A disappointingly dry January is pushing California toward a remarkable third consecutive year of drought, state water managers are saying as they survey shrunken reservoir levels and vanishing mountain snowpacks.
Scientists believe the state has not suffered three consecutive drought years in nearly 400 years. They base this belief both on recorded history and data extrapolated from growth rings on ancient trees. Narrow rings, showing little growth in a particular year, indicate drought.
The current gloomy outlook arises because California’s rainy season is more than half over, but its reservoirs are not half full. Despite bountiful snow for skiers, climatic conditions are such that the state is not getting enough runoff where it is needed--in the Northern California hills that feed major reservoirs. Runoff has dipped to 47% of normal this year, managers said.
“It will take a lot of rainfall to bring us up to where we were last year, and last year was the second year of a drought,” said William J. Helms, chief of the state drought center in Sacramento.
Official drought watchers have said the state would require at least 70% of normal capacity in every major reservoir as well as an above-average snowpack before the Department of Water Resources could even consider calling an end to the drought.
Helms said there is only a 50% chance that February and March will be sufficient to obviate plans for significant mandatory rationing. Farmers already have been told to expect 40% less irrigation water this year, and urban water agencies are being urged to redouble their conservation efforts.
The Los Angeles Department of Water and Power, which has its own independent sources of water from the eastern Sierra, is in no better shape, said spokesman Jim Wickser. The snowpack on which it depends is only 70% of normal for this time of year and would need to be close to 150% of normal through March to recover.
“I think we’ll be looking for mandatory conservation in the city of Los Angeles if things do not improve,” Wickser said. Voluntary conservation programs in use now will not save enough water to make a difference, he said.
As bad as the situation is, Helms said the state’s water situation is not yet as desperate as it was during the 1976-77 drought. He said this is because several new reservoirs have been added in the last decade and water management and conservation practices have improved.
However, he cautioned that a third year of drought now could again prove a problem. Ironically, Northern California cities would be most dramatically affected because they rely much more on runoff from the Sierra Nevada.
With two months remaining in the rainy season, Helms and Libby are hopeful that the state can recoup its usual water reserves, but figures show precipitation through the end of the seven-month rainy season in April would have to be 130% of normal to do so.
Meteorologist Dave Beusterien of WeatherData Inc., which supplies forecasts to The Times, said Monday that changes in the jet stream should bring above-normal precipitation to Central and Northern California in the next two weeks, but probably not 130% of normal.
On the land feeding Lake Oroville, the largest State Water Project reservoir, only 13.46 inches of rain, about 24% less than usual, has fallen so far this season. Much of what did fall was soaked up by desiccated mountain soils before reaching the lake.
As a result, the lake, already sapped by two years of drought, now holds less than half its capacity and about 69% of its average historical volume for this time of year. Other lakes are faring even worse. Federally managed Lake Shasta, California’s largest reservoir, has only 40% of capacity, while Folsom Lake near Sacramento contains only 30%.
Reservoirs Are Crucial
These reservoirs and others in the northern third of California are critical because they represent the bulk of the state’s storage capacity of surface water. Central California has far fewer facilities to help it through the summer and Southern California has fewer still. Both regions rely on northern water sent south through managed rivers and aqueducts.
This year’s lack of runoff is no more evident than at Lake Oroville, where water operations manager Ronald M. Libby can drive his pickup across acres of dry, red clay lake bed to oversee work crews repairing floats and other gear that have been beached by the receding water.
The tree line ringing the reservoir, and demarcating the normal high-water mark, looms 150 feet above the lake level. Boat ramps barely stretch to the lake surface and several abandoned cars have been exposed on the sloping sides of the reservoir after years of quiet submersion.
Enough snow has blanketed the Sierra Nevada to delight skiers this winter, but the snowpack is proving a disappointment to water officials for a number of reasons. It is so fluffy that it has a below-average water content, and without replenishment it has slowly been shrinking--from 115% of normal at the start of the month to 90% last week.
“Each snowless day it drops another percentage point,” Helms said.
As it melts, however, it does not benefit the reservoirs.
“We have a lot of snow up there, but it’s all fallen on a sponge,” Libby said, referring to dry soils. “What little has melted so far has soaked right into the ground.”
MEASURING THE DROUGHT
Disappointing precipitation in the first half of California’s rainy season has left water levels so low at drought-starved Lake Oroville, above, that service boats are dwarfed by the exposed, sloping lake bed. Water level is 150 feet below capacity.
Water managers measure the severity of California droughts by the amount of water in remote Northern California reservoirs like Oroville. Rainfall in cities is less important because cities lack storage systems large enough to carry them through dry summers. Storage at 70% of historical average in all reservoirs is needed to avoid shortages. These storage data for selected reservoirs in California are as of Jan. 24; all figures are expressed in acre-feet, a standard water measurement equal to 325,800 gallons.
RESERVOIR MAXIMUM CURRENT YEAR AGO HIST. AVG. NAME CAPACITY STORAGE THIS DATE THIS DATE Oroville 3,538,000 1,692,000 2,613,000 2,450,000 (47.8% of capacity; 69.1% of historical average to date) Shasta 4,552,000 1,844,000 3,308,000 3,232,000 (40.5% of capacity; 57.1% of historical average to date) Folsom 1,010,000 298,000 386,000 588,000 (29.5% of capacity; 50.7% of historical average to date) Claire Engle 2,448,000 1,266,000 1,669,000 1,848,000 (51.7% of capacity; 68.5% of historical average to date)
Source: California Department of Water Resources