The Drought Goes On
Water Year Is State’s Third Driest
There is little reason for new year’s cheer as the state’s third driest water year ever has ended only to set California’s fourth consecutive year of drought on its dry way.
For the San Joaquin River, calculated full natural flow (as runoff would have occurred if there were no dams) ended up the 2013-14 water year that concluded September 30 at 509,579 acre-feet, just under 30% of the annual average.
It was the third smallest San Joaquin River natural flow ever recorded, trailing only 1976-77 and 1923-24.
Minimized by far-below-average amounts of melting snow during the spring, the San Joaquin’s deficient runoff contributed to the Friant Division’s first-ever Zero water allocation.
Even greater causes were U.S. Bureau of Reclamation water management actions, influenced in part by fish agency and State Water Board decisions, that prevented the San Joaquin’s historic water rights holders, the Exchange Contractors, from receiving their full dry-year entitlement of substitute water supply from the Delta.
As a result, the Bureau of Reclamation released more than 200,000 acre-feet of water from Millerton Lake and down the river before releases ended October 1.
A 52-day early winter dry spell in which no precipitation was recorded sealed Central California’s dry 2013-14 fate.
For several weeks last winter, the San Joaquin’s precipitation totals were trailing those in 1924. Only a few light to moderate spring storms and scattered spring thunderstorm downpours kept 2013-14 from being even a worse calamity.
WELL BELOW NORMAL
Within the broader San Joaquin River basin, the broadly-indicative precipitation index registered average precipitation of 20.4 inches, exactly half of normal and more than 6 inches less than in 2012-13. Only the 1923-24 water year’s 14.8 inches and the 1976-77 index average of 15.4 inches were historically drier. The index covers five key locations (including Huntington Lake and North Fork in the San Joaquin watershed).
A year ago, the 2012-13 water year ended with the San Joaquin River’s natural runoff yielding 46% of average, 856,626 acre-feet, slightly better than year-before totals. Those figures in retrospect look mighty good in comparison with the year just experienced.
Light late September rain that fell in the watershed and some valley locations did nothing to alleviate the dry conditions. No rain at all has fallen since the 2014-15 water year began October 1. The Sierra Nevada is without any snow cover.
Water storage figures are grim and will only get worse if conditions remain dry. Millerton Lake storage is down to 177,716 acre-feet (34% of capacity) and is expected to eventually closer to the reservoir’s “dead storage” pool of 135,000 acre-feet, below which water cannot be released into the Friant-Kern or Madera canals.
Upstream, storage in Southern California Edison Company’s hydroelectric reservoirs is only 25% of capacity. Statewide, major reservoirs collectively hold less than 55% of average storage, or about 33% of capacity.