing increased runoff. Some of the results of increased runoff are described below:

  • Reduced ground water recharge. Water that runs off, particularly if it is channeled through storm sewers, never has a chance to recharge ground water. This could be cause for concern, because 60% of drinking water in Indiana is provided from ground water, and ground water provides base flow to streams throughout the year.

  • Decreased base flow in streams. Base flow is the water that flows even during dry periods. Aesthetically, most people prefer to look at a stream that has water throughout the year rather than one that is periodically dry. More important, continuous base flow is vital to the health of aquatic life in the stream.

  • Increased erosion. Stream channel erosion is an important source of sediment in channels. Erosion is very dependent on flow. Doubling of the flow may cause the streambank erosion to increase by a factor of 4 or more.

  • Reduced natural filtration of the water. The process of passing through the soil is one of the most important purifiers of water. Many pollutants are filtered, attached to soil particles, or eaten by microbes as water passes through the soil. Bypassing this route has a severe negative effect on water quality.

  • Increased frequency and severity of flooding. If the runoff from a storm is greater, the chance of the flow exceeding the stream capacity and causing flooding increases.

  • Negative impact on stream health. Streamflow varies even under natural conditions, and most aquatic life is adapted to this. But increased streambank erosion due to higher peak flows and periods of very low flow due to the decreased base flow add stress for many organisms.

COOL TOOL! Hydrographs—A Tool for Stormwater Modeling

StormwaterPA fan and Philadelphia-based environmental engineer Adam Erispaha sent us an exciting new tool that he recently created. Hydrographs.com is an online tool for computing a stormwater runoff hydrograph over a single drainage area based on the curve number and SCS Unit Hydrograph hydrology.

EPA Offers a software download, the Storm Water Management Model (SWMM) The SWMM is used throughout the world for planning, analysis, and design related to stormwater runoff, combined and sanitary sewers, and other drainage systems. It can be used to evaluate gray infrastructure stormwater control strategies, such as pipes and storm drains, and is a useful tool for creating cost-effective green/gray hybrid stormwater control solutions. SWMM was developed to help support local, state, and national stormwater management objectives to reduce runoff through infiltration and retention, and help to reduce discharges that cause impairment of waterbodies.