WANING WATER: Tahoe, reservoirs forecast to drop sharply as summer progresses
A second slow winter in a row could mean water stops spilling over the dam at Lake Tahoe, cutting off flow at the top of the Truckee River.
Despite abundant snow early in the winter season, a uncharacteristically dry spring has meant runoff hasn’t kept up with evaporation, dropping Lake Tahoe in months that traditionally refill the lake.
“The lake may come up a few hundredths of an inch, but this looks like it’s about as high as it’s going to get,” said Chief Hydrologist Chad Blanchard with the U.S. District Court Water Masters Office.
The current lake level for Tahoe, as of Monday, is 6225.48 feet, Blanchard said.
“We’ve had terrible inflow ” almost as bad as last year, and last year the snowpack was much less,” Blanchard said.
Because almost all precipitation fell as snow, the soil never saturated, and snowmelt went into the ground rather than running into Lake Tahoe and other reservoirs, Blanchard said.
Coupled with high winds that evaporated both the lake and snow, this springs goes into the record books as the worst for lake rise in 108 years, along with 1977, Blanchard said.
“The rise into Tahoe in March and April was actually negative ” evaporation was higher than in-flow,” he said.
This could mean by the end of the year Lake Tahoe could drop another 2.5 feet to the natural rim at 6223 feet in elevation, stopping flow over the dam, Blanchard said.
“The river would go dry until it gets further downstream, but by that time hopefully we’ll get new moisture,” Blanchard said.
Tributaries and reservoirs further downstream could still maintain the minimum “Floriston Rate” of flow, however, and the Water Masters Office would draw heavily on Boca to maintain water supply for Reno and Sparks, he said.
“Boca could get very low, but should be at a pretty good level most of the summer,” he said.
But Lake Tahoe dropping below its natural rim isn’t uncommon, Blanchard said, listing 2003, 2004 and 2005 as years where the rim was reached.
He said he expects to be able to get through this year on the water available, but is hoping for a better winter for 2008-09.
“If we get another dry year we are going to have a problem,” Blanchard said.
The North Tahoe Public Utility District won’t have any problems drawing water from the lake, said Lee Schegg, public works director for the district, as they use submersible pumps well below lake levels.
“Our supply is un-impacted by the lack of precipitation,” Schegg said.
But boat launches will be another story, he said.
“The Tahoe Vista recreation area definitely shuts down within one foot of the natural rim,” Schegg said. “We’re already going to restrict to shallow-draft.”
Elsewhere, Prosser reservoir has pretty much peaked out at 21,207 acre feet, compared to its 29,840 acre feet total, and will be drawn down to 9,800 acre feet by the end of the year, Blanchard said.
In Truckee, however, water supplies drawing entirely on underground aquifers look no worse than normal years, said Ed Taylor, water utility director for the Truckee Donner Public Utility District.
“Our water supply is in great condition,” Taylor said. “Our wells have been consistent year after year.”
The utility district draws its water from wells about 1,100 feet deep in the Martis Valley, Taylor said.
“The Martis Valley basin is like a big bowl that fills and then overflows into the Truckee River, so we get first shot at the water,” Taylor said.
Even though it’s much smaller than Truckee’s, Squaw Valley’s aquifer has also fully recharged this year, said Rick Lierman, general manager of the Squaw Valley Public Service District.
“We plan for two consecutive drought years in a row,” Lierman said. “So we’re hoping for a better winter this coming year.”
Likewise Tahoe City Public Utility District’s ground water appears to be in good shape, said Cindy Gustafson, general manager for the district.