Where Does Stormwater Go?

Stormwater flows directly into our rivers, lakes, streams and the ocean or into a stormwater system through a storm drain.

Storm drains are frequently located in parking lots and along the curbs of roadways. The grate that prevents larger objects from flowing into the storm sewer system is called a catch basin. Once below ground, the stormwater flows through pipes, which lead to an outfall where the stormwater usually enters a stream, river or lake.

In some areas, the outfall may lead to a stormwater management basin. These basins control the flow and improve the quality of stormwater, depending on how they are designed. They can also recharge groundwater systems.

In some urban areas of the state, the stormwater and sanitary sewer systems may be combined. Here both stormwater and sewage from households and businesses travel together in the same pipes and are treated at sewage treatment plants except during heavy rains. During these occasions, both the stormwater and untreated sewage exceed the capacity of the treatment plant, and this overflow is directed into local waterways.