Supply Outlook Improves, but State Remains in Drought
The California Department of Water Resources (DWR) increased its water allocations estimated delivery for most recipients to 30 percent of requests for the calendar year. However, recipients are being warned that extended dry weather could force an allocation reduction.
“The increase, although good news, does not mean the drought is ending,” said DWR Director Mark Cowin. “After more than four dry years, we still have a critical water shortage. We need a lot more wet weather this winter to take the edge off drought. Using water carefully and sparingly is still the quickest, most effective way to stretch supplies.”
The announcement is the second incremental increase in the State Water Project (SWP) allocation since an initial allocation of 10 percent was announced in December. An increase to 15 percent was announced on January 26, after storms began to build the Sierra Nevada snowpack and bring significant rainfall to the drought-parched state.
The 29 public agencies that receive SWP water (State Water Project Contractors) requested 4,172,786 acre-feet of water for 2016. With today’s allocation increase, they will receive 1,268,724 acre-feet. The 30 percent allocation announced today may be increased if storms bring more rain and snow.
A remarkably dry February limited today’s allocation increase – a stark reminder of how quickly California can turn from wet to dry.
Outdated water delivery infrastructure in the Sacramento-San Joaquin Delta also affected today’s allocation increase. SWP pumping in the Delta has been limited this winter in order to minimize harm to native fish species. DWR estimates that 458,000 acre-feet of water – enough to supply 3.4 million people for a year – could have been captured if the new intakes, tunnels, and operating criteria proposed by California WaterFix had been in place. That project proposal is now undergoing environmental review.
For the last two years, federal and state fish and wildlife agencies have been working together closely as a Real-Time Drought Operations Management Team to capture water supply in the Delta without unreasonably affecting threatened and endangered fish species. That team works to balance multiple demands in the Delta while managing water project pumping infrastructure that pulls south Delta channels – and native fish – in unnatural directions. California WaterFix would minimize these harmful “reverse flows.”
There is no exact formula for ending the drought and conditions vary region by region, but a rough guidepost is that approximately 150 percent of average winter precipitation – rain and snow – would significantly ease statewide conditions, with the major exception of groundwater depletion.
The severe drought that began in 2012 has diminished water supplies to all sectors. California communities have been ordered to reduce overall water use by an average of 25 percent compared to 2013 levels. Some streams have dried up entirely, and others have gone slack and warm enough to threaten native fish populations. Flow requirements for environmental purposes were reduced in 2014 and 2015 by state regulators struggling to balance competing demands for water. Water project deliveries to farmers have been reduced drastically, with some getting no deliveries for two consecutive years. No crops were planted on more than half a million acre-feet of California farmland last year.
Collectively, the SWP Contractors serve approximately 25 million Californians and just under a million acres of irrigated farmland. The project provides the same allocation percentages to urban and agricultural water districts.
It is important to note that nearly all areas served by the SWP also have other sources of water, among them streams, groundwater and local reservoirs.
Key reservoirs are rising from early winter storms, but most remain low.
Lake Oroville in Butte County, the State Water Project’s principal reservoir, early this morning was holding 1,808,410 acre-feet, 51 percent of its 3.5 million acre-foot capacity and ¬¬74 percent of its historical average for the date. Shasta Lake north of Redding, California’s and the federal Central Valley Project’s (CVP) largest reservoir, was holding 2,690,554 acre-feet, 59 percent of its 4.5 million acre-foot capacity and 82 percent of its historical average. San Luis Reservoir, a critical south-of-Delta pool for both the SWP and CVP, reflects the same trend of lower reservoir storage this year. San Luis was holding 854,623 acre-feet, 42 percent of its 2 million acre-foot capacity and 50 percent of normal for the date.
Folsom Lake, a CVP reservoir near Sacramento, has risen to 64 percent of its 977,000 acre-foot capacity, 117 percent of its historic average for the date. Folsom fills more rapidly than many other reservoirs due to its relatively small size compared with its huge watershed.
Groundwater aquifers recharge much more slowly than surface reservoirs, with many in the Central Valley sinking toward record levels.
Last year’s (2015) 20 percent allocation was the second lowest since 1991, when agricultural customers of the SWP got a zero allocation and municipal customers received 30 percent of requests. In 2014, SWP deliveries were five percent of requested amounts for all customers.
The last 100 percent allocation – difficult to achieve even in wet years largely because of Delta pumping restrictions to protect threatened and endangered fish species – was in 2006. SWP allocations in recent years:
•2015 – 20 percent
•2014 – 5 percent
•2013 – 35 percent
•2012 – 65 percent
•2011 – 80 percent
•2010 – 50 percent
•2009 – 40 percent
•2008 – 35 percent
•2007 – 60 percent
•2006 – 100 percent
Governor Edmund G. Brown Jr. declared a drought state of emergency on January 17, 2014 and followed up with statewide water conservation mandates. Since then, the state has been swept by drought-fueled forest fires, in addition to vast tracts of farmland being fallowed and some communities left scrambling for drinking water.
Long-range weather forecasts are uncertain, and there is no way to know if this winter will deeply dent the state’s historic drought. DWR’s California Data Exchange Center (CDEC) Web sites show current water conditions at the state’s reservoirs and weather stations.
Reservoirs: http://cdec.water.ca.gov/cdecapp/resapp/getResGraphsMain.action
Precipitation: http://cdec.water.ca.gov/snow_rain.html
Snow: http://cdec.water.ca.gov/cdecapp/snowapp/sweq.action