Atmospheric river brings wastewater overflow in Sonoma

Crews were monitoring the impact on public and environmental health after 4 inches of rain flooded the sanitation systems.|

Sonoma Water has sent crews to respond to wastewater overflows at the Sonoma Valley County Sanitation District system and Penngrove Sanitation Zone after the heavy rain this weekend caused flooding.

Heavy rain this weekend dumped as much as 7.5 inches in parts of Sonoma Valley and almost 9 inches on Sonoma Mountain, causing the wastewater collections systems to overflow, according to Sonoma Water.

The overflows occurred on Highway 12 at Agua Caliente Creek, and all along Sonoma Creek at Burbank Drive in Glen Ellen; and on Rancho Drive, Cedar Avenue, and Casabella Drive at Valetti Drive in Sonoma. It was also detected at the Penngrove Lift Station in Penngrove.

“Overflows generally run into storm drains which then drain into nearby creeks,” Sonoma Water said in a press release.

Sonoma Water added that maintenance crews were sent to the sites in anticipation of the “heavy inflows” into the collection systems. The crews attempted to mitigate the inflow using pump trucks to divert water.

“The Sonoma Valley wastewater treatment plant is capable of treating up to 12 million gallons per day and storing up to 35 million gallons of untreated wastewater,“ the press release said, ”but during heavy rain events inflow into the plant can increase by as much as nine times the average flow.“

Sonoma Water posted signs at the overflow sites and notified the State Office of Emergency Services and the California Department of Fish and Wildlife of the overflow sites.

Contact Chase Hunter at and follow @Chase_HunterB on Twitter.

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