Closed Russian River threatens low-level flooding in Jenner

High tides and heavy surf that closed Goat Rock State Beach for several hours Thursday and Friday mornings have delayed efforts by the Sonoma County Water Agency to open the mouth of the Russian River, potentially causing low-level flooding on Highway 1 in Jenner this weekend, the agency said.

Between the surging ocean surf and the rising river level, the band of beach across the river mouth has been reduced to a strip of land washed over by morning waves - conditions expected to persist until Monday, water agency spokeswoman Ann DuBay said.

Unless the river naturally breaches the sandbar this weekend, DuBay said, the water level will likely rise above flood stage of 9 feet in Jenner, potentially flooding the shoreline visitor center and even Highway 1, which dips to a low point at the center of town.

The river level already had risen above 8.8 feet by Friday afternoon, more than a foot above its elevation 24 hours earlier, DuBay said. The continued overwash of waves could mean the river rises even faster than anticipated, she said.

The water agency hopes to attempt to bring equipment onto the beach Monday to dig a channel at the river mouth, if one is still needed, she said.

The dimensions of the Russian River estuary change throughout the year as pressure from downstream flows and changes in ocean currents exert influence on the shoreline, building up and breaking down the sand berm at the river mouth.

When it’s closed, the water agency generally avoids intervening unless the river threatens to flood, and then only when it’s safe for heavy equipment and crews to operate in the area.

A planned attempt Friday was abandoned because the waves made conditions unsafe, DuBay said.

Between extreme high tide and large swells, the beach was almost inundated Thursday and Friday mornings around 8, the time park personnel would normally open the gate that allows entry to two lower parking lots at Goat Rock, park rangers said.

You can reach Staff Writer Mary Callahan at 707-521-5249 or mary.callahan@pressdemocrat.com. On Twitter @MaryCallahanB.