Final measurement of snow in Sierra shows water-rich snowpack at 190% of normal

Monday was the final manual snow survey at Phillips Station in the Sierra Nevada, and the snowpack is still measured at a healthy 190 percent of the May 1 long-term average of Snow Water Equivalent (SWE) which is 14.6 inches. Today's measurement was 27.8 inches.

The survey was conducted by the Department of Water Resources (DWR).

Electronic measurements statewide show a snowpack of 42.5 inches which is 196 percent of average. The SWE of the northern Sierra snowpack is 39.9 inches (199 percent of average); the central and southern Sierra readings are 47.1 inches (202 percent of average) and 37.6 inches (180 percent of average), respectively.

Hydrologists use these figures to forecast the spring and summer snowmelt runoff into rivers and reservoirs. The melting snow supplies approximately one-third of the water used by Californians.

"California’s cities and farms can expect good water supplies this summer,” said DWR Acting Director Bill Croyle. “But this ample snowpack should not wash away memories of the intense drought of 2012-2016. California’s precipitation is the most variable in the nation, and we cannot afford to stop conserving water.”

Snowpack water content is measured manually on or near the first of the month from
January to May. The Phillips snow course, near the intersection of Highway 50 and
Sierra-at-Tahoe Road, is one of hundreds surveyed manually throughout the winter.
Manual measurements augment the electronic readings from about 100 sensors in the
state’s mountains that provide a current snapshot of the snowpack’s water content.
The first of April is normally when snowpack water content is at its peak.

Frank Gehrke, chief of the California Cooperative Snow Surveys Program, conducted
DWR’s survey today at Phillips near Sierra-at-Tahoe and said of his findings, 2017 has been “an extremely good year in terms of the snowpack.”

Gehrke said the snowpack is encouraging in terms of surface water supplies. “The thing we’re looking out for is primarily the southern Sierra, where we have full reservoirs and in some cases a huge snowpack,” he said. “We want to make sure that we prudently manage that so we don’t cause any downstream issues.”

California's reservoirs are fed both by rain and snowpack runoff. A majority of the state's major reservoirs are above normal storage levels for today’s date. Lake Oroville in Butte County, the State Water Project's (SWP) principal reservoir, is 91 percent of average for the date (74 percent of its 3.5-million acre-foot capacity). Shasta Lake north of Redding, the federal Central Valley Project's largest reservoir with a capacity of 4.5 million acrefeet, is at 109 percent of average (94 percent of capacity).

Earlier this month, DWR increased its estimate of this year’s SWP supply to 100 percent of requests for contractors north of the Sacramento-San Joaquin Delta and 85 percent of requests for other contractors, the highest since the 100-percent allocation in 2006.