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Composite photograph of a bioretetion swale, vegetated swale, and impervious pavement 

 

 As a result of the North Coast Regional Water Quality Control Board's (Regional Board) recent adoption of the Santa Rosa area's new NPDES storm water permit (Order No. R1-2009-0050) the regulations relating to storm water are changing.  This permit regulates both storm water and non-storm water discharges into the Santa Rosa municipal storm drain system with the intent to reduce storm water pollution and protect the water quality of our local creeks and waterways and continue to promote groundwater recharge.

Effective January 1st, 2010 the City of Santa Rosa will be requiring Low Impact Development (LID) Best Management Practices (BMPs) for all new development and re-development projects requiring post-construction storm water treatment BMPs.  Link here for the LID Technical Design Manual with the information and tools to guide its use.

Other important changes to note; projects that have not received Tentative Map approval (or equivalent) by June 1, 2010 will fall under the new sizing threshold requirements. After June 1, 2010 projects that create or replace 10,000 square feet of impervious area will require post-construction storm water BMPs and fall under the SUSMP requirements. The list of qualifying projects and exemptions from the NPDES Permit is shown here.

City staff is committed to helping our customers implement these new requirements.  If you have questions about this information, please contact Heaven Moore at (707) 543-4530.

 New Look at Storm Water

Traditional stormwater management practices focus on the collection and rapid removal of rainwater away from the point of impact, through a system of underground pipes and storm sewers, transferring water directly to creek outfalls without any sort of pre-treatment. The primary focus is to reduce or control localized flooding. The water collected by these extensive systems is viewed as a waste product to be disposed of. This approach generates vast quantities of polluted runoff, disrupts the natural hydrologic cycle, and adds to the contamination and scouring of streams and rivers.

In contrast, "green" or LID stormwater best management practices (BMPs) treat storm water as a resource to be preserved and maintained.  Stormwater BMPs focus on retention and infiltration of rainfall to maintain a natural water balance. Slowing the movement of water reduces problems with erosion and increases the chance for on-site filtration and purification of storm water. This is often accomplished by using vegetated areas and the natural purification of soil and plants.

Photographs of Green Street examples of bioretention swales, and pervious areas.

 Slow it Spread it Sink it

 

 What is LID?

With respect to storm water concerns, Low Impact Development (LID) is defined as a design strategy to maintain or reproduce the way storm water infiltrates or runs off a site before development occurs.  LID principles control storm water runoff by using small scale landscape based features that are distributed throughout the site. Projects designed following LID principals must maintain the undeveloped volume of storm water runoff  and mimic the natural water balance through infiltration, evapo-transpiration, or through capture and reuse of storm water.

 Typical Hydrological Cycle

Graphic showing amount of runoff of water before and after development.

 Goal of Regulations:

(a) Minimize the adverse impacts from storm water runoff on water quality, the biological integrity of receiving waters, and the beneficial uses of water bodies.
(b) Minimize the percentage of impervious surfaces on land development projects and implement mitigation measures to mimic the pre-development water balance through infiltration, evapotranspiration, and capture and reuse of storm water.
(c) Minimize pollutant loadings from impervious surfaces such as roof-tops, parking lots, and roadways through the use of properly designed, technically appropriate BMPs (including source control BMPs or good housekeeping practices), Low Impact Development strategies, and treatment control BMPs.
(d) Properly select, design and maintain treatment control BMPs and hydromodification control BMPs to address pollutants that are likely to be generated by land development, minimize post-development surface flows and velocities, assure long-term functionality of the BMPs, and avoid the breeding of vectors.

 

Drains to creek no dumping decal showing bird and fish in a creek.