Stormwater Pollution

What is Stormwater Pollution?

Stormwater (including urban runoff), pollution occurs whenever water containing pollutants, such as pesticides, fertilizer, pet waste, and litter enters the storm drain system. Storm drains are designed to prevent flooding from taking place, but they can also convey unwanted pollutants into our waterways.

View Stormwater Pollution Prevention Video

What is the Difference Between the Storm Drain System and the Sanitary Sewer System?

Every time you use the shower, sink, toilet, etc. the water you use goes through the sanitary sewer system treatment. The primary difference between the two drainage systems is that the sanitary sewer system goes through a number of wastewater treatment processes before the water it carries enters the waterways.

On the other hand, water that passes through the storm drain system remains completely untreated! Storm drains funnel water away from the cities and into the waterways in order to prevent flooding. The water that flows through the storm drain system carries along with it pollutants (e.g. pesticides, fertilizers, litter) that are being led directly into Newport Bay without any treatment.

Where Does Stormwater Go?

In the City of Irvine, stormwater carries pollutants from the storm drains into the San Diego Creek and eventually into Newport Bay,

What are the Effects of Stormwater Pollution?

Stormwater and urban runoff pollution has a detrimental effect on marine life, seafood, beachgoers, tourism, and other beneficial uses of our streams, bays, and ocean.

  • The Algalita Marine Research Foundation has found that there is six times more plastic in the ocean, by weight, than there is plankton. This influx of plastic is having a detrimental effect on the ecosystem and the diet of marine mammals and birds.
  • The effects of stormwater pollution are especially pronounced after it rains. You’ll notice that beach closures are in full effect after a rain because of the urban runoff that was led into the waterways by the storm drain system.

Check to see how your local beaches scored by visiting the Heal the Bay website.

What are Some of the Ways I can Prevent Stormwater Pollution?

  • Always throw your trash away in a waste receptacle or a recycling bin. Never throw trash on the ground.
  • Always follow manufacturer instructions when using fertilizers and pesticides. This helps prevent excess product from being carried off your lawn and into the streets and storm drains.
  • Always pick up after your dog to help prevent harmful bacteria from entering the storm drains.
  • Learn more about preventing stormwater pollution by visiting