But most Central California reservoirs, preparing for the warmer weather and melting snowpack throughout the Sierra, have excess capacity to handle such runoff.
The Merced River is supposed to crest early Friday before receding throughout the day and into next week as temperatures cool.
The river was 10.8 feet above flood stage on Thursday and is expected to reach 12 feet above flood stage on Friday, said David Spector, a National Weather Service meteorologist in Hanford.
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In Yosemite, it’s expected that some low-lying campgrounds will flood, but they have already been closed in expectation of the excess warm weather melt off, said Spector.
“You don’t really start to see damage until you reach 12.5 feet and (the river) will crest at 12 feet,” he said.
The runoff is coming from the Sierra’s abundant snowpack. The season’s final snow survey was done on Monday, and it brought further evidence of winter’s bounty. State officials found 49.5 inches of snow and “snow water equivalent” of 27.8 inches. That amounts to 190 percent of average for May 1. The statewide snowpack average was 42.5 inches of snow water equivalent, or 196 percent of average.
The current flooding threat is the second time this year Yosemite has faced a rising Merced River. A mess of debris was left throughout the Valley in January during heavy storms, but no major impacts resulted.
The cold water rushing into rivers creates dangers for anyone venturing or falling into waterways. The body of a Bakersfield man was retrieved from the Tule River on Wednesday – the fifth drowning victim in a Tulare County river since April 14. The
Water from the Merced River flows into Lake McClure, east of Modesto, which is at 65.6 percent of capacity.
We probably have two-million more acre feet to come.
Michael Jackson, area superintendent for the federal Bureau of Reclamation in Fresno.
Other Central California lakes also have available capacity.
Steven Haugen, Kings River watermaster, said releases started in February created more capacity at Pine Flat reservoir east of Fresno. It was at 52.5 percent capacity on Thursday.
The earlier releases were done “to be able to safely pass those high flows when we got them.”
Meanwhile, Millerton Lake releases earlier this year also are accommodating more warm weather snow melt. Millerton, north of Fresno, was at 52 percent on Thursday.
“We have some buffer room to allow the reservoir to fill,” said Michael Jackson, Fresno area superintendent for the federal Bureau of Reclamation.
He said operations officials at Millerton will likely release 8,000 cubic feet per second in the coming weeks, which was exceeded earlier this year without flooding.
“We could probably go as high as 11,000 without flooding anybody, but we’re hoping we don’t have go over 8,000,” Jackson said.
He said the snow melt into the San Joaquin River could continue into July.
“We probably have two million more acre-feet to come,” Jackson said.