Water officials: Wet November, December does not guarantee wet winter
January 16, 2013
California is thirsty.
From the sprawl of Los Angeles to the comparatively small agricultural villages that dot the Golden State’s Central Valley, most of the 37.5 million people that populate the state rely on the rivers that flow from the Sierra Nevada down the western slope toward the Pacific Ocean.
Locally, the Nevada Irrigation District supplies more than 25,000 residences, businesses and farms with water collected from mountain snow pack and stored in a network of 10 reservoirs.
Officials at the public agency are particularly keen on monitoring the annual construction of snow pack as it directly impacts its ability to deliver waters to its diverse customer base, said Assistant General Manager Tim Crough. NID does not conduct snow pack surveys until Feb. 1, but early indicators are positive.
“The real question is what will happen from January through mid-March. Will it put us back closer to normal or below normal? We still have a lot of uncertainty left in the winter. That will determine the final outcome.”
Nicholas Markevich, PG&E hydrologist
“We’re in good shape,” Crough said.
Precipitation totals at Bowman Lake, where NID has a measuring station, come in at about 42 inches, which is 148 percent of average, Crough said. Reservoir storage levels show NID has 223,000 acre feet of storage, which is the “highest in a 42-year average,” Crough said.
Despite the fortunate start to the water year, Crough said his agency must always prepare for the possibility of extended periods of dry weather.
California’s Department of Water Resources shares the same philosophy, as it has already conducted its first snow pack survey of the water year in January, and yielded positive results.
“We are off to a good water supply start for the new year, but we have to remember that we have seen wet conditions suddenly turn dry more than once,” said DWR spokesman Ted Thomas. “We know from experience that California is a drought-prone state, and that we must always practice conservation.”
Electronic readings indicate the water content in the northern mountains is 133 percent of normal for the date and 50 percent of the April 1 seasonal average, according to a release issued by Thomas. Electronic readings for the central Sierra also show 133 percent of normal for the date and half the April 1 average. The numbers for the southern Sierra are 131 percent of average for the date and 44 percent of the April 1 average.
DWR currently estimates that it will be able to deliver 40 percent of the slightly more than 4 million acre-feet of State Water Project water requested for this calendar year by the 29 public agencies that supply more than 25 million Californians and nearly a million acres of irrigated farmland, Thomas said. The delivery estimate is expected to increase as more winter storms develop.
The final allocation of State Water Project water in calendar year 2012 was 65 percent of requested deliveries. The allocation was 80 percent in 2011, 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 restrictions on Delta export pumping to protect sensitive fish species – was in 2006.
In addition to above average water content in the snow pack, early storms this season have replenished California’s reservoirs.
Lake Oroville in Butte County, the State Water Project’s principal reservoir with a capacity of 3.5 million acre-feet, is at 71 percent of capacity, 113 percent of average for the date, Thomas said. Shasta Lake north of Redding, the federal Central Valley Project’s principal storage reservoir with a capacity of 4.5 million acre-feet, today is at 73 percent of capacity, 115 percent of normal for the date.
An acre-foot is equal to 325,851 gallons, enough to cover one acre to a depth of one foot.
The State Water Project is the largest multipurpose state-managed water project in the United States, according to the DWR.
Pacific Gas & Electric also relies on snow pack to supply its extensive watershed network.
PG&E Hydrologist Nicholas Markevich also acknowledged the ideal start to the winter season, but also approached the coming months with a cautious optimism.
“The real question is what will happen from January through mid-March,” Markevich said. “Will it put us back closer to normal or below normal? We still have a lot of uncertainty left in the winter. That will determine the final outcome.”
PG&E manages the largest investor-owned hydroelectric system in the United States. The force of falling water generates hydroelectricity by falling through large pipes to turbines that spin generators. The hydroelectric system is constructed along 16 river basins stretching nearly 500 miles from Redding in the north to Bakersfield in the south. The water is derived from more than 100 reservoirs located predominantly in the higher elevations of the Sierra.
The company has established 68 powerhouses with a total generating capacity of 3,896 megawatts — enough power to serve about 4 million houses, the PG&E website states.
To contact Staff Writer Matthew Renda, email email@example.com or call (530) 477-4239.