Crews working overnight were able to repair a 40-year-old steel-and-concrete pipe that burst in Guerneville, north of the Bay Area, sending 100,000 gallons or more of sewage into the Russian River.
Officials say it is the biggest sewage spill into the Northern California river in at least a decade.
About 40,000 gallons of sewage per hour generally flows through the 16-inch pipe, officials said. The leak near Branch and Orchard avenues started at about 12:30 p.m. Thursday and lasted about three hours.
Crews fixed the pipe overnight, a Sonoma County water official told the Santa Rosa Press Democrat.
A spokesman for the Sonoma County Water Agency said biologists found no environmental issues from the spill, but were continuing to evaluate the incident.
In 2002, state water officials temporarily shut down some water pumps because of a raw sewage spill into the Russian River.