Federal officials are reopening Lake Berryessa’s Oak Shores area for swimming Saturday, after having closed it for a week to investigate conditions in the wake of three recent drownings.

The findings: Lower water levels in the reservoir are make swimming in the lake more treacherous for the public, Bureau of Reclamation officials say. The low levels create steeper drop-offs from the shoreline and expose offshore islands that appear close to the shore, but are farther away than they look.

“Because of these conditions, visitors — especially children — are strongly encouraged to wear life vests if entering the water,” Reclamation officials stated in a press release.

The Bureau manages much of the land surrounding the Lake Berryessa area either directly or through contracts with resorts.

Officials also warned that swimming was unsafe for visitors after they’ve been drinking alcohol and that swimmers are more likely to find trouble if they’re swimming in “very deep water.”

On Sept. 7, 8, and 10, three separate drowning incidents ignited concern among the public and the bureau.

On Sept. 7, a 23-year-old Guatemalan man drowned while attempting to swim to an island near the Foxtail Flat portion of the lake.

On Sept. 8, a 26-year-old Fairfield man drowned after trying to swim to an island from Acorn Beach.

On Sept. 10 a 40-year-old woman slipped under the water swimming in the Oak Shores area at Acorn Beach. She was pulled from the water unconscious and died the next day at St. Helena Hospital.