Kaweah Lake drained to make room for record snowpack

TULARE COUNTY – Just as fast as atmospheric rivers filled Lake Kaweah, the reservoir drained most of that water downstream to make way for what could be a record snowpack.

In the last month, the Army Corps of Engineers have drained thousands of acre feet from Terminus Dam since Jan. 1  (see chart). The Corps of Engineers took the lake from over 83,000 acre feet (AF) down to 25,000 AF in anticipation of a wave of snow melt running down the mountain in the coming months.

On Jan. 14, The Sun-Gazette reported that the “Kaweah Lake was 412% of average with releases  beginning downstream to insure there is enough room for a big snowmelt coming this spring, according to Kaweah watermaster Mark Larsen. The reservoir water supply chart had an arrow pointing straight-up over the past month with the near empty lake going from just 10,000 acre feet Nov. 1 to 80,000 acre feet today. That’s nearly half of the lake’s 185,000 acre feet capacity.”

Now it’s down to 25,000 AF with releases down the Kaweah River channels being put to beneficial use in recently constructed recharge basins and about 40 previously constructed basins that have been waiting for wet year to be put into service. One of the biggest basins is Hannah Ranch that is under construction still and won’t be ready until next year. Then there is Paregien Basin, already in service with a plan to triple its capacity funded by a grant.

Larsen said the district reached out to Kaweah region growers in the “white areas,” those places that do net have access to surface water and depend solely on drought-impacted groundwater, to find a place to put the excess water. The growers agreed to take some and use it to recharge their groundwater, a move not only in their best interest but a decision that should put them in better standing with the state under the landmark legislation known as the Sustainable Groundwater Management Act (SGMA). Passed in 2014, the law requires water agencies in each watershed to implement policies to sustain groundwater levels going forward. 

Larsen said the region has seen a relatively dry February so far, after a wet January, but is encouraged by the prediction that runoff could be around 163% of average on the Kaweah. The average annual runoff is about 440,000 acre feet for the water year but 277,000 acre feet on an April-July basis, used to estimate irrigation water supply. Using either measurement “looks very promising,” Larsen said.

Snowpack ahead of wettest year ever

Aerial measurement of the snow water content in the upper San Joaquin River watershed is finding lots more water up there than estimated, says Friant Water Authority on its website. Here is what they wrote earlier this month: “The first Friant Water [Airborne Snow Observatory] flight of the water year found there is approximately 340,000 [acre feet] more snow water content than previously estimated and the water year appears to be near the top 3-5 years for February 1st snowpack in SJR history (dating back to the 1920s).”

This week DWR’s Bulletin 120 report on expected runoff predicted 3.26 million acre feet (AF) on the San Joaquin River, which feeds into the all important Friant-Kern Canal. That is much better than the annual average of 1.6 million acre feet for the 16,000-acre basin.

In other words, there is a record amount of snow in the upper Sierra for this time of year, already 160% of average for April 1 in the lower Sierra, and on track as the wettest year ever … if the rain keeps coming. The three-region chart shows the Southern Sierra ahead of the 1982/83 water year for Feb. 8 and 201% of average for the date. 

That could mean a double dose of surface water for the region. DWR’s Bulletin 120 also reported the following for the entire basin: “For the Tulare Lake Basin (Kings River, Kaweah River, Tule River, and Kern River), the accumulated unimpaired runoff of 782,000 AF is 215% of average.”