Surprise! Friant’s Supply Is Up
Higher Than Expected Runoff Permits Class 1 Declaration Boost to 55%
There is no denying that the current water year’s conditions have been extremely dry but nature has provided the San Joaquin River with a welcomed supply surprise. As a result, Friant Division users of Central Valley Project Class 1 water have received a pair of water supply increases during June’s first two weeks.
The U.S. Bureau of Reclamation on June 13 increased the Class 1 supply to 55% of contract amounts, or 440,000 acre-feet. That action came just eight days after the Bureau hiked the Class 1 allocation to 50% (400,000 acre-feet) from 45%, a point reached after an earlier series of supply reductions. The 45% declaration would have provided Class 1 users with 360,000 acre-feet.
No Class 2 water is available for the second straight year. The 1.4 million acre-feet of Class 2 water is made available only after Reclamation determines a full Class 1 supply of 800,000 acre-feet can be delivered.
The latest increases are based upon conservative runoff predictions and scheduled River Restoration Program releases. They also reflect daily full natural flow amounts that until June 11 had stayed surprisingly high, above 2,000 cubic feet per second, over the previous several weeks.
The June 12 calculated natural flow (as it would have occurred at Friant if there were no dams) dipped to 1,891 c.f.s. Natural flows on the neighboring Kings and Merced rivers dropped fairly steadily during the comparable period.
Runoff forecasts have decreased on San Joaquin Valley river systems in every week but one since the season’s predictions began February 1, reflecting record dry conditions that have existed since New Year’s. That’s why the San Joaquin’s extraordinary natural flows have been so unexpected.
“It’s weird,” Reclamation’s Central California Area Office Manager, Michael Jackson, said at a June 7 Friant Water Authority Advisory Committee meeting in Visalia. “I don’t know where this water is coming from.” There have been some locally heavy thunderstorms in the mountains but little more. The Bureau’s official announcement of the latest increase cited “better than expected hydrologic conditions through the first 12 days of June.”
Precipitation in the upper San Joaquin River watershed, as measured at Huntington Lake in northeastern Fresno County, is about 20.5 inches, some 49% of average for mid June, the Bureau reported.
Accumulated natural river flow to date for Water Year 2013 for the upper San Joaquin Basin is about 766,000 acre-feet, which 57% of the historical average for this date, and about 43% of the total water year average of 1.8 million acre-feet.
With low demand based in large part on the lack of Friant’s Central Valley Project supply, Millerton Lake storage has continued to increase.
As of June 12, Millerton Lake held 411,881 acre-feet, 79.1% of capacity, and was still rising slowly.
The reservoir is expected to drop quickly as more Friant Division districts begin or step up their water runs.
Reclamation has indicated that even with the higher allocation, Millerton Lake storage will remain above the lake’s “dead storage” pool storage level of 135,000 acre-feet. Below that point, water could no longer be diverted into the Madera or Friant-Kern canals.