Local water agencies agree to extensive wastewater system improvements after Russian River spill

GUERNEVILLE, CA - The Russian River County Sanitation District and Sonoma Water will take immediate steps to improve the Guerneville wastewater system in connection with the spill of 5 million gallons of wastewater into the Russian River in January, under an enforcement settlement with the North Coast Regional Water Quality Control Board.

The spill began on Jan. 6 during severe storms and continued for three days after floodwaters entered the sewer collection system through unsecured maintenance access points and overwhelmed the Guerneville wastewater treatment facility. The resulting overflows from an aeration basin and emergency storage pond resulted in the release of an estimated 4.94 million gallons of untreated and partially treated wastewater into the river.

Sonoma County public health officials issued water-contact advisories for the river and several coastal beaches. The advisories remained in effect through Jan. 12.

The river is a source of drinking water, recreation and critical habitat for fish and wildlife.

The settlement requires the district and Sonoma Water to take a series of steps to reduce the risk of another spill — identify areas where floodwater is entering the sewer system, secure vulnerable maintenance access points and improve storm preparation and operating procedures. The North Coast Water Board retains authority to pursue additional enforcement if the requirements are not met.

“This agreement delivers immediate safeguards for the Russian River while building greater resilience for future storm seasons,” said Claudia Villacorta, assistant executive officer of the North Coast Water Board. “By improving pre-storm preparations, securing infrastructure vulnerable to flooding and expanding monitoring, the district and Sonoma Water are taking important steps to prevent another spill.”

Among the settlement requirements, the district and Sonoma Water must:

• Install temporary flow monitors to help identify areas vulnerable to flooding and locations where stormwater is entering the sewer system.
• Develop a corrective action plan addressing pre-storm preparations, operating procedures and improvements needed to make the treatment system more resilient during high-flow events.
• Assess maintenance access points that are vulnerable to flooding and make improvements to prevent floodwater from entering the sewer system.
• Complete a comprehensive study identifying sources of excess water entering the collection system and prioritize longer-term improvements.

Several of the initial plans and assessments in the order are due in September and October, with additional corrective work and reporting continuing through October 2027.

The North Coast Regional Water Quality Control Board protects and enhances water quality for the benefit of Californians, communities and the environment through planning, permitting, monitoring and enforcement.