by Jay Lund
Summary of conditions
January 2016 has been much wetter than the previous Januaries during this drought. Precipitation is modestly above average, as is snowpack, and climatic conditions remain promising. The largest reservoirs are mostly fuller than a year ago, although not nearly to average conditions for this time of year. Groundwater is likely to be recharging, as it should this time of year in most places, but we still sit atop a large hole.
California remains in a drought. Precipitation and snowpack are now mostly above average for this time of the water year (the 2016 Water Year began October 1, 2015). So far, El Nino is delivering a somewhat above normal water year. But, overall 2016 drought conditions are likely to remain unclear until March.
The California Department of Water Resources’ California Data Exchange Center (CDEC) does a great job assembling data that give insights on water conditions. They update this every day at http://cdec.water.ca.gov.
Here are some recent highlights, with links.
Reservoir and Groundwater Storage Conditions
Most major reservoirs in California have more storage that at this time last year, but still have only about 60% of historical average for this time of year. Folsom Lake is now at 100% of average for this time of year, rising from a record-low level in November. But California’s reservoir storage remains about 7 maf (about 7 full Folsom reservoirs) less than average for this time of year.
Groundwater statewide is harder to assess, but is doubtless making some recovery from last year’s levels. It still has a long way to recover from the drought in many places.
The drought so far has depleted total storage in California by about 22 maf cumulatively or nearly a year’s worth of water use in agriculture. Soil moisture conditions were also unusually dry following 2015, diverting and delaying some runoff from early storms.
Precipitation and Snowpack
December and January storms have helped, with precipitation and snowpack mostly a bit above average for this time of year. We seem to have overcome the Curse of Zero Januaries; January precipitations for the last three years was nearly zero. This January precipitation in the Northern Sierras is above average and exceeds the sum of all January precipitation for the last five years!
Snowpack in California is mostly above average for this time of year and already greatly exceeds last year’s snow accumulations. There is a ski season.
Is it El Nino yet? Apparently, yes. But it is giving us slightly better than average conditions, which so far are much better than the last four years. No major floods yet. So far, the forecast for February looks good.
- 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
Steady, above average precipitation and a decent snowpack, so far. Much better than the last four years. Let’s hope it continues, but remain prepared for another drought year, or at least lingering drought effects even if conditions are modestly wet this year.
Wonks might be interested in UC Davis’ ongoing seminar series on drought impacts and policy (most Mondays at 4pm on the UC Davis campus). The public is welcome and videos are posted some days after each talk. Details at: https://watershed.ucdavis.edu/education/classes/california-water-policy-seminar-series-drought This Monday we’ll hear from Peter Moyle (UC Davis) and Jay Ziegler (TNC) on ecosystem impacts and management during the current drought.
Swain, D., “Enhanced El Niño storm track has finally emerged; Active pattern likely throughout California next 2-3 months”, California Weather Blog, January 17, 2016
Comparing to last year at this time, February 2015: http://californiawaterblog.com/2015/02/04/rain-or-shine-california-drought-still-kicking/
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 11, 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 4, 2016
Unimpaired flow for water year 2015: http://cdec.water.ca.gov/cgi-progs/stages/FNFSUM