Twain Harte Lake is closed for at least the rest of the summer while local and state officials figure out what caused part of the dam's footing to crumble Sunday.
A leak in the dam was reported about 10:45 a.m. Sunday after the large granite face that anchors the dam's southern side apparently cracked. Dam operators discovered water leaking through the cracked area, prompting emergency warnings of flash flooding downstream and brief fears of a dam failure.
The National Weather Service issued a flash flood warning for Sullivan Creek, which was later lifted after emergency personnel said there was no imminent danger of the dam failing. However, the watershed from Twain Harte all the way down to Don Pedro Reservoir will see above-normal flows in the coming days.
The Tuolumne County Administrator's Office reported this morning that the water is flowing smoothly through the watershed and spilling over the dam at Crystal Falls Lake. Tuolumne Utilities District is releasing water from Phoenix Lake to make room for the incoming water.
Twain Harte Dam operators started draining the small private swimming spot Sunday. It's expected to drop about 10 to 15 feet over two days - a move to relieve pressure behind the dam and allow more extensive examination of the damage.
The Twain Harte Lake Association, which owns the lake and the concrete-and-metal dam, has closed the lake until further notice.
The 12-acre body of water is typically open for summers and used for recreation by hundreds of vacationers and members, and the association annually employs dozens of lifeguards and other part-time employees at the lake.
Association General Manager Dennis Wyckoff said most of those employees had to be let go early, as the lake's season ended Sunday. However, Wyckoff also said he would beef up security staff at the lake to keep people away from the dam and water.
It was unclear Sunday if and when the association would be able to fill and use the lake again.
"We're done," Wyckoff said, referring to business for the summer.
For the complete story, see the Aug. 4, 2014, edition of The Union Democrat.