What is stormwater?

Stormwater is runoff from rain or snow that cannot be absorbed through surfaces like driveways, parking lots, roads, sidewalks, or roofs. As water travels over these surfaces, it may pick up dirt, trash, oil, grease, pesticides, fertilizers, pet waste, and other pollutants and carry them into local creeks and water bodies.

It’s important to mention that while most cities in the US have a separate sewer system where stormwater flows into a storm drain which leads into local waterways without treatment, other cities have a combined sewer system. This means that stormwater and wastewater are treated together at a wastewater treatment facility. Cities with a combined sewer system are concentrated in the Pacific Northeast and Great Lakes regions, examples include San Francisco, Portland, Chicago, and Minneapolis.


How do we regulate stormwater runoff?

The federal Clean Water Act was amended in 1987 to address urban stormwater runoff pollution of the nation’s waters. In 1990, the US EPA established the National Pollutant Discharge Elimination System (NPDES) stormwater program. This program has been delegated to state agencies to oversee this stormwater program. In California, this responsibility has been passed on to the State Water Resources Control Board and the nine Regional Water Quality Control Boards. These regulatory bodies issue NPDES permits to entities that discharge pollutants from a point source to a water of the United States.

At the local level, many cities, counties, and businesses have an NPDES permit that provides requirements which help reduce stormwater pollution in local water bodies. For cities, these requirements exist for municipal operations, construction activities, new developments, redevelopments, industrial sites, and illegal non-stormwater discharges. In addition, NPDES permits generally have a public outreach and a water quality monitoring component.


What are some ways to prevent water pollution?

Residents play a huge role in preventing water pollution into local water bodies. There are many simple actions that you can do to keep rivers, creeks, streams, or oceans safer. Here are ten ways that you can prevent water pollution.