Where Does My Water Come From And How Is It Treated?
Novato drinking water comes from two sources: A groundwater aquifer adjacent to the Russian River, and Stafford Lake. Additionally, recycled water is used for irrigation and some commercial applications.
NMWD purchases approximately 80% of its supply from Sonoma County Water Agency (SCWA). The SCWA water is collected 60 to 100 feet below the gravel beds adjacent to the Russian River. Extensive testing of this water has been conducted under the guidance of the California State Department of Drinking Water (DDW). The testing demonstrates conclusively that the natural filtration of this water is so effective that further treatment is not necessary. A small amount of chlorine is added to keep the water in the pipeline free from harmful bacteria and a small amount of sodium hydroxide is added to raise the pH in order to minimize corrosion of pipes.
Russian River water is conveyed to the District’s Novato Water System via a 7.1 mile long aqueduct, known as the North Marin Aqueduct (NMA). The aqueduct consists of a large diameter pipeline, ranging in size from 30-inch to 42-inch diameter, which is constructed of welded steel pipe. The NMA follows the Highway 101 corridor between Marin and Sonoma Counties and ultimately connects to the Sonoma County Water Agency’s aqueduct facilities in Petaluma. The NMA was originally constructed in the 1960s but as part of the early stages of the Marin-Sonoma Narrows widening project for Highway 101, the Sonoma County portion and approximately half of the Marin County portion of the original NMA was replaced with new pipe in 2014. Marin Municipal Water District also receives Russian River water via the NMA and has a separate aqueduct that brings that water through the Novato area bypassing the District Novato Water distribution system.
Stafford Lake Water Treatment Plant
Approximately 20% of Novato’s water supply comes from Stafford Lake. The Stafford Lake Water Treatment Plant is typically operated in the late spring through early fall to supplement NMWD’s purchased water supply. The amount of Stafford lake water used during the year depends upon the storage level attained from the previous winter’s rainfall.
Full treatment of Stafford lake water is required because it is a surface water source. A major renovation of the Stafford Lake Water Treatment Plant was completed in 2006, providing a host of new treatment tools to ensure water purity and to meet and exceed new surface water treatment regulations and requirements.
The water is first treated with chlorine dioxide to oxidize naturally-occurring organic and inorganic compounds and organisms. The water then undergoes an enhanced coagulation process and is filtered to remove any remaining suspended solids, making the water crystal clear. The water then passes through a series of granular activated carbon filters that remove dissolved organic molecules like those that can cause any unpleasant taste and odor. Next, a small amount of chlorine is added to the finished water to maintain a safe disinfectant residual as the water is distributed throughout the Novato water delivery system. Finally, a small amount of sodium hydroxide is added to raise the pH of the Stafford Lake water to minimize pipe corrosion. The water is now sparklingly clean, healthy, and great-tasting.
Treated Stafford lake water mixes well with the Russian River supply to provide the people of Novato with safe, high-quality and aesthetically-pleasing water.
What are Annual Water Quality Reports?
Water Quality Reports (or Consumer Confidence Reports) summarize the previous year’s monitoring and test results to show what substances have been found in the drinking water and whether the water is safe to drink. A useful site for understanding the information provided in the report is located at: www.waterqualityreport.org. The 1996 Amendments to the Safe Drinking Water Act has provisions requiring drinking water suppliers to issue annual reports to their customers on the quality of their drinking water.
If you ever have any questions about the quality of water that North Marin provides, please contact our Water Quality staff at (415) 761-8929 for additional information.