May Be Reduced to Meet Critical Health and Safety Needs
December 1, 2014 - SACRAMENTO – The Department of Water Resources (DWR) today announced an initial allocation of 10 percent for the customers of the State Water Project. Depending upon the volume of rain and snow that reaches California this winter that initial allocation may be increased. Should dry conditions return, DWR may reallocate State Water Project supplies to meet critical human health and safety needs.
Improved precipitation forecasts this week allow DWR to set the initial allocation for 2015 at 10 percent, up from the five percent allocation SWP customers got this year. The level of Lake Oroville – the keystone reservoir of the SWP system and a source of water for 25 million Californians – is rising due to recent storms, after approaching its lowest level ever last month. But the state’s major reservoirs, including Oroville, are too depleted to be filled by a typical winter storm. DWR experts estimate that it will take roughly 150 percent of average precipitation for California to recover from drought.
“Storms in the extended forecast give us hope that we will return this winter to normal or above-normal precipitation levels after three years of drought,” said DWR Director Mark Cowin. “But we must be cautious and preserve adequate storage in reservoirs should conditions turn dry again.”
The 29 public water agencies that receive SWP water (State Water Project Contractors) requested 4,172,686 acre-feet of water for 2015. Under today’s initial allocation, they will receive 418,520 acre-feet. For most agencies, that amounts to 10 percent of the supplies for which they contract with DWR.
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. Also, the State Water Project Contractors will have access to any water they have left in storage from previous allocations. DWR today approved requests for delivery in 2015 167,465 acre-feet of carryover water from previous years.
DWR is hopeful that today’s SWP allocation, made before the wettest months, will increase as storms bring rain and snow to the state. If severely dry conditions develop, the allocation may be reduced. Under extreme drought conditions, the Department may re-allocate supplies based on human health and safety requirements.
On average, half of California’s precipitation occurs December through February, and three quarters from November through March.
“We will still need to conserve even when we see storms develop,” said Cowin. “It will take more than a normal winter to make up for three consecutive dry years, and using less water in our homes will keep more in our critically low reservoirs.”
As the drought pushed into its third year, DWR on January 31 dropped its initial water allocation (percentage of water requested) for calendar year 2014 from five percent to its first ever zero allocation for all SWP contractors. Storms in February and March boosted the allocation back up to five percent, making a little more than 200,000 acre-feet available to the 29 contractors, who collectively had requested slightly more than four million acrefeet. An acre-foot generally is described as enough water to supply a family of four for a year, or to cover one acre of land with one foot of water.
The only previous zero allocation in the 54-year history of the SWP was for agriculture in 1991, but cities and others that year received 30 percent of requested amounts.
This year’s five percent allocation was the lowest final calendar year allocation in SWP history as a sparse mountain snowpack melted early and rainfall was near record lows in most parts of the state.
The final SWP allocation for calendar year 2013 was 35 percent of requested water amounts. In 2012, the final allocation was 65 percent. It was 80 percent in 2011, up dramatically from an initial allocation of 25 percent. The final allocation was 50 percent in 2010, 40 percent in 2009, 35 percent in 2008 and 60 percent in 2007. The last 100 percent allocation – difficult to achieve even in wet years because of Delta pumping restrictions to protect threatened and endangered fish species – was in 2006.
California’s Water Year 2014 – overlapping with California’s driest calendar year of 2013 ended on September 30 as the third driest in 119 years of record, based on statewide precipitation.
As the Water Year (October 1-September 30) ended, the state’s reservoirs tracked by DWR collectively held only 60 percent of average storage for the date, or 41 percent of capacity. Cumulative reservoir storage on the same date in the deep drought year of 1977 was five million acre-feet less, but California had 16 million fewer people in 1977.
Lake Oroville in Butte County, the SWP’s principal reservoir, is at 26 percent of its 3.5 million acre-foot capacity (43 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, is at 23 percent of its 4.5 million acre-foot capacity (39 percent of its historical average for this time of year. San Luis Reservoir, a critical south-of-Delta pool for both the SWP and CVP, is at 24 percent of its 2 million acre-foot capacity (40 percent of average for the date).
In January, normally California’s wettest month, Governor Edmund G. Brown Jr. declared a drought state of emergency and followed up with statewide water conservation goals. Since then, the state has been swept by drought-fueled forest fires, vast tracts of farmland have been fallowed and some communities have been left scrambling for drinking water.
Long-range weather forecasts being uncertain, there is no way to tell if this winter will alleviate or deepen the drought, leaving conservation – the wise, sparing use of water – as our most reliable drought management tool.
