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Plume of pollution and sediment at Doheny State Beach in Dana Point, CA

Stormwater is a term used to describe water that originates during precipitation events. It may also be used to apply to water that originates with snowmelt or runoff water from overwatering that enters the stormwater system. Stormwater that does not soak into the ground becomes surface runoff, which either flows directly into surface waterways or is channeled into storm sewers, which eventually discharge to surface waters and the ocean.

Stormwater is of concern for two main issues: one related to the volume and timing of runoff water (flood control and water supplies) and the other related to potential contaminants that the water is carrying, i.e. water pollution. Stormwater outfalls that discharge directly on a beach often create shallow streams or pools of water that are an "attractive nuisance." This water often has high concentrations of fecal indicator bacteria and may contain human pathogens. Contact with such water, especially by small children, should be avoided.

South Carolina stormdrain outfall and warning sign

Here's a short video demonstrating the effects of an inch of rain in Corpus Christ, Texas. Narration by six-year-old Jack.

See below for links to additional videos.

Agency Programs

EPA Stormwater Program
Stormwater runoff is generated when precipitation from rain and snowmelt events flows over land or impervious surfaces and does not percolate into the ground. As the runoff flows over the land or impervious surfaces (paved streets, parking lots, and building rooftops), it accumulates debris, chemicals, sediment or other pollutants that could adversely affect water quality if the runoff is discharged untreated. The primary method to control stormwater discharges is the use of best management practices (BMPs). In addition, most stormwater discharges are considered point sources and require coverage under an NPDES permit.

Stormwater Basic Information (EPA)

SWRCB Storm Water Program (California)
Several videos explaining what stormwater is and what can be done to lessen the effects of stormwater runoff.

SWRCB Nonpoint Source Program (California)

California Coastal Commission Water Quality Program Statewide Nonpoint Source

Caltrans Statewide Stormwater Program

Southern California Stormwater Monitoring Coalition
Stormwater runoff in southern California has become one of the largest environmental management issues in the region. The goal of the SMC is to develop the technical information necessary to better understand stormwater mechanisms and impacts, and then develop the tools that will effectively and efficiently improve stormwater decision-making. The SMC develops and funds cooperative projects to improve knowledge of stormwater quality management. SMC projects are described on these Web pages.

Bay Area Stormwater Management Agencies
BASMAA was started in response to the National Pollutant Discharge Elimination System (NPDES) permitting program for storm water in an effort to promote regional consistency and to facilitate efficient use of public resources.

Best Management Practices (BMPs)

NEMO National Network
The Network was originally envisioned as a cooperative of educational programs that would assist each other in fulfilling their mission of educating local decision makers. But as the Network has grown, it has begun to demonstrate that it can be far more than the sum of its parts, helping to leverage federal and state information, programs and dollars in a unique and effective way.

Low Impact Development LID Atlas

The International Stormwater Best Management Practices (BMP) Database
The International Stormwater Best Management Practices (BMP) Database project website, which features a database of over 400 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.


Industrial Stormwater Monitoring and Sampling Guide (EPA 832-B-09-003)

The Industrial Stormwater Monitoring and Sampling Guide (“guide”) is a how‐to primer for industrial facility operators on how to conduct visual and analytical monitoring of stormwater discharges. The target audience is operators of facilities subject to the U.S. Environmental Protection Agency’s (EPA) 2008 Multi‐Sector General Permit (2008 MSGP) or a similar State‐issued industrial stormwater permit. The information presented will also be useful to anyone interested in industrial stormwater monitoring. The procedures presented in this guide, specifically related to monitoring methodology and quality assurance, will help ensure that stormwater samples yield usable information.

Urban Stormwater BMP Performance Monitoring
This manual provides targeted practical assistance in conducting water quality monitoring and reporting data that are useful for assessing effectiveness of stormwater best management practices (BMPs).

Developing a Project Assessment and Evaluation Plan

How to do Stormwater Monitoring: A guide for construction sites (State of Washington)

The Stormwater Manager’s Resource Center
The Stormwater Manager's Resource Center is designed specifically for stormwater practitioners, local government officials and others that need technical assistance on stormwater management issues. Created and maintained by the Center for Watershed Protection.


After the Storm
The show highlights three case studies—Santa Monica Bay, the Mississippi River Basin/Gulf of Mexico, and New York City— where polluted runoff threatens watersheds highly valued for recreation, commercial fisheries and navigation, and drinking water. Key scientists and water quality experts, and citizens involved in local and national watershed protection efforts provide insight into the problems as well as solutions to today’s water quality challenges. More info.

Slow the Flow
Make Your Landscape Act Like a Sponge - A joint production of the Water Board Training Academy, Storm Water Program, brings to life practices and projects that individuals and communities have created to steward our watersheds and slow down the flow of storm water, one of the largest contributors of pollution into our waterways.

Video Highlights of a Unique Effort to Eliminate Plastic Debris
"Nurdles may sound harmless, but these small plastic pellets can do great damage to waterbodies like San Francisco Bay," said Jared Blumenfeld, EPA's Regional Administrator for the Pacific Southwest. "To protect our water resources, EPA is partnering with the State to require manufacturers to take steps to prevent pellet spills."


How to Talk About Polluted Stormwater

California Stormwater Quality Association
Formed in 1989 as the California Stormwater Quality Task Force, the SWQTF was a quasi-governmental organization, which advised the State Water Resources Control Board on matters related to developing stormwater regulations - more specifically, it was intended to help California comply with the municipal and industrial National Pollutant Discharge Elimination System (NPDES) stormwater mandates of the federal Clean Water Act. The Task Force officially became CASQA in September 2002, when its formal 501 (c)(3) non-profit organization status was approved. Today… CASQA holds bi-monthly meetings which are open to the public. Anyone can participate in committees and work groups.

Stormwater USA Online stormwater training & certification

National Association of Flood & Stormwater Management Agencies

Southeast Stormwater Association
SESWA is the source for up-to-date information on stormwater management for professionals in city and county governments and the consulting community throughout the southeast.