Oroville >> State and federal reservoir levels have been dropping at dramatically different rates for the last couple of months, for reasons that figure into last week’s discussions about the twin tunnels under the Sacramento-San Joaquin Delta.
Lake Oroville has released more than 968,000 acre-feet of water into the Feather River since June 1, while just over 616,000 acre-feet have flowed from Shasta Lake into the Sacramento River.
Oroville has gone from 83 percent full to 66 percent full in that time, while Shasta dipped from 86 percent full to 78 percent full. Oroville’s water level has dropped 62 feet, Shasta, just 15 feet.
Why it’s happening
What’s happening is the state is fulfilling water supply contracts, while the feds have been directed to save more water for endangered salmon, according to Kevin Wright, water services supervisor for the Department of Water Resources in Oroville.
Wright said there’s more water flowing in the Feather River now because DWR has a shorter time window to deliver it.
Due to the declining Delta smelt “it was hurry up and wait, hurry up and wait, and then suddenly there are no restrictions.”
The state had pledged 60 percent of contracted water supplies to customers of the State Water Project, and the regulations limited the time available.
“We have to move a lot of water in a short amount of time,” Wright said. “We need to get water to the people who paid for it.”
By comparison, the federal Central Valley Project only promised 5 percent of contracted water to its customers south of the delta.
Wright said the Bureau of Reclamation has been conservative about releasing water, partly because a shortage of water the last couple of years dried up of salmon eggs laid in the Sacramento River, with the endangered winter-run chinook a main concern.
“They were told, ‘you won’t do that again’,” Wright said.
Other factors figure into the flows, like maintaining water quality in the delta. Enough fresh water has to flow out to keep salt from intruding. Unless water quality standard are met in the delta, no water can be pumped, Wright said.
Perspective
While Lake Oroville is dropping, it is almost exactly twice as full as it was this time of year. The lake was at 33 percent of capacity on Aug. 1, 2015. Shasta was 44 percent full then.
And the situation locally this year is far better than elsewhere in the state. New Melones Lake on the Stanislaus River was just 24 percent full Monday. San Luis Reservoir near Los Banos is just 10 percent full.
Reach City Editor Steve Schoonover at 896-7750.
