3.0 – Urban Areas

With approximately 80 percent of the nation’s population living in coastal areas, controlling polluted runoff in urban areas is a challenge. Negative impacts of urbanization on coastal and estuarine waters are well documented in a number of sources, including California’s Clean Water Act section 305(b) and section 319 reports and the Nationwide Urban Runoff Program.

Major pollutants found in runoff from urban areas include sediment, nutrients, oxygen-demanding substances, road salts, heavy metals, petroleum hydrocarbons, pathogenic bacteria, viruses, trash, and plastics. Suspended sediments constitute the largest mass of pollutant loadings to receiving waters from urban areas. Construction is a major source of sediment erosion. Petroleum hydrocarbons result mostly from automobile sources. Nutrient and bacterial sources include garden fertilizers, leaves, grass clippings, pet wastes, and faulty septic tanks. As population densities increase, a corresponding increase occurs in pollutant loadings generated from human activities. Many of these pollutants enter surface waters via runoff without undergoing treatment.

The control of urban nonpoint source (NPS) pollution requires the use of two primary strategies: the prevention of pollutant loadings and the treatment of unavoidable loadings. California’s urban management measures are organized to parallel the land use development process to address the prevention and treatment of NPS pollution loadings during all phases of urbanization; this strategy relies primarily on the watershed approach, which focuses on pollution prevention or source reduction practices. Pollution prevention and source reduction practices are favored over treatment practices because conducting education practices and incorporating pollution prevention practices into project planning and design activities are generally more effective, require less maintenance, and are more cost-effective in the long term than treatment strategies. Treatment strategies should be used only to address unavoidable loadings or where they are truly cost-effective.

The Urban land-use category went through a major reorganization and several new, draft Management Measures (MM) were added to the previous 2006 edition of the NPS Encyclopedia. MM categories in the 2006 edition were based on the following water quality issues: Runoff from Developing Areas, Runoff from Construction Sites, and Runoff from Existing Development. These categories were consolidated into two, new MM categories: 3.1 - Planning and Design and 3.2 - Construction Practices (including the construction of transportation infrastructure). The purpose for this reorganization was to use categories based on common urban development phases so the end user (land developer, urban planner, transportation planner, municipal public works agency, flood control agency, or other urban water user) could easily access this information when implementing a project and/or addressing a water quality issue. In these new MM categories are subgroupings that reflect common areas of interest for the end users of this encyclopedia. .

These links provide more information for each of the following management measures


With respect to programs within the SWRCB and the RWQCBs, urban runoff is addressed primarily through the National Pollution Discharge Elimination System (NPDES) Permitting Program, although the SWRCB NPS Program will apply where the runoff is not regulated as a permitted point source discharge. The NPDES "point source" system of addressing urban runoff pollution is the result of the Water Quality Act of 1987, which amended the federal Clean Water Act to require NPDES permits for certain categories of storm water discharges. These "categories" of storm water discharges are described as follows:

  • Phase I of the Storm Water Program, defined in federal regulation in 1990, includes storm water discharges associated with "industrial" activities (as defined by the regulations), construction activities that disturb five acres of land or more, and discharges from municipal separate storm sewer systems (MS4s) serving populations of 100,000 people or more.
  • Phase II of the Storm Water Program, defined in federal regulations in 1999, expanded the program to require NPDES permits for discharges from construction sites disturbing between one and five acres, from small MS4s that serve populations of less than 100,000, from some other governmental facilities, and from industrial facilities owned by small municipalities. The expansion of the Storm Water Program through Phase II has therefore expanded the applicability of the NPDES point source program to a greater number of communities, businesses, government facilities, and industries. The result is that most urban runoff in California is now subject to NPDES permits.

The NPDES Program supersedes the SWRCB or RWQCB NPS Program in the areas where there is overlap. NPDES permits require implementation of management practices, which may or may not be similar to the management measures and management practices of the NPS Program. However, the SWRCB/RWQCB’s NPDES Program does not supersede the planning and land-use activities of other State agencies, such as the California Coastal Commission or the San Francisco Bay Conservation and Development Commission, which they are responsible for implementing under their own regulatory authorities. The SWRCB/RWQCB NPDES permits are at least as stringent as the NPS Program and will ensure at least the same level of compliance and water quality protection as the NPS Program’s management measures provide. Further, the authority of the SWRCB/RWQCB NPS Program will still apply for land use activities not covered by NPDES permits and for municipalities, construction sites, and industries that fall outside of the Phase I and Phase II Storm Water Programs.

Other Programs

  • California Department of Transportation (Caltrans), Statewide Storm Water Management Program integrates appropriate stormwater control activities into ongoing activities, thus making control of stormwater pollution a part of Caltrans normal business practices.
  • Surface Transportation Policy Project (STPP) provides assistance to local transportation agencies, elected officials, and citizen groups to help stakeholders take advantage of the new opportunities available under the federal transportation bill to link transportation to land use, housing, social equity, livable communities, and smart growth.
  • SWRCB, Clean Water Act section 401 Certification Program, RWQCBs review projects that require a federal permit under CWA section 404 or involve dredge or fill activities that may result in a discharge to waters of the United States. This is to ensure that the State’s interests are protected on any federally permitted activity occurring in or adjacent to waters of the State.

Information Resources

  • Caltrans Environmental Handbook, provides guidance on the identification and evaluation of the environment, including cultural resources (Volume 2), biological resource (Volume 3), community impact assessment (Volume 4), and guidance on storm water management (Volume 5) which is still in preparation.
  • Caltrans, Statewide Storm Water Management Plan was approved by the SWRCB in March 2003, describes procedures and practices Caltrans uses to manage pollutants discharged from storm water drainage systems.
  • Caltrans Stormwater Water Quality Planning Tool is a database of water quality standards and possible pollutants from Caltrans facilities. This unique tool is another valuable resource being used by Caltrans in its continuing commitment to prevent storm water pollution.
  • Center for Watershed Protection, Urban Stormwater Retrofit Practices, August 2007, outlines the basics of retrofits, describes the 13 unique locations where they can be found, and presents rapid methods to find, design and deliver retrofits to meet a wide range of subwatershed objectives.
  • Community Conservancy International (CCI), Green Solutions Project is a GIS-based collaborative project that determined areas with LID development opportunities for the Greater Los Angeles Area.
  • Environmental Enhancement and Mitigation Program offers financial assistance to government agencies and nonprofit organizations to fund projects aimed at reducing pollution associated with new or modified State transportation facilities.
  • G. Fred Lee and Associates, Stormwater Runoff Science/Engineering Newsletter is devoted to stormwater-runoff water quality issues in managing urban and agricultural stormwater runoff water quality impacts. The newsletter can be searched by topic or volume, and publications on other topics, including landfills, watersheds, contaminated sediment, reclaimed waters, hazardous chemicals, water quality, domestic water, and excess fertilization, can also be found on this site.
  • International Stormwater Best Management Practices (BMP) Database Project Website, features a database of over 300 BMP studies, performance analysis results, tools for use in BMP performance studies, monitoring guidance and other study-related publications. The overall purpose of the project is to provide scientifically sound information to improve the design, selection and performance of BMPs. Continued population of the database and assessment of its data will ultimately lead to a better understanding of factors influencing BMP performance and help to promote improvements in BMP design, selection and implementation.
  • Los Angeles County Structural BMP Prioritization Methodology is a new, systematic tool to prioritize structural BMP projects within Los Angeles County watersheds. This GIS-based method is designed to help watershed planners, managers, and stakeholders throughout LA County in strategic, conceptual planning of structural BMP placement. Funding for development of the Methodology was provided in part through an agreement with the State Water Resources Control Board (SWRCB) pursuant to the Costa-Machado Water Act of 2000 (Proposition 13) and any amendments thereto for the implementation of California’s Nonpoint Source Pollution Control Program. The project was conceived by Don Wolfe, Director of Public Works for the County of Los Angeles; Dr. Mark Gold, Executive Director of Heal the Bay; and Eric Strecker, Principal with GeoSyntec Consultants.
  • North American Lake Management Association (NALMA). 2007, Fundamentals of Urban Runoff Management is available to the public exclusively on the NALMS Website. You may download it in two versions: low-resolution and high-resolution. The low-resolution document is suitable for on-screen reading and lower-quality printing. The high-resolution version contains higher-quality graphics and is suited towards printing. T here is no printed copy planned at this time. If you have questions about the document or would like to be put into contact with one or more of the authors, please contact the NALMS staff.
  • Source Water Collaborative (SWC), Your Water.Your Decision guide is intended as a quick source of key information on local options for protecting drinking water, including development, stewardship, and budgeting. Using the theme, "how you govern can determine what you drink," the guide was developed as a tool to enable local officials to take action within their communities and with neighboring communities.
  • UC Davis Extension Center for Water and Land Use, mission is to increase awareness and understanding of the relationships between water resources and land use policies and practices through education, training, applied research, collaboration and dissemination of information.
  • USEPA, Nonpoint Source News-Notes is an online bulletin published by EPA that covers a wide range of topics, including nonpoint source pollution control, watershed restoration, and ecosystem-driven management. The Web interface allows users to search current and back issues of News-Notes by keyword.
  • USEPA, BASINS: Better Assessment Science Integrating Point and Nonpoint Sources is used for managing watersheds, integrates national watershed data and state-of-the-art environmental assessment and modeling tools into a geographic information system. The EPA Web site allows users to download the application and access documentation, metadata, frequently asked questions, training, an online forum, and other tools and utilities.
  • USEPA Storm Water Management Model (SWMM) is a dynamic rainfall-runoff simulation model used for single event or long-term (continuous) simulation of runoff quantity and quality from primarily urban areas. The runoff component of SWMM operates on a collection of subcatchment areas that receive precipitation and generate runoff and pollutant loads. The routing portion of SWMM transports this runoff through a system of pipes, channels, storage/treatment devices, pumps, and regulators. SWMM tracks the quantity and quality of runoff generated within each subcatchment, and the flow rate, flow depth, and quality of water in each pipe and channel during a simulation period comprised of multiple time steps.
  • U.S.Geological Survey (USGS) Hydrologic Simulation Program – Fortran (HSPF) simulates for extended periods of time the hydrologic, and associated water quality, processes on pervious and impervious land surfaces and in streams and well-mixed impoundments.
  • Washington State Department of Transportation (WSDOT), Soil Bioengineering provides information from designing projects to costs, funding, contractors, and native plant supplies. The site also showcases past projects and provides links to several online information sources.
  • WSDOT, Roadside and Site Development Unit began in 1990 with a review of state roadside policies and procedures by the Washington State Department of Transportation (WSDOT) Landscape/Roadside Reorganization Task Force. The Task Force recommended the development of clear policies and guidelines, and the coordination of planning, design, construction, and maintenance activities. The RCP provides those roadside policies and guidelines in coordination with the Transportation Policy Plan for Washington State, the Statewide Multimodal Transportation Plan, and Federal Highway Administration policies.
  • WSDOT, Roadside Manual provides guidance on roadside maintenance, including planning, design, construction, and maintenance. The manual has information on sustainable roadsides, environmental functions, wetlands, water quality, parking area design, erosion control, contour grading, soil bioengineering, and vegetative restoration concepts.

NPS Encyclopedia Site Map