With winter in full swing, the mountains of Nevada and Colorado should be seeing snowfall that will melt to form the state’s water supply next year.
But early reports show we’re seeing a dry winter – and that comes on the heels of a dry winter in 2020.
Now, according to the U.S. Drought Monitor, more than 90 percent of Nevada is seeing severe to exceptional drought conditions.
So what does that mean for the coming year?
Jeff Anderson is a hydrologist with the U.S. Department of Agriculture. He monitors snowpack conditions from Reno.
"Right now, we have snowpacks that are below median. They’re about 69 percent of median for the Truckee, Tahoe and Carson basins, even less at 46 percent for the Walker and Upper Humboldt – 72 percent,” Anderson told KNPR's State of Nevada.
The below-normal snowpack is adding to the below-normal precipitation last year.
“For the eastern Sierra, we’ve missed half an average water years’ worth of precipitation in the last 15 months," he said, "There are certainly shortages in how much water we’ve been receiving from the clouds that go back more than a year.”
Anderson explained that the storm track from the Pacific Ocean that brings moisture to the coast is pushing further north into the Pacific Northwest.
But it is not all bad news, Anderson said there is a chance that the storms will move enough.
“There is still a chance that the storm track can dip south,” he said.
It has happened in the past. Storms move just enough south for Northern Nevada to benefit.
Even if large storms don't come, Bill Hauck with the Truckee Meadows Water Authority said it is unlikely that water supplies for the agency's customers will change.
“Just because we have below-average snowpack right now, and the runoff forecasts aren’t looking as good as we would like, doesn’t necessarily mean we’re going to have reduced river flows or supply in the Truckee River,” he said.
Hauck explained that the Truckee River system is backed up by several upstream reservoirs, the largest being Lake Tahoe, that can hold onto water from wetter years to beef up supply for drier years.
“They’re really just a major buffer against any effects of drought for at least two or three years, even a major drought,” he said.
Since 2017 and 2019 were wetter years, they made up for the drier years between 2012 and 2015.
The snowpack numbers are fed through a complex model of water use and supply, Hauck explained, and those projections show an 80 percent chance of normal river flow this year.
There has been more concern about the water supply from the Sierra Nevada because of the impacts of climate changes.
However, Anderson said that snowpack is not a good indicator of climate change especially on the eastern slope of the mountains. He said the snow levels vary widely and have since the snowpack was first measured in the early 1900s.
But Anderson does say he has seen bigger swings between wet and dry years.
“What I’ve been seeing is just the variability of what mother nature can throw at us both on the dry side and on the wet side as really expanded in just the last seven years since I’ve been down here,” he said.
In Southern Nevada, water comes from Lake Mead, which is fed by the Colorado River. The river is fed by melting snow from the western slopes of the Rocky Mountains.
Unlike Northern Nevada, the Colorado River is managed by a complex set of partnerships between western states that rely on it. Before water flows into Lake Mead, it is released from Lake Powell in Utah.
“So right now, we’re projecting about 8.23 million acre-feet to be released from Lake Powell this water year. We don’t expect that to change even though the forecast isn’t looking too good for inflow into Lake Powell,” said Dan Bunk, chief of Boulder Canyon Operations Office for the U.S. Bureau of Reclamation.
Bunk said that release of water is about average.
But Southern Nevada is already in a water-shortage reduction as outlined by the Drought Contingency Plan signed by Colorado River water users in 2019.
Under the agreement, Nevada must take a reduction of 8,000 acre-feet of water and Arizona must take a 192,000 acre-feet reduction.
The Drought Contingency Plan outlines very specific cutbacks for each state depending on where water levels are.
“Looking ahead, these current agreements expire in 2026, and so we’ll begin a process with our partners in the lower basin to develop new guidelines, in which case, through this collaborative process, we’ll take a look at impacts of lessening supply and hopefully continue to develop new tools in addition to the ones that we have to help whatever shortages and water supply that might occur in the future,” he said.
One of the most important tools in maintaining the water supply has been conservation. Las Vegas has been a model city for its conservation measures and water recycling efforts.
“The efforts by Southern Nevada Water Authority have been really helpful to prop up Lake Mead’s elevation,” Bunk said.
Through those efforts and the efforts of other states, he said about 3 million acre-feet of extra water has been stored in Lake Mead. All of that water has helped keep the lower basin of the Colorado River out of shortage for the past several years, he said.
Jeff Anderson, hydrologist, U.S. Department of Agriculture; Bill Hauck, Water Supply Administrator, Truckee Meadows Water Authority; Dan Bunk, Chief, Boulder Canyon Operations Office, U.S. Bureau of Reclamation
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