After years of back-to-back drought, a historic — and in many cases, record breaking — volume of water has accumulated as snow in mountains across western Nevada and the Great Basin.
The snowpack, among the largest in the past 40 years, is providing the arid West and much of Nevada with a respite from prolonged drought. Reservoirs are refilling, boosting water supplies, and the moisture has left dry soils more saturated. At the end of 2022, the U.S. Drought Monitor reported nearly the entire state facing severe to exceptional drought. As of March, that measure had dropped to 5 percent, capping off a three-month period filled with continual winter weather.
The snowpack in Marlette Lake (above Lake Tahoe), Sonora Pass, which feeds into the Walker River, and Lamoille Canyon in the Ruby Mountains, hit all-time highs since snow volumes were first recorded about a century ago, according to the Natural Resources Conservation Service.
In many parts of the state, including the mountains that feed into the Carson and Walker rivers, Jeff Anderson, a hydrologist with the conservation service, said the snowpack surpassed the old records “by really large amounts — by like 20 to 30 percent more snow than we've seen before on April 1.”
“We have an incredibly strong snowpack, record setting in many locations,” he said.
But the strong snowpack, a relief for water managers, has emergency managers preparing for what could be a spring and summer of significant flooding as the snow melts and runs off into streams, rivers and diversions across the state. Already, flooding in rural communities through March contributed to an estimated $20 million in damages, according to state and local officials.
Flooding in central Nevada has made many roads impassable, temporarily cutting off the Yomba Shoshone Tribe from food and supplies in early March. When a big storm hit the state last month, precipitation turned into flood water that hit Eureka, threatening homes and isolating cattle, as flooding further east in Lincoln County threatened the state-operated Echo Canyon Dam and communities that lie beneath it. Lyon County saw major flooding in Smith Valley and in Dayton.
“We live in an arid desert, so every drought ends with a flood; I've heard that my entire career,” said David Fogerson, who leads the Nevada Division of Emergency Management and coordinates flood response. “It's a [natural cycle] that we have to figure out how we manage and live within. But it does seem like it is happening on a more frequent basis than what has happened in the past.”
Three years of consecutive drought, in addition to the overuse of a limited water supply, placed significant stress on water users, the environment and ecosystems. The sizable snowpack this year is expected to provide some breathing room, even as water users continue to grapple with overuse — more rights to water than there is water to go around — and increasing demand.
Across the West, many rivers are fed from snowpack, which acts as a natural reservoir, storing water at high elevations that is then released into creeks and streams as the snow melts in the spring. Along the Truckee River, which rises above Lake Tahoe and flows through Reno toward Pyramid Lake, officials expect key storage reservoirs to fill, creating a buffer for future dry years.
The high flows forecast to course through the Truckee River could improve conditions for the threatened Lahontan cutthroat trout and the endangered cui-ui, two fish species that have been historically blocked from their spawning grounds upstream with the construction in 1905 of the Derby Dam, the first project designed by what would become the U.S. Bureau of Reclamation.
For decades, the Pyramid Lake Paiute Tribe has worked to reintroduce and recover the species of fish, fighting in court to secure water rights, restore habitat and redirect water back to the lake after years of diversions toward the Carson watershed damaged Pyramid Lake’s ecosystem.
The high flows this year, according to Donna Noel, the tribe’s natural resources director, “will increase the elevation of the lake and also give enough flows to allow both the Lahontan cutthroat trout and cui-ui to spawn this year.” She said it will also help the Pyramid Lake Paiute Tribe prepare for dry years by storing water in Stampede Reservoir, which can be released in the future. Freshwater inflows into Pyramid Lake are also critical for maintaining water quality.
She said high water is important for fish to access spawning infrastructure.
“It's a function of how they constructed the dam and the spawning channel,” Noel said.
Anderson, with the Natural Resources Conservation Service, said questions remain about how the snow will melt in certain areas and what the long-term impact on water supply will look like — something that could be determined by whether next year is a dry year or another wet year.
This uncertainty could play out in the Humboldt River, where conditions were extremely dry until this year. The Humboldt is forecast to see potentially large inflows as a deep snowpack melts off into the creeks and streams that feed the river. But how will the dry conditions affect that flow?
“The Humboldt River had its worst runoff season ever last year,” Anderson noted in an interview. “To go from record dry to the second snowiest year ever, how is that going to play out?"
In the Sierra south of Lake Tahoe, record-breaking amounts of snow will melt in the Carson and Walker river watersheds. Over the past three years, water officials in both systems have had to manage for scarcity, as is often the case. As temperatures rise, more water is expected to melt than officials might be able to control, adding flood control to the job of irrigation districts.
“We don't have, along these river systems, a flood control district,” Fogerson said.
The Carson River flows from the eastern Sierra through Carson City into Fallon and wetlands throughout the area. But the river is impounded at Lahontan Reservoir — and the volume of forecasted snow melt far exceeds the dam’s storage capacity. Since early March, the Truckee Carson Irrigation District has been acting under emergency flood operations, evacuating water from the reservoir to make room for more water that is modeled to come flowing down the river.
The action is an about-face from last year, where allocations to water were cut to 85 percent. In any given year, Lahontan Reservoir can hold about 300,000 acre-feet of water (an acre foot of water is the volume of water that can fill 1 acre of land to a depth of 1 foot).
Last year, the irrigation district drained Lahontan Reservoir to about 4,000 acre-feet to fulfill water orders. This year, emergency managers and irrigation district officials expect to fill the reservoir three times.
Kelly Herwick, the Truckee Carson Irrigation District’s water master, shared a rule of thumb: “When it's showing a wet water year, think even wetter. When it's showing a dry water year, think even drier.”
The high snowpack could boost irrigators within the district, offering them the potential to receive additional water as the district works to quickly move water out of the reservoir. It will also benefit the Lahontan Valley wetlands — an important habitat for migratory birds — that are managed by the Fallon Paiute Shoshone Tribe, the Nevada Department of Wildlife and the U.S. Fish and Wildlife Service.
But damaging floods in Churchill County remain a significant concern.
The major variable facing emergency managers and water officials on the Carson and Walker rivers is the timing of the melt. If the melt is somewhat steady, then there will be more tools and infrastructure to handle the excess water. If the melt happens all of the sudden — because of warm weather or a rain on snow event — then more water could come down the river, and quickly.
“If we're running everything full, there's not much wiggle room for a breach,” Herwick said.
Another variable, contributing to flood risk for communities across the state, is low-elevation snowpack. This snow, spread out across a wider area, can melt more rapidly. And already, the melt has been delayed by winter storms, leaving a bottleneck of snow awaiting a big melt.
Officials point to Spratt Creek, the lowest snow survey site in the Carson River Basin. Where in many years it would have melted by this time of year, Anderson said the area has only started to melt — with about 20 inches of snow water content remaining, far more than the normal peak of about 6 inches.
Emergency managers are preparing now, bringing resources into rural communities. In late March, Churchill County held a town hall to discuss upcoming flood preparations and posted several takeaways. Officials are providing residents with sandbags, focusing on canal cleaning to avoid breaches and installing culverts under U.S. Highway 95. The county also approved construction of a new weir to help increase the capacity at which water can be moved from the reservoir.
When floods happen, they are often multicounty events, stretching resources across the state. Fogerson and other emergency managers said it was important that residents prepare for floods, checking online resources and getting their households ready ahead of time.
During the flooding in March, the American Red Cross of Nevada set up shelters and provided resources to rural communities that were cut off by the storms. The Red Cross helped prepare food and supplies, including baby formula, to the Yomba Shoshone Tribe, and established evacuation shelters in Lincoln County, faced with increasing concern that Echo Dam could fail.
Mary Powell, executive director of the American Red Cross in Northern Nevada, said her organization is already preparing by organizing resources, collaborating with emergency officials and recruiting additional volunteers — an especially important need in rural counties.
"We're working to understand where each county is at, so we can fill gaps,” she said.