California Water Quality Rules for Development Projects

Provision C.3 of the NPDES

In February 2003, the California Regional Water Quality Control Boards for the San Francisco Bay Region and the Central Valley Region revised Provision "C.3" in the NPDES permit governing storm water discharges from in the City of Concord. The new permit provisions are phased in 2004 through 2006.

The new "C.3" requirements are separate from-and in addition to-requirements for erosion and sediment control and for pollution prevention measures during construction.

Project site designs must minimize the area of new roofs and paving. Where feasible, pervious surfaces should be used instead of paving so runoff can percolate to the underlying soil. Water runoff from impervious areas must be captured and treated.

Projects may also be required to detain or infiltrate runoff so that peak flows and durations match pre-project conditions. In addition, project applicants must prepare plans and execute agreements to insure that the storm water treatment devices are maintained in perpetuity.

Below are links to the Contra Costa Clean Water Program's 2-page and 4-page fact sheets that explain many of the new requirements. There are also links to the detailed guidance in the Stormwater C.3 Guidebook and its appendixes, other reference information on the Clean Water Program's web site, and to Planning's application checklist for projects that must comply with C.3.

Stormwater Guidebook

City of Concord CA