With every little bit counting, the results of the Feb. 27 snow survey were better than last month’s, but still way below normal.
According to a press release from the Department of Water Resources, “On Tuesday, before the current storm system reached the area, water content in the statewide snowpack was 22 percent of normal for the date and only 19 percent of the average reading in early April when snow begins to melt into streams and reservoirs. These readings were just above the 1991 record lows of 18 percent for the date and 15 percent of the April 1 average.
“Manual and electronic readings today record the snowpack’s statewide water content just slightly improved at 24 percent of average for the date, still far below normal but with more snow expected. That is 21 percent of the average April 1 reading.
“Electronic readings indicate that water content in the northern mountains is 15 percent of normal for the date and 13 percent of the April 1 average. Electronic readings in the central Sierra show 32 percent of normal for the date and 28 percent of the April 1 average. The numbers for the southern Sierra are 24 percent of average for the date and 20 percent of the April 1 average.”
At Phillips Station, one of the locations where the snowpack is measured manually, Frank Gehrke, chief of the California Cooperative Snow Survey for the California Department of Water Resources, found an average of 25.7 inches of snow with a water content of 8.1 percent which is 33 percent of the long-term average.
That was a big improvement over last month when the site averaged 12.5 inches of snow with a water content of 1.5 percent, which was only 8 percent of the long-term average.
Gehrke said while the results are better, they don’t bode well for our runoff next spring and summer. “Our water content is only 8.1 percent and it should be three times that amount,” he said. “It’s a reflection that the storms coming through are fairly modest ones and once they leave, the high-pressure ridge sets in again. This helps but doesn’t materially change the outcome for this summer. It gives the watershed a little bit of moisture as the storms are bringing 2-3 inches … but we need 15 to 20 and that’s just not in the cards.”
Gehrke went on to say that even if we received 20 inches of moisture in March, we would still be below average because reservoir storage is so low. “The soils are very dry so a lot of this snow that would normally run off is going down to replace soil moisture. It takes about 20 inches of water content to replenish the soil moisture after a season in the Sierra. Until that soil moisture deficit is replaced, your runoff from a given amount of snowpack is reduced,” he said.
“A compounding problem is where you get sublimation because the snowpack evaporates so there is loss there as well,” he added. “In 1991, we had a similar situation but our water supply was different. The requirements on our reservoirs were dramatically different than they are today. Our water system is very resilient for one and a half to two years, but when you start having dry years stacked one on top of each other, reservoir storage starts going down. We keep eating into reservoir storage. That’s why the third and fourth years become so critical and stressful.”
DWR’s press release reported that Lake Oroville in Butte County, the State Water Project’s principal reservoir, is at only 39 percent of its 3.5 million acre-foot capacity. Shasta Lake north of Redding, California’s and the federal Central Valley Project’s largest reservoir, is at 38 percent of its 4.5 million acre-foot capacity. San Luis Reservoir, a critical south-of-Delta reservoir for both the SWP and CVP, is at a mere 33 percent of its 2 million acre-foot capacity.
With no end to the drought in sight, DWR on Jan. 31 set its allocation of State Water Project water at zero. The only previous zero percent allocation was for agriculture in the drought year of 1991, but cities that year received 30 percent of requested amounts. This is the first time the allocation has been set at zero across the board.
Despite the “zero” allocation, DWR has assured the public that water essential for health and safety will still be delivered. And nearly all people and areas served by the State Water Project also have other sources of water, but most of these also are stressed by three successive dry years.
“The final State Water Project allocation for calendar year 2013 was 35 percent of the slightly more than 4 million acre-feet of water collectively requested by the 29 public agencies that deliver water to more than 25 million Californians and just under a million acres of irrigated agricultural land. The last 100 percent allocation — difficult to achieve even in wet years because of Delta pumping restrictions to protect threatened and endangered fish — was in 2006,” the release stated.
DWR went on to say that, “Deliveries will be boosted if storms produce enough rain and snow to boost reservoir storage and the snowpack.”
Contact Dawn Hodson at 530-344-5071 or firstname.lastname@example.org. Follow @DHodsonMtDemo on Twitter.