By Jay Lund
Summary of conditions
March 2016 has been unusually wet, and quite a contrast to February. The “Godzilla” El Nino this year has been a bit “Gonzo”, but overall has brought a welcome above average precipitation for northern California, after four solid drought years. The unevenness of the precipitation is some concern, and the depth of remaining surface and subsurface storage drawdown from the drought remains sizable.
Annual precipitation and snowpack are now about average overall for California. The largest reservoirs in northern California are in good shape, with sizable, about average, snowpacks waiting to trickle down in spring. Overall, total surface storage in California is about 2.7 million acre-ft below average for this time of year (improved from an 8 maf surface storage deficit in October). Groundwater will be recharging, as it should this time of year in most places, but groundwater is likely to remain drawn down in much of the southern Central Valley.
California remains in a drought, a bit. So far, the much-hyped El Nino has brought us largely average precipitation and snowpack. A huge improvement over the last few years, but not an excuse to forget the lessons of the drought so far. And who knows what next year will bring.
Here are recent highlights, with links to the California Department of Water Resources’ California Data Exchange Center (CDEC) at http://cdec.water.ca.gov.
Reservoir and Groundwater Storage Conditions
Major reservoirs in northern California are mostly healthy this year, but substantially emptier south of the Delta.
California’s total reservoir storage remains about 2.7 maf (about 2.7 full Folsom reservoirs) less than average for this time of year. This is a nice improvement from being 8 maf below average in October. Groundwater statewide will be making some recovery but will be a long way from recovering from drought in many drier areas south of the Delta.
The drought by 2015 depleted total storage in California by about 22 maf cumulatively or nearly a year’s worth of water use in agriculture. Storage is recovering during this wet season, but still has a good bit to go, probably 12-16 maf of drought storage drawdown remains, mostly from groundwater.
Precipitation and Snowpack
Precipitation in most of California is far superior to the last four years of drought. But we have had some very dry months (February) and some very wet months (March and January). Southern parts of California, south of the Delta, have had a smaller share of relative water bounty, but are in much better shape than last year.
http://cdec.water.ca.gov/cgi-progs/products/PLOT_ESI.pdf – Sacramento Valley
http://cdec.water.ca.gov/cgi-progs/products/PLOT_FSI.pdf – San Joaquin Valley
http://cdec.water.ca.gov/cgi-progs/products/PLOT_TSI.pdf – Tulare Basin
Much better than the last four years, but still a bit of drought. A very wet March, and fairly wet December and January, has helped recover from a dry February and four years of drought. Northern California is in mostly good shape for the coming year. More southern parts of California are more stressed, but still far better off than the previous four years. Lingering drought effects will continue. A “Godzilla” El Nino is no guarantee of a drought-buster.
It is unclear if the next year will be a return to drought conditions, but the forecast for April so far seems mostly dry.
UC Davis’ drought seminar series videos are now available at: https://watershed.ucdavis.edu/education/classes/california-water-policy-seminar-series-drought
Jay Lund is Director of the UC Davis Center for Watershed Sciences and Professor of Civil and Environmental Engineering at UC Davis.
Paul Ullrich (Video): Drought in California: A climatological look at water in a semi-arid landscape. UC Davis School of Law and Center for Watershed Sciences Water Policy Seminar Series, January 13, 2016
Jay Lund (Video): Drought and Water Management in California. UC Davis School of Law and Center for Watershed Sciences Water Policy Seminar Series, January 6, 2016