-February 10,2023-
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 Users on their website. Here is what they wrote early this month. ”The first Friant Water ASO flight of the water year found there is approximately 340,000 AF 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 the DWR Bulletin 120 report on expected runoff predicted 3.26 million AF on the San Joaquin River, source of the all important Friant Kern Canal.That is much better than the 1.6 million AF annual average from the 16,000 acre basin.
Indeed this chart tells the story – there is a record amount of snow in the upper Sierra for this time of year, already 160% of April 1 average in the South and on track as the wettest year ever (if the rain keeps coming). The pictured three-region chart shows the Southern Sierra ahead of 1982/83 water year water content for the date and 201% of average for the date (Feb 8).
Flood releases drain the lake
Recognizing all that stored water up there, the thinking of water managers and the Corps of Engineers has been to dump thousands of acre feet from Terminus Dam (Lake Kaweah) since Jan 1 (see chart). Vacating the reservoir built to insure downstream floods don’t happen, the Corps took the reservoir from over 83,000AF down to 25,000AF in anticipation of a whopper of a snow melt in coming months.
Kaweah Delta Water Conservation District“s GM Mark Larsen says the releases have stopped at 25,000AF of storage as of Feb 8.
On January 10, this writer wrote “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 25,000AF with releases down the Kaweah River channels being put to beneficial use in scores of recently constructed recharge basins and about 40 such recharge basins overall that have been waiting for wet year to be put into service.
Larsen says 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 says in recent days Kaweah Water Conservation District made a deal with Kaweah region growers in the “white areas” who do not get surface water but depend only on drought-impacted groundwater.
Kaweah Delta, because flood releases require places to put that water – reached out to growers in the so-called white areas. They 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 SGMA program. That flood release program also ended this week.
Larsen says 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 277,000AF on an April-July basis, used to estimate irrigation water supply. Using either measurement “it looks very promising” says Mark.
Could be double dose
For the South Valley Rivers the Bulletin says “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.”