Melting snow could affect water levels on the Mokelumne
The relentless procession of rain this past winter, coupled with record-breaking snow levels, has left the East Bay Municipal Utility District monitoring the Pardee and Camanche Dams around-theclock.
According to the California Department of Water Resources, this past winter has been recorded as the fourth wettest winter year on record for the region, dating back to the 1950s.
The DWR Phillips Station snow survey of 2019 recorded 53.9 inches of snow depth and a snow water equivalent of 34.43 inches, which is 202 percent of average for this location.
The Sierra snowpack is one of California’s most important water sources, with its spring and summer runoff feeding rivers and reservoirs. Mountain snowpack provides about 30 percent of the yearly fresh water supply for California.
“We not only had a lot of precipitation this winter, (but) colder temperatures as well, which caused a dense snowpack. Dense snow means there is a lot more water content in the ice than when it’s powder,” EBMUD Manager of Water Operations David Briggs said.
Although the water source provides water for the Central Valley through the Mokelumne River, it presents a serious danger for flooding in the region.
“Pardee dam is currently at 101 percent (capacity) and Camanche is at 86 percent,” EBMUD Senior Public Information Representative Andrea Pook said. “Once Pardee fills, it spills over into Camanche, and we release water into the Mokelumne.”
As the snow trickles into nearby dams and streams, EBMUD calculates the volume of water being released from the Dams into the Mokelumne River based on federal regulations as a measure of flood control.
The United States Army Corps of Engineers is the federal agency that permits the release rate of water from the dams into the rivers, Briggs said.
“We maintain water levels to confirm they adhere to comply with flood control guidelines of 5000 (cubic feet per second),” he said.
One cubic foot of water weighs 62.5 pounds, and cubic feet per second, or cfs, is the measurement used to determine the amount of water passing from any given point into a river within one second.
“We are currently at 2,900 cfs (at Camanche). We still have a lot of room and time before we get to 5000 cfs,” Briggs said.
As EBMUD releases water into the Mokelumne River, the impression that the river is rising is only temporary.
Briggs explained that through the month of June, EBMUD will release more water from the dams, but once we reach July 1 the water levels will drop to normal levels because ice melt will slow down or stop completely.
“As we go through these minor heat waves we will be releasing more, but that is common this time of year unless we are in a drought,” he said.
As water is released, recreational activity on Lake Camanche and the Mokelumne River is more risky, due to the faster water flow coming in.
“We warn about the people about the speed of the water more than anything. The temperatures don’t drop as much (during the water release), because water at the bottom of the lake is brought to the top,” Joe Waid, an engineer with the Clements Fire Department said.
The rapid water speeds have forced the closure of Stillman Magee Park, which is home to recreational water activities, in an effort to prevent any drowning at the park.
The closures are temporary, according to Waid, but are expected to open once water levels slow down.
A snow plow clears a road near Highway 395 near Mammoth Lakes on Feb. 6.