Stormwater Compliance

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Stormwater Compliance

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

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:

Evapotransporation
Infiltration
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)
Restaurants
Auto Service Facilities
Retail Gasoline Outlets

New Requirements Affecting Your 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.