Coyote Creek drains a watershed of 165 square miles, 85.5 square miles of which lie in north Orange County, with the remainder in Los Angeles County. The upper watershed contains some open space, most of which is used for oil production. However, most of the watershed is highly urbanized with a mixture of residential, commercial, and industrial development. Coyote Creek flows along the border between Orange and Los Angeles counties and finally flows into the San Gabriel River just above its tidal prism.
The Los Angeles Regional Water Quality Control Board (LARWQCB) found that metals loads in the San Gabriel River watershed, including Coyote Creek, may be harmful to aquatic life and impair the water supply. The LARWQCB Staff Report did not indicate any dry weather impairments in Coyote Creek. However, analysis of storm samples collected by the Los Angeles County Department of Public Works indicated too many exceedances of the copper, lead, and zinc chronic criteria from the California Toxics Rule.
At this time, the County of Orange and watershed cities are developing a work plan to reduce metals loads in Coyote Creek, as required by the Stormwater Permit, until a full implementation plan can be developed.