Stormwater runoff is flow that is generated from rain or snow that falls on hard surfaces (e.g., roof tops, driveways, roads, and parking lots). The flow (runoff) generated from these surfaces enters local streams, rivers, canals, and drainageways during and immediately following a storm event instead of soaking into the ground. This causes a problem because the ground can no longer act as a sponge absorbing water or filter pollutants. As a result, more water and dirtier water enters streams and rivers quicker resulting in flooding, erosion, and degraded water quality.
Urbanization greatly increases the amount of runoff generated (pictured below).
Image courtesy of Portland Bureau of Environmental Services
Why is it a Problem?
Stormwater 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 drain is discharged untreated into the waterbodies we use for swimming, fishing, and for providing drinking water (EPA 2003). As a result, anything that enters storm drains in the Bear Creek Watershed can flow into Bear Creek to the Rogue River to the Pacific Ocean. It's all connected!
Impacts of Stormwater
Stormwater runoff can have many adverse effects on plants, fish, animals, and people beyond flooding.
Sediment can cloud the water making it difficult or impossible for aquatic plants to grow. Sediment can also destroy aquatic habitats or cover (and smother) salmonid eggs.
Excess nutrients can cause algal 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. Low levels of dissolved oxygen are found in the Bear Creek Watershed at periods during the year, especially the summer.
Bacteria and other pathogens can wash into swimming areas and create health hazards. Bear Creek and the Rogue River Basin are listed under the Clean Water Act through the TMDL program for bacteria concerns.
Debris-plastic bags, six-pack rings, bottles, and cigarette butts washed into waterbodies can choke, suffocate, or disable aquatic life.
Household hazardous wastes like insecticides, 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.
(Selected Text from EPA 2003)
How Stormwater is Managed
Local stormwater management is based on regulations from the Clean Water Act under the NPDES Phase II Program. Management programs are designed to meet the six minimum control measures listed below. Many of the concepts incorporated are based on mimicing or reestablishing natural functions.
Six minimum control measures (click here for a link to fact sheets on EPA's website):
Public Education and Outreach
Public Involvement and Participation
Illicit Discharge Detection and Elimination
Construction Site Runoff Control (Erosion Prevention and Sediment Control)
Post Construction Runoff Control
Pollution Prevention/Good Housekeeping
For information on what local communities are doing, click here.