Stormwater runoff from urbanized areas remains the largest source of pollution to the San Francisco Bay and Coastal Waters. Local agencies in urbanized portions of the Bay Area are responsible for controlling stormwater pollution by complying with the new Municipal Regional Stormwater Permit (Stormwater Permit), issued by the State Regional Water Quality Control Board (Water Board) in October 2009.
Overview of Stormwater Requirements:
During Development Review, local agencies require projects to include stormwater controls, including site design measures, source controls, treatment measures, low impact development, hydromodification management and construction BMP's (Best Management Practices) as described below. Many of these requirements have existed for years and are unchanged.
Site Design for Water Quality:
Site design measures to reduce water quality impacts include:
- Reduce Impervious Surfaces
- Direct Runoff from Impervious Surfaces to Vegetated Areas
Source Controls for Water Quality:
Source controls present potential pollutant sources from contracting rainfall and stormwater. Examples include:
- Roofed Trash Enclosures
- Pest-Resistant Landscaping
- Sanitary Sewer Drains for Vehicle Wash Areas (with Waste Water approval)
Stormwater treatment measures are engineered systems that remove pollutants before stormwater reaches the storm drain system and ultimately the Pacific Ocean and local creeks and streams. Examples of stormwater treatment measures include:
- Bioretention Areas/Rain Gardens
- Flow-through Planters
- Vegetated Swales
Since 2006, projects that create and/or replace 10,000 square feet or more of impervious surface have required hydraulically-sized, post construction, stormwater treatment measures. Beginning December 1, 2011, new stormwater treatment requirements, as described below, will go into effect.
Effective December 1, 2011:
Stormwater treatment requirements will have to be met, using:
- Rainwater Harvesting and Reuse
- Where this is infeasible: Landscaped-based treatment measures with under drains may be used
The threshold for requiring stormwater treatment will drop from 10.000 square feet to 5,000 square feet or more of impervious surface for the following project categories:
- Uncovered Parking Areas (stand alone or part of another use)
- Auto Service Facilities
- Retail Gasoline Outlets
Will New Requirements Affect my Project?
If your permit application was deemed complete before December 1, 2009, and you "diligently pursue" the project, the new requirements do not apply. If a permit application is deemed complete after December 1, 2009, and final discretionary approval is received before December 1, 2011, the new requirements will not apply.
Blueprint for a Clean Bay
Engineering for Stormwater Compliance
Construction Stormwater BMP'S
Too Toxic to Trash
Guide to Creek and Wetland Project Permitting
Flows To Bay Community Webpage
Flows To Bay Business Webpage
Additional forms and handouts
Stormwater Points of Contact: