California has had a record-breaking water season in 2023, with the Southern Sierra Nevada snowpack currently sitting at 300% above the historical average. Due to warmer weather patterns in early March, many regions throughout the state experienced extreme flooding and record-breaking reservoir levels. But now, in mid-April, reservoir levels have dropped significantly, leaving residents wondering why. Below are some of the reservoirs that have raised levels of concern for residents in California.
Millerton Lake
If you look back at the California Department of Water Resources (CDWR) Major Water Supply Report on January 15, 2023, Millerton Lake was at 83% capacity and 143% above the historical average. Fast forward to this week, April 18, 2023, the report shows that Millerton is back down to below the historical average at 34% capacity.
Dam operators are doing this in preparation for the warmer months to come, and are releasing a steady 8,000 - 9,000 cubic feet per second into the San Joaquin River because there is enough snowpack to fill Millerton and 8 upstream reservoirs 3 times over.
The California Department of Water Resources forecast that 2.92 million acre-feet of water will flow into the San Joaquin between now and the end of July. Much of that is expected to occur in May (930,000 acre-feet) and June (1.03 million acre-feet).
Millerton and the 8 upstream reservoirs have a total storage of 1,130,788 acre-feet. That’s nearly 3 million acre-feet of water and roughly 1.1 million of storage.
Pine Flat
Similarly, if you look back at the CDWR Major Water Supply Report on March 21, 2023, Pine Flat was at 78% capacity and 154% above the historical average. Looking ahead nearly 1 month later, the report shows that Pine Flat is back down to 52% capacity and below the historical average.
Pine Flat Lake stores nearly twice as much water as Millerton and its largest forks (the Middle and South) are free-flowing. When the snow melts at the upper elevations of Kings Canyon National Park, Pine Flat can fill in a hurry.
The Kings River is expected to surge in May (990,000 acre-feet) and peak in June (1.11 million acre-feet) and does not have a natural outlet, making it partially responsible for Tulare Lake’s resurgence in Kings County. Flows into Tulare Lake are between 1,500 and 2,000 cfs and could last until summer.
Tulare Lake (which is fed by several other rivers and creeks) has surpassed 100 square miles, by several estimates. How large it gets depends on how gradually the snow melts.
Trinity Lake
Lastly, when you look at the recent months levels of Trinity Dam, the story is a little different. Trinity has remained consistent with an average storage for the water year at 33%, leaving county residents concerned.
Water releases are made each day from Trinity Reservoir and released through the Trinity power plant into the Trinity River, in order to produce hydropower. These releases are typically not visible to the public.
The Bureau of Reclamation has been waiting for parts to repair the tube that supplies water to the power plant. As a result of the construction activities, water releases are currently bypassing the power plant and are directly released from the dam’s auxiliary valve, which is visible to the public.
“There is releases being made but, absolutely, no extra releases are being made because of the construction project, the ongoing construction project that we are gonna wrap up here in a couple weeks, were just making normal releases, the lake is building up but not to where we would like to see it,” said Area Manager Donald Bader in a statement to ABC 7 KRCR.
Trinity “is heavily dependent on snowpack; versus Shasta, which is mostly dependent on rainfall to fill,” Mary Lee Knecht, Bureau of Reclamation Region 10 public affairs officer, wrote in an email to the Chronicle.
Much of the snowfall may not melt and flow into the reservoir until late spring or summer, according to the Trinity River Restoration Program.
