Critical snowpack at 52% of normal
BY DENNIS WYATT
Even with the recent Pineapple Express that blew in through the 209 region, the snowpack is barely over half full, which means Central Valley residents will have to rely on water from other sources.
The Department of Water Resources’ most crucial snow measurement of the year was taken on April 1, which marks the official end of California’s rainy season for water delivery planning purposes. It showed the state’s snowpack at 52 percent of normal.
“A good March, but certainly not a great March,” noted state snow-survey chief Frank Gehrke on April 1 after measuring 32.1 inches at Phillips Station in El Dorado County at an elevation of 6,873 feet. “Despite recent storms, today’s snow survey shows that we’re still playing catch-up when it comes to our statewide water supplies. While today’s snow survey determined that the water content is much higher than February, the state will remain well below average for the year.”
That means much of California will be relying on water saved in reservoirs from the near-record 2016-2017 winter that ended the state’s 25 percent conservation order for cities that was in place for four years.
California’s exceptionally high precipitation last winter and spring resulted in above-average storage in 154 reservoirs tracked by the Department. DWR estimates total storage in these reservoirs at the end of March was 28.2 million acre-feet, or 107 percent of the 26.4 MAF average for this time of year.
The 52 percent of average snowpack — while significantly better than on March 1 — indicates the state may be slipping back into drought conditions. The United States Department of Agriculture Drought Monitor shows 42 percent of California is currently in drought conditions. That’s down from 48 percent in mid-March before a series of storms hit the state.
“These snowpack results – while better than they were a few weeks ago – still underscore the need for widespread careful and wise use of our water supplies,” said California Department of Water Resources Director Karla Nemeth. “The only thing predictable about California’s climate is that it’s unpredictable. We need to make our water system more resilient so we’re prepared for the extreme fluctuations in our water system, especially in the face of climate change.”
In addition to the manual surveys conducted at Phillips, DWR also logs electronic readings from 103 stations scattered throughout the Sierra. Electronic measurements indicate the SWE of the northern Sierra snowpack is 11.8 inches, 43 percent of the multi-decade average for April 1. The central and southern Sierra readings are 17.6 inches (60 percent of average) and 12.9 inches (50 percent of average) respectively. Statewide, the snowpack’s SWE is 14.6 inches, or 52 percent of the April 2 average.
The South San Joaquin Irrigation District that supplies water to Manteca, Lathrop and Tracy as well as irrigation water to farms around Manteca, Ripon, and Escalon expects to be able to make full deliveries based on snowpack on the Stanislaus River watershed.
That said, SSJID General Manager Peter Rietkerk has repeatedly advised urban and farm customers to use water wisely as there is no assurance that next the 2018-2019 water year will receive adequate snowpack meaning a carryover supply of water is a prudent move to protect against earnest drought conditions returning in the coming 18 months. Manteca had gone five years in drought conditions before last year’s above normal winter snowfall.
“Potentially, we’re living off our savings from last year so we have to be very prudent in our water use,” Gehrke said.
The snow station near Sonora Pass at 8,870 feet on the upper reaches of the Stanislaus River watershed had 60 inches of snow on April 1, with a water content of 19.7 inches. That is a big improvement over March 1 when the snow was at a quarter of normal with 26 inches of snow and 7.7 inches of water content.
The Central Sierra — the watershed critical to Northern San Joaquin Valley farms and cities — is rated as abnormally dry by the USDA Drought Monitor while San Joaquin County is considered to be in normal status due to rainfall while neighboring Stanislaus County to the south is rated as abnormally dry.
Since the governor’s emergency drought declaration was lifted, Californians are using almost as much water as before the previous drought. That has prompted the state to ramp up its messages to be thrifty with water.
The Tuolumne River watershed received just 0.24 inches of rain in December, compared to the historical average of 5.95 inches, and in February received 0.86, compared to the historical average of 5.99.
Despite the 21.57 inches of rain accumulated in the watershed since October being just 76.3 percent of the historical average, the March rainfall has helped improve that number. Prior to March, the watershed had received just 12.3 inches or rain, or 50.1 percent of the historical average.
The Modesto Irrigation District is expecting to give area growers an allotment of 42 inches of water, while the Turlock Irrigation District will be giving 48 inches.