Frequently Asked Questions


What is stormwater pollution?

Rain water that isn’t absorbed into the ground flows over various surfaces throughout the urban landscape before entering a storm drain. This water is considered stormwater. As stormwater flows over the urban landscape, it may pick up pollutants such as animal waste, automobile fluids, fertilizers, trash, and pesticides, which may then be carried into the storm drains where it flows untreated into the local waterways.


Why is stormwater pollution a problem?

Stormwater runoff is not treated before it reaches local streams, creeks, rivers, and the ocean. That means that any pollutants it carries with it, such as trash and chemicals, enter our waterways and may harm the people, fish, birds, and animals that use them. 


Remember: a sanitary sewer system and a storm drain system are not the same. Water that goes down a sink, shower, or other indoor plumbing drain flows to either a wastewater treatment plant or to a septic system for treatment. In contrast, water that flows into a storm drain is not treated.


How does stormwater pollution affect my community?

Any pollutants that stormwater picks up as it flows into the storm drain system may harm local waterways. Examples of these adverse impacts include:

  • Nutrients such as phosphorus and nitrogen can cause the overgrowth of algae resulting in oxygen depletion in waterways, which then kills the fish.
  • Chemicals from motor vehicles and pesticides and fertilizers may be poisonous to fish and other aquatic life.
  • Bacteria from animal waste can make lakes and waterways unsafe for wading, swimming, and fish consumption.
  • Trash can clog storm drains, causing flooded streets during storm events or flow into the waterways harming the wildlife and habitat.


How can I protect our water resources?

We’re glad you asked! Everyone in San Joaquin County has a vital role to play in helping reduce the potential impacts of stormwater runoff. 

The main principle to keep in mind is to keep pollutants out of stormwater. Be mindful of any substances present in your neighborhood and daily life that are potential stormwater pollutants and do your best to keep them out of storm drains and waterways.

For specific tips on protecting our waterways from stormwater pollution, please visit the following pages based on whether you are a resident, business, or involved in development or construction:

  • Residents: Learn how to reduce stormwater pollution in your yard maintenance, car maintenance, pet care, house cleaning, trash disposal, and more.
  • Businesses: Find stormwater pollution tips and requirements for building maintenance, landscape maintenance, pressure washing, and more.
  • Development: Learn how to prevent stormwater pollution during the planning and development process.
  • Construction and Post-Construction: Learn how to prevent stormwater pollution during a construction project.