January 18, 2017 - By Christine Souza - Strong early January storms brought a wealth of increased precipitation and snow, especially in Northern California, which caused a leap in snowpack totals and reservoir storage, and helped to replenish groundwater aquifers. For water managers and farmers alike, the storms raised questions about whether they set the pattern for a wet winter to come—and whether that would ultimately lead to improved water supplies in the coming year.

(Left) Aerial photograph shows standing water on farmland south of Sacramento near Galt, following several days of heavy rainfall known as an “atmospheric river.” January storms also brought sharp increases in the Sierra Nevada snowpack and in reservoir storage. 
Photo/Don Cameron

In a week's time, the Sierra Nevada snowpack swelled from about two-thirds of average levels to more than 60 percent above average. Reservoir managers were forced to release water in order to accommodate runoff from the January storms, but many key reservoirs remained near or above average storage levels for the date.

While encouraged by the sudden improvement in the water outlook, state Department of Water Resources officials cautioned that California's peak rainfall season still has two and a half months ahead. In addition, many parts of Southern California remain mired in drought (see story).

California Farm Bureau Federation President Paul Wenger noted that even a return of average or above-average precipitation would not guarantee restored water supplies for many farmers, due to constraints required to benefit protected fish and wildlife.

"The recent rain and snow have given us a natural reprieve from the 2012-15 drought. It will be up to the regulators of our water resources to see if that translates into a reprieve from the regulatory drought the San Joaquin Valley and Southern California have been forced to endure," Wenger said.

Some of the most severe restrictions during the drought have come in the western San Joaquin Valley, where agricultural customers of the federal Central Valley Project have seen their water allocations reduced to zero for two years, and 5 percent last year. At the Westlands Water District, which supplies CVP water to farmers, Gayle Holman called any amount of rainfall or snowpack extremely welcome.

"We have an abundance of rainfall and blizzard conditions in the Sierra, so for us, any type of snowpack adds to water supply," Holman said. "Our growers can only look upward."

The U.S. Bureau of Reclamation is expected to issue its initial 2017 water supply outlook for the CVP this week, during its annual Mid-Pacific Region Water Users' Conference in Reno, Nev.

Elsewhere in the Central Valley, farmer Jeff Marchini of Merced, who serves as a director of the Merced Irrigation District, said inflow into Lake McClure from the Merced River has been "tremendous" since Jan. 1, and that the lake had risen to 65 percent of capacity.

"We are in a very good position compared to where we were last year, when we were sitting around 8 to 10 percent of capacity," Marchini said.

The recent "atmospheric river" storms pummeled parts of the state, starting in early January, bringing rain, heavy winds and flooding. A second round of storms arrived last week, which added to the collected moisture, causing creeks and rivers to exceed flood stage, but also bringing several feet of snow in the Sierra.

Doug Carlson, a spokesman for DWR, said improved snowpack figures are consistent in the northern, central and southern parts of the Sierra Nevada range, adding, "It's looking pretty good as far as the snow water equivalent is concerned."

What snow surveyors record between now and April 1 will guide state officials in managing water supply, Carlson said, cautioning that "it's much too soon to start projecting the end of the drought."

Regarding the storm's impact on reservoirs, Carlson said total reservoir storage stood at about 112 percent of average by the end of last week.

"Precipitation is also looking pretty good," he said, noting that the pace of precipitation was exceeding that of California's wettest year on record, which occurred during 1982-83. At this time in 1983, the average amount of rainfall was about 32 inches, compared to 42 inches as of last week, Carlson said.

In the western San Joaquin Valley, Holman said the region has had "some wonderful rainfall."

"The word I'm getting from farmers is, 'Yeah, there's some flooding right now in our fields, but it is welcomed,' and is allowing growers to use that natural rainfall to irrigate their crops," she said. "They are able to allow Mother Nature to irrigate the fields, which hasn't occurred since 2011."

Holman added that during times of excessive rainfall, "we need to be able to capture that water and we need a place to store it. Given the fact that so many of our river systems are in flood conditions, if we had a place to divert that water into storage, that would help benefit not just agriculture, but people and communities, fisheries, everyone." (See related Comment.)

Regarding groundwater, DWR spokeswoman Lauren Hersh said the agency has monitoring stations that measure groundwater, but "it takes so long for the groundwater to actually seep down into the aquifer, that we're not going to feel an impact yet. There's so much surface water and precipitation that we've been capturing in the reservoirs that it will probably ease up on groundwater pumping, which is always a positive."

Starting with a better water supply for the year, coupled with the addition of the new Sustainable Groundwater Management Act regulations, Marchini said he expects most growers to be focused on recharging groundwater aquifers.

"This is going to help with recharge of what has already been pumped. I think people are going to be idling their deep wells so that we can get some recovery in the basins," Marchini said. "All of that is good for the future."

At Terranova Ranch in Helm, Don Cameron has been constructing a project on his farmland that would divert excess surface water to recharge the groundwater basin.

While still finalizing agreements and permits for the project, he said if the improvements were in place today, "we would be able to relieve the Kings River and lower drainage from flooding. If we could take 500 cfs (cubic feet per second) off of the Kings River, that helps everybody downstream, plus we'll be ponding it up on the farmland and recharging groundwater, so there's a dual benefit."

(Christine Souza is an assistant editor of Ag Alert. She may be contacted at csouza@cfbf.com.)
Reprinted with permission: California Farm Bureau Federation