FORESTVILLE (BCN) — With a major storm expected to hit the Bay Area Sunday, a rubber dam in the Russian River near Forestville will be deflated Saturday to prevent damage to the dam from high river flows, authorities said.

Sonoma Water, Sonoma County’s water agency, deflates the rubber dam when Russian River flow forecasts show the river reaching 2,000 cubic feet per second, the agency said. The atmospheric river bearing down on the Bay Area Sunday is expected to raise river flows above 19,000 cubic feet per second.

“The river right now is flowing at about 127 cubic feet per second,” said Barry Dugan, Sonoma Water public information officer. “But we anticipate by Sunday night, early Monday morning, it’s going to be at 19,000 cubic feet per second.”

The rubber dam is brand new. Saturday was the first day water flowed over it but, just like that, the bladder was quickly deflated to protect it from the torrent of water that was coming.

“The river can rise very quickly with a storm like this so we lower the dam — deflate the dam, technically — and it sits at the bottom of the river so it doesn’t get damaged by the high flows,” Dugan explained.

Inflatable Dam on Russian River

Inflatable dam on the Russian River near Forestville. (CBS)

The rubber dam is just downstream of the river’s Wohler Bridge and is usually raised in the spring or early summer when water demands increase. It creates a pool of water that enhances Sonoma Water’s well levels in the area, the agency said.

A permanent “fish ladder,” a seemingly oxymoronic phrase describing a structure that helps fish navigate obstacles, provides fish passage when the dam is raised. The fish ladder also allows Sonoma Water to count the migration of adult salmon and steelhead with its underwater video system in the fish ladder.

When completely deflated, the rubber dam rests flat on the bottom of the Russian River.

The agency noted that even with the recent series of storms, the region is well behind normal rainfall totals and reservoirs remain at historically low levels.

© Copyright 2021 CBS Broadcasting Inc. and Bay City News Service. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed. KPIX 5’s John Ramos reports