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Polluted Runoff: Nonpoint Source Pollution

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.

Ordinance Type Overview includes 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.

Example Ordinances is a sortable table where you can select the relevant topic to see a listing of related real-life examples of ordinances used by local and state governments around the nation. 


Aquatic buffers serve as natural boundaries between local waterways and existing development. They help protect water quality by filtering pollutants, sediment and nutrients from runoff. Other benefits of buffers include flood control, stream bank stabilization, stream temperature control and room for lateral movement of the stream channel.

Good aquatic buffer ordinances specify the size and management of the stream buffer and are a specific planning tool to protect stream quality and aquatic habitat. Effective buffer ordinances provide guidelines for buffer creation and maintenance and should require:

  • buffer boundaries to be clearly marked on local planning maps
  • maintenance language that restricts vegetation and soil disturbance
  • tables that illustrate buffer width adjustment by percent slope and type of stream
  • direction on allowable uses and public education

A strong buffer ordinance is only a first step to preserving stream buffers. In addition, communities will need an effective buffer program to manage buffers and enforce buffer regulations. During the construction phase, communities need to ensure that the clearing and grading permit is well integrated with the forest buffer application. After construction, programs that educate citizens about the importance of the buffer and how to manage the buffer can help preserve its integrity.

Erosion and Sediment Control: By most accounts, the most environmentally dangerous period of development is the initial construction phase when land is cleared of vegetation and graded to create a proper surface for construction. The removal of natural vegetation and topsoil makes the exposed area particularly susceptible to erosion, causing transformation of existing drainage areas and disturbance of sensitive areas.

Erosion and sediment control is widely accepted as a necessary practice, but there are certain ways to make even the most well-crafted ordinance more effective. First, communities need to have the staff and resources to enforce erosion and sediment control regulations; otherwise, the authority to inspect sites becomes useless. In addition, the technical manual referred to in the ordinance needs to provide useful guidance on selecting erosion and sediment control measures. Third, education of contractors, engineers, and designers regarding the importance and effective use of erosion and sediment controls is essential to implementing effective erosion and sediment controls.

Open space development, also called "cluster development," is an alternative site planning technique that concentrates dwelling units in a compact area to reserve undeveloped space elsewhere on the site. In this technique, lot sizes, setbacks, and frontage distances are minimized to allow for open space. The typical open space development creates less impervious cover and reduces the need to clear and grade 35 percent to 60 percent of the site. Open space areas are often used for neighborhood recreation, stormwater management facilities, or conservation purposes. Open space preserved in a natural condition needs little maintenance and helps to reduce and sometimes to treat stormwater runoff from development.

Certain issues are not covered in this ordinance because many localities provide for them in other ordinances or they are too specific to each community. For example, language on road widths is not included because it is often a part of subdivision or other ordinances. Although most ordinances contain a section on the development review process, such language was not included because the review process varies widely by locality.

Although open space development is desirable, there are challenges to applying open space development criteria in every community. For open space development to be successful, the ordinance needs to be crafted in a way that fosters development that is both marketable and environmentally sensitive. The ordinance needs to effectively address issues such as maintenance, liability, and emergency vehicle access. In addition, the community needs to be prepared to manage the space or to dedicate open space to a responsible organization. Finally, decisions about when and where open space development is desired need to be made early.

Stormwater Control Operation and Maintenance: The expense of maintaining most stormwater best management practices (BMPs) is relatively small compared to the original construction cost. Too frequently, however, BMP maintenance is not completed, particularly when the BMP is privately owned. Improper maintenance decreases the efficiency of BMPs and can also detract from the aesthetic qualities of the practice. The operation and maintenance language within a stormwater ordinance can ensure that designs facilitate easy maintenance and that regular maintenance activities are completed.

Some important elements of effective stormwater operation and maintenance ordinance language are the specification of a specific entity responsible for long-term maintenance and reference to regular inspection visits. The ordinance should also address design guidelines that can help ease the maintenance burden, such as the inclusion of maintenance easements.

Although language that legally requires operation and maintenance of stormwater BMPs is important, there might be a disjoint between the ordinance language and what happens "on the ground." In this section, the information provided in support of the ordinance, such as maintenance agreements and inspection checklists, is as important as the ordinance to ensuring that stormwater BMPs perform efficiently over time.

An illicit discharge is defined as any discharge to the municipal separate storm sewer system that is not composed entirely of storm water, except for discharges allowed under a NPDES permit or waters used for firefighting operations. These non-stormwater discharges occur due to illegal connections to the storm drain system from business or commercial establishments. As a result of these illicit connections, contaminated wastewater enter into storm drains or directly into local waters before receiving treatment from a wastewater treatment plant. Illicit connections may be intentional or may be unknown to the business owner and often are due to the connection of floor drains to the storm sewer system. Additional sources of illicit discharges can be failing septic systems, illegal dumping practices, and the improper disposal of sewage from recreational practices such as boating or camping.

Illicit discharge detection and elimination programs are designed to prevent contamination of ground and surface water supplies by monitoring, inspection and removal of these illegal non-stormwater discharges. An essential element of these programs is an ordinance granting the authority to inspect properties suspected of releasing contaminated discharges into storm drain systems. Another important factor is the establishment of enforcement actions for those properties found to be in noncompliance or that refuse to allow access to their facilities.

Post Construction Controls: The management of stormwater runoff from sites after the construction phase is vital to controlling the impacts of development on urban water quality. The increase in impervious surfaces such as rooftops, roads, parking lots, and sidewalks due to land development can have a detrimental effect on aquatic systems. Heightened levels of impervious cover have been associated with stream warming and loss of aquatic biodiversity in urban areas. Runoff from impervious areas can also contain a variety of pollutants that are detrimental to water quality, including sediment, nutrients, road salts, heavy metals, pathogenic bacteria, and petroleum hydrocarbons.

Source water protection involves preventing the pollution of the groundwater, lakes, rivers, and streams that serve as sources of drinking water for local communities. Source water protection ordinances help safeguard community health and reduce the risk of contamination of water supplies. When drafting an ordinance aimed at protecting these sources, the drinking water supplies can be divided into two general sources; aquifers and wells (groundwater) and lakes and reservoirs (surface water). Wellhead Protection (WHP) Zones and Aquifer Protection Areas are two examples of source water protection ordinances that seek to protect groundwater sources. Water Supply Watershed Districts and Lake Watershed Overlay Districts are examples of local management tools that provide protection to surface water supplies by restricting land uses around a reservoir used for drinking water.

Communities may take for granted that a plentiful supply of high quality drinking water will be available. However, drinking water sources, whether they be from ground water, or surface water, or both, are a vulnerable natural resource that needs to be protected. To ensure that these drinking water sources are protected most effectively, an ordinance should contain several basic concepts. First, source water planning should be done on a scale that ensures protection of the whole recharge zones for that source water. For surface waters, communities may wish to create overlay zoning districts that have boundaries large enough to protect both the source water resource and the tributaries and streams that contribute to the resource. For groundwater, communities could consult with the USGS to be sure their overlay zoning district encompasses the entire area that recharges any aquifer. Second, an ordinance should have language specifying allowable and prohibited land uses within the source water protection zone. For example, many source water protection ordinances limit or forbid the storage of hazardous materials and place restrictions on the location of businesses that use these materials within the overlay district. An ordinance should also include procedures for review of proposed projects within a source water protection district to verify that the project is consistent with the ultimate goal of the ordinance. This might include requiring applicants to submit geotechnical and hydrological analyses to determine the potential impacts to water quality and the submission of spill control plans for businesses performing potentially contaminating activities. Finally, language explaining the mechanisms for enforcement of the requirements of the ordinance, including the civil and criminal penalties that may apply for failure to obey, should be included.

The source water protection ordinances are divided into two separate categories: a source water (groundwater) protection category and a surface water (reservoir) protection category. Each category contains a model ordinance and five example ordinances from around the country. The language for each of the models is borrowed from a number of ordinances and communities will need to assess what the appropriate requirements are for their area. In addition, some of the example ordinances have language addressing issues not dealt with in the model, and officials are encouraged to examine each of the ordinances for the best language to meet the specific needs of their community.

The Miscellaneous Ordinance examples capture ordinances that are important for protection of water resources but do not fall into the other categories of this site.

Helpful Resources

  • Local Government Environmental Assistance Network (LGEAN) Exit LGEAN's goal is to provide a forum and clearinghouse of environmental information for local governments. This site contains areas to explore new federal and state regulatory requirements and post messages and a search engine to help navigate their extensive library.

Local Government EnvironmentalAssistance Network

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Category Ordinance
Aquatic buffers Aquatic Buffer Model Ordinance
Aquatic buffers Buffer Protection and Management, Baltimore County, MD
Aquatic buffers Rhode Island Coastal Zone Program
Aquatic buffers Napa, California Riiparian Habitat Areas, 
Aquatic buffers Portland Metro Floodplain Preservation
Aquatic buffers Model Land Trust Agreement (Natural Lands Trust)
Erosion and sediment control Erosion and Sediment Control Model Ordinance
Erosion and sediment control Erosion and Sediment Control Ordinance from Minneapolis, MN
Erosion and sediment control Clearing and Grading Ordinance from Olympia, WA
Erosion and sediment control Erosion and Sediment Control Inspection Checklist from the Lower Platte South Natural Resources District, NE
Erosion and sediment control Small site design guideline from the Indiana Department of Natural Resources;
Erosion and sediment control Pre-Construction Meeting Notice from Montgomery County, MD
Open space development Open Space Development Model Ordinance
Open space development Open Space Development Ordinance from Calvert County, MD
Open space development Open Space Development Ordinance from Calvert County, MD
Open space development Land Preservation District Model Zoning from Montgomery County, PA
Open space development Open Space Ordinance from Hamburg Township, MI
Stormwater control operation and maintenance Stormwater Operation and Maintenance Model Ordinance
Stormwater control operation and maintenance Ordinance Language from Grand Traverse County, MI
Stormwater control operation and maintenance Example maintenance agreement from Albemarle County, VA
Stormwater control operation and maintenance Easement and ROW agreement from Montgomery County, MD
Stormwater control operation and maintenance Anne Arundel County, MD Inspection Checklist
Stormwater control operation and maintenance Performance Bond from Colorado
Illicit discharges Illicit Discharge and Connection Stormwater Model Ordinance
Illicit discharges Fort Worth, Texas Environmental Code-Stormwater Protection
Illicit discharges Washtenaw County, Michigan Regulation for Inspection of Residential Onsite Disposal Systems at Property Transfer
Illicit discharges Metropolitan St. Louis Sewer District Sewer Use
Illicit discharges City of Monterey, California Stormwater Ordinance
Illicit discharges Montgomery County, Maryland Illicit Discharge Ordinance
Post construction controls Post-Construction Stormwater Runoff Control Model Ordinance
Post construction controls Maryland Department of the Environment Stormwater Management Regulations
Post construction controls Grand Traverse County, Michigan Soil Erosion and Stormwater Runoff Control Ordinance
Post construction controls City of Seattle Stormwater, Grading and Drainage Control Code
Post construction controls St. Johns River Water Management District, Florida—Environmental Resource Permits
Post construction controls City of Santa Monica, California Municipal Code of Ordinances—Urban Runoff Pollution
Source water protection Ground Water Example Ordinance
Source water protection Surface Water Example Ordinance
Source water protection Creating a Wellhead Protection Area District from Oregon Exit 
Source water protection Model Aquifer/Wellhead Protection Ordinance from Tallahassee, FL
Miscellaneous Lake Travis Nonpoint Source Ordinance
Miscellaneous Stormwater Utility Ordinance from Takoma Park, MD
Miscellaneous Transfer of Development Rights Ordinance from Sarasota, FL
Miscellaneous Golf Course Management Guidelines form Baltimore County, MD
Miscellaneous Wetlands and Watercourses Ordinance from Croton-on-Hudson, NY
Miscellaneous Forest Conservation Ordinance from Frederick County, MD