RENO - As northern Nevada welcomed the first full day of summer Monday, Lake Tahoe was about 2 feet lower than a year ago, and water officials predicted it could drop below its rim by fall because of ongoing drought.
Lake Tahoe's average level at the end of June, based on 75 years of records, is 6,226.78 feet, according to Federal Water Master Garry Stone.
On Monday, the lake's level stood at 6,224.27 feet.
"We're 2 feet down below where we'd be at the end of June," Stone said.
That drop, he said, equates to about 240,000 acre feet of water. An acre foot is enough water for a family of four for a year.
Lake Tahoe last inched below its rim of 6,223 feet on Nov. 20, 2003, but came back up Dec. 7, said Gary Barbato, a hydrologist with the National Weather Service in Reno.
"This year it's quite a bit lower, so it's going to go down even sooner," Barbato said.
Stone, who is in charge of managing the Truckee River that is fed by Lake Tahoe, said his office will be able to meet mandated flows known as the Floriston rate through about mid-September.
"We are down to the Floriston rate probably earlier than we normally would on an average year," Stone said.
As of Monday, that rate was 500 cubic feet per second, with an additional 60 cfs released for fish at Pyramid Lake, he said.
By the time the river gets to the Reno-Sparks area, the flow is noticeably less because of upstream diversions, Stone said.
The river's flow of 323 cubic feet per second in Reno dropped to 289 by the time it reached Sparks, he said.
A disappointing winter and a warm spring produced an early runoff that has rivers running at levels typically seen later in the summer, officials said.
Barbato said the runoff on the Truckee River from May through the end of July is predicted to be about 48 percent of average - or 93,000 acre-feet, compared with 193,00 acre-feet during an average year.
"That's usually the biggest slug for snowmelt," he said of the late spring and early summer months.
"It's just been a pretty lackluster year to say the least," Barbato said. "It's been pretty dry.
"We can just look forward to next year, hopefully," he said.
The National Oceanic and Atmospheric Administration's Climate Prediction Center forecasts the drought that has gripped much of the West for five years will persist or intensify this summer.
The last time the Lake Tahoe Basin had an above average winter was in 1999, Barbato said.
That year precipitation in the Truckee River watershed also was slightly above normal at 102 percent.
It's been downhill since then, with precipitation at Tahoe registering at 76 percent as of June 1 for the water year that ends September 30.
Precipitation amounts this year are even lower for western Nevada's two other major rivers, reaching only 70 percent along the Carson River watershed and 75 percent along the Walker River.