The mouth of the Russian River is open once again, allowing water that had backed up in the estuary last week, flooding the Jenner Visitor Center and nearby parking lots, to drain to the ocean.

The force of the dammed up water on Saturday broke through the natural sandbar that had sealed the river shut last month after the recent series of storms.

At one point last week the water came so high it spread partway onto Highway 1, closing the road to a single lane, local business owner Suki Waters said.

“It was like a lake,” said Waters, owner of WaterTreks, a kayak and raft rental company on Highway 1 in Jenner. “I was raised here in Jenner. Outside of extreme flood conditions throughout the Russian River, this is probably the highest I’ve seen it since I was 10 years old.”

The Sonoma County Water Agency, which manages the river estuary, had hoped to breach the sandbar early last week, as it does from time to time. But exceptionally high surf made it too dangerous to do so, and the river kept on rising until it flooded the Jenner Visitor Center perched at the river’s edge as well as surrounding parking lots for the post office and businesses on the south end of town.

Waters said emergency personnel were on the scene to steer motorists around the floodwaters on Saturday until the sand was broken through, creating its own hazards.

By that time, the river was backed up for miles and drained with an enormous power, she said.

It had become “a lake all the way up to Guerneville — 15 miles up. That’s a lot of volume of water to dump out,” Waters said.