What is Stormwater Runoff?


Storm water is the water that flows through gutters and into storm drains when it rains. During dry weather, water also flows into gutters and storm drains as a result of pavement washing, runoff from excess lawn irrigation, residential car washing, and other activities. Unlike the wastewater that flows through the sanitary sewer system to the Sacramento Regional County Sanitation District treatment facility, water that flows through the storm drain system is not treated. It is released directly to local waterways.

Rain water and dry-weather runoff pick up many kinds of pollutants as the water flows across pavement and landscaped areas and carries them into the storm water system and then to waterways. Trash, yard clipping debris, and other solid waste materials left in streets and gutters are also carried into the storm drain system. Because of these factors, urban runoff (also called nonpoint source pollution) remains the nation's largest source of water quality problems, according to the U.S. Environmental Protection Agency. 

Why is Stormwater Runoff a Problem?

Storm water can pick up debris, chemicals, dirt, and other pollutants and flow into a storm sewer system or directly to a lake, stream, river, wetland, or coastal water. Anything that enters a storm sewer system is discharged untreated into the waterbodies we use for swimming, fishing, and providing drinking water.

Pollutant means anything that causes or contributes to pollution.

Pollutants may include but are not limited to:

    • Sediment

    • Commercial & household carpet washing wastewater

    • Paints, varnishes & solvents

    • Motor oil & other automotive fluids

    • Non-hazardous liquid and solid wastes, refuse, rubbish, garbage or litter

    • Hazardous waste

    • Floatables

    • Pesticides, herbicides & fertilizers

    • Sewage

    • Animal wastes

    • Waste & residues from construction (sediments, slurries and concrete rinsates)


What are the Effects of Stormwater Pollution?


1.    Polluted storm water often affects drinking water sources. This, in turn, can affect human health and increase drinking water treatment costs.

2.    Polluted storm water runoff can have many adverse effects on plants, fish, animals, and people.

3.     Sediment can cloud the water and make it difficult or impossible for aquatic plants to grow. Sediment also can destroy aquatic habitats.

4.    Excess nutrients can cause algae blooms. When algae die, they sink to the bottom and decompose in a process that removes oxygen from the water. Fish and other aquatic organisms can’t exist in water with low dissolved oxygen levels.

5.    Bacteria and other pathogens can wash into swimming areas and create health hazards, often making beach closures necessary.

6.    Debris – plastic bags, six-pack rings, bottles, and cigarette butts – washed into waterbodies can choke, suffocate, or disable aquatic life like ducks, fish, turtles, and birds.

7.    Household hazardous wastes like insecticides, pesticides, paint, solvents, used motor oil, and other auto fluids can poison aquatic life. Land animals and people can become sick or die from eating diseased fish and shellfish or ingesting polluted water.


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 Sacramento Regional County Sanitation District waste-water facility. 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 city and into the local 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 local waterways such as the Sacramento River and the deep water ship channel.