For more information about recreation on Cherry Lake and the Tuolumne River corridor, call the Groveland Ranger District at (209) 962-7825. For questions related to the repair work at Cherry Reservoir, contact Hetch Hetchy Water and Power at (209) 989-2000.

Dam operators at Cherry Lake plan to continue emptying water out of the reservoir until the end of this month, when it will hold about 10,000 acre-feet of water and be more than 96 percent empty.

Billed as the largest reservoir in the Stanislaus National Forest when it’s full, Cherry Lake was holding about 8 percent of its total capacity as of Thursday, according to the state Department of Water Resources.

The draw-down at Cherry is necessary for repairs on butterfly valves and hollow jet replacements, said Suzanne Gautier with the San Francisco Public Utilities Commission.

Last winter, one of four high-flow release valves at Cherry experienced mechanical failure, Nina Negusse, also with the San Francisco Public Utilities Commission, said earlier this year. In addition, another two valves are scheduled for replacement.

Cherry Lake is about 45 miles east of Sonora via Forest Road 1N04, also known as Cottonwood Road, when it’s open.

“We are currently in the final stage of lowering the lake and anticipate continuing this process until the end of September,” Gautier said.

Cherry Lake is closed to motorized boating, and the boat ramp, dam and some portions of downstream areas below the dam are all closed to the public, Gautier said this week.

Repairs of butterfly valves are expected to be completed by mid-November, and Hetch Hetchy Water and Power staff will begin to refill Cherry Lake, Gautier said. Hollow jet replacements are expected to be complete in late January.

Motorized watercraft are restricted on Cherry Lake until repairs are finished, but canoes, kayaks and paddle boards may still be used on the lake, according to Stanislaus National Forest staff.

Staff with the Central Sierra Environmental Resource Center in Twain Harte say the draining of Cherry is less than ideal because by later this month, only a small percentage of the reservoir will still have water in it.

The goal is to retain enough water for fish to survive and to maintain good water quality, while shrinking the reservoir to its minimum pool, CSERC staff said in July.

“Those who are used to seeing Cherry Lake’s miles of water stretch from the dam north toward the Emigrant Wilderness will see the bare landscape that was cleared in the 1950s to create the reservoir,” CSERC staff said.

Old-timers who remember Cherry Creek before Cherry Dam was completed in 1956 have claimed filling the reservoir more than 60 years ago blocked normal paths of migratory deer, forcing them to find different routes around the lake and dam, CSERC staff said.

Perhaps this year, when most of the reservoir is dry and exposed, deer moving downslope from the Emigrant Wilderness and northern Yosemite will once again move in groups and clusters across what is normally the deep, impounded water of Cherry Lake, CSERC staff said.

Hetch Hetchy Water and Power officials hope normal weather patterns will help restore water levels at Cherry by summer 2018, Negusse said earlier this year.

The San Francisco Public Utilities Commission owns and operates Cherry Valley Dam as part of Hetch Hetchy Water and Power. Hetch Hetchy provides water to 2.7 million customers in the greater San Francisco Bay area and Groveland.

According to San Francisco Public Utilities Commission staff, water stored at Cherry is used to generate hydroelectric power at Holm Powerhouse, it serves as an approved standby water source for Hetch Hetchy, and when it’s full it provides recreation on the reservoir, in Cherry Creek and on the Tuolumne River.

Contact Guy McCarthy at gmccarthy@uniondemocrat.com or (209) 588-4585. Follow him on Twitter @GuyMcCarthy.

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