The approaching rainy season requires that homeowners and contractors protect their construction sites against potential storm water runoff, especially in areas that experienced fire last year. The winter rain season typically lasts from October 1 through April 30. Annual rainfall varies between 30 inches in the lowlands to approximately 45 inches in the uplands. Depending on the severity of fire in burned areas, the runoff hydrology and erosion rates may drastically change compared to pre-fire conditions. Increased runoff, erosion, and transport of toxics from urban toxics may be significantly increased.
Sonoma County is working with the contractors engaged in building activities to protect the receiving waters from increased runoff due to construction activities throughout the County. Hydraulic mulch, silt fence, wattles, and erosion control blankets have been widely accepted as the best performing and effective Best Management Practices (BMPs) to protect sites from storm water runoff. Additionally Sonoma County Transportation and Public Works will be engaged in increased street sweeping and inlet cleanout to remove sediment from the roadways and inlets during the rainy season. Sonoma County is also providing information to owners of fire-impacted lots that are presently vacant but still could be a source of sediment from bare soils left after debris removal was completed.
All BMPs will be monitored for maintenance and adaptive management as the rainy season progresses. Homeowners can reference Permit Sonoma’s Construction BMP webpage for appropriate BMP measures to protect their sites.