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Storms leave best water outlook in half-decade

Storms dislodge hyacinth from Tuolumne

Heavy flows on the Tuolumne River in Modesto, California, have cleared out water hyacinth, a nonnative plant that degrades fish habitat and boating, in January, 2017. (John Holland/jholland@modbee.com)
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Heavy flows on the Tuolumne River in Modesto, California, have cleared out water hyacinth, a nonnative plant that degrades fish habitat and boating, in January, 2017. (John Holland/jholland@modbee.com)

The soggy first half of January has water managers thinking that maybe, just maybe, the drought is finally ending.

The storms built the central Sierra Nevada snowpack to 163 percent of average as of Friday, according to the California Department of Water Resources. That is the main source for irrigation districts in the Northern San Joaquin Valley, and part of the city of Modesto’s supply.

The storm season could still slip to below average over the next two or three months, but for now, the mountains hold a heck of a lot of water. Weather watchers hope for even more rain and snow to further boost reservoirs and aquifers stressed by the drought that started in 2012.

One of the state’s leading water experts, UC Davis professor Jay Lund, was optimistic in a blog post Wednesday.

“In terms of surface water, most of California is no longer in drought,” he wrote. “The accumulated reservoir and soil moisture deficits of the last five years have been filled in most of the state.”

Lund, director of the Center for Watershed Science, cautioned that drought persists for some communities and that its effects on fisheries and Sierra forests could linger for years.

Don Pedro Reservoir on the Tuolumne River stood at 90 percent of capacity as of Friday. It would be even higher were it not for large releases to maintain space for possible big storms to come.

Don Pedro could reach capacity for the first time since 2011, even if dry weather sets in during the rest of the season, utility analyst Jason Carkeet told the Turlock Irrigation District board Tuesday.

TID and the Modesto Irrigation District, partners on Don Pedro, cut deliveries to about 40 percent of normal during the worst of the drought in 2015. They bounced back to about 75 percent the next year.

The Merced Irrigation District endured far worse, with virtually no surface water in 2015. It started to recover with last year’s moderate storms and got a big boost this month. McClure Reservoir went from 45 percent of capacity before the wet stretch to 66 percent Friday.

Flood control rules will require releases to keep the reservoir at no more than 67 percent this time of year. The district took the occasion to urge support for a long-sought project that would boost storage through higher spillways.

The storms’ effect on groundwater levels is not yet known, district spokesman Mike Jensen said by email, “but obviously the rain has been a benefit. As always, MID is taking advantage of every opportunity to use its recharge basins.”

New Melones Reservoir on the Stanislaus River is only a third full because of its higher requirement for downstream releases. Still, that’s about 800,000 acre-feet of water, and the Oakdale and South San Joaquin irrigation districts have rights to the first 600,000 acre-feet each year.

San Luis Reservoir, which stores water for much of the West Side, held 69 percent of its capacity after the storms. That’s good news for irrigation districts that in some cases were cut to zero or 5 percent because of drought and fish protections.

One of the January storms was especially warm and wet, raising concern about rain melting snow at high elevations and forcing even larger reservoir releases. But it was followed by heavy snow that ideally will melt slowly into early summer.

The federal Climate Prediction Center forecasts above-average rain and snow through January and average conditions into April.

Suggestions that the drought is done drew caution from other experts besides Lund. Among them was Michelle Mead, a National Weather Service meteorologist, who sends regular emails to the media and others.

“Yay for us,” she said of the deluges, “but keep in mind, we’re a long skinny state and we all have to receive beneficial precipitation to completely eliminate the state drought declaration!”

John Holland: 209-578-2385

By the numbers

163: Percent of average snowpack in central Sierra Nevada as of Friday

5: Percent of average for April 2015, the worst point during the drought

90: Percent of capacity that Don Pedro Reservoir has reached as of Friday

66: Percent at McClure Reservoir

35: Percent at New Melones Reservoir

69: Percent at San Luis Reservoir

Source: California Department of Water Resources

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