Drought monitor: 95% of state abnormally dry or worse

Angus M. Thuermer Jr., WyoFile.com via Wyoming News Exchange
Posted 5/5/21

Only parts of Sheridan, Johnson, Big Horn and Park counties are at or above normal moisture levels.

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Drought monitor: 95% of state abnormally dry or worse


Ninety-five percent of Wyoming is abnormally dry or worse, according to a nationwide drought monitor map released Thursday.

The pervasive dryness may have significant near-term impacts on grazing and irrigation, and could result in down-stream calls on Wyoming water as early as next year, experts say.

The current conditions statewide mark a seismic shift from a year ago when only 2 percent of the state registered abnormally dry or drier, according to the National Drought Mitigation Center at the University of Nebraska-Lincoln.

The driest areas — classified as “extreme drought” and covering 6 percent of Wyoming — span parts of Carbon and Natrona counties, plus small areas in Sweetwater and Fremont counties. There, a poor snowpack will produce runoff “inadequate for ranching and farming,” the center says.

Only parts of Sheridan, Johnson, Big Horn and Park counties are at or above normal moisture levels.

The monitor map, updated monthly, shows “exceptional” D4 drought — the driest condition on the center’s scale — in parts of Utah and Colorado and other areas of the southwest, but not Wyoming. 

Western residents are already feeling the effects. Early season wildfires in the Black Hills of South Dakota caused Gov. Kristi Noem to declare a state of emergency there through June 1. Southwestern water scarcity along the Colorado River may curtail water use in other states but shouldn’t affect Wyoming this year, said Steve Wolff, head of the State Engineer’s Office Interstate Streams Division. 

Lake Powell was at elevation 3,562.26 feet on May 1, and Wyoming will not have to release water from reservoirs until Powell drains to 3,525 feet, Wolff said. “Nothing will happen on that front this year,” he said.

Approaching summer, there’s still potential for relief for the state, said Jim Fahey, a hydrologist with the Natural Resources Conservation Service in Casper.

“It’s all highly dependent on spring moisture — May and early June,” he said. “I’ve seen Wyoming come out of a drought or go into a drought rather quickly,” he said.

But, “it takes a while,” he said, “to get out of deep drought.”

This week remote monitors measured the water content of the snowpack statewide at 89 percent of median, according to Fahey’s weekly report. The Powder and Tongue rivers in the northeast had the highest readings at 129 percent and 124 percent of normal respectively. The Upper Bear River Basin in western Wyoming measured lowest at 57 percent of median.

Water content is one indication of potential runoff. But snowmelt must first saturate dry soils before it flows into creeks, streams and rivers.

“Even though the snowpack is almost 100 percent, runoff (could be) 50 percent, give or take,” Wolff said. “A lot of that water is just going to soak into the ground.”

Fahey agreed. “A lot of the runoff numbers,” he said, “are going to be lower, even in some areas that have decent snowpack.”

The U.S. Department of Agriculture sees a “very good chance” for an early runoff with below–average stream flows, perhaps only 80 percent of typical volumes statewide, the agency predicted in April. 

The drought map shows that about 40 percent of Wyoming suffers from moderate, D1, drought, a level in which hay and forage yield is low, fire danger is elevated, fewer wildflowers bloom and less irrigation water is available.

“Severe, D2, drought” affects another 39 percent of Wyoming, stressing trees and reducing water pressure in some wells. In D2 drought, pastures are poor, overgrazing occurs and producers begin to sell cattle, according to the center.

See-saw changes in recent weeks saw areas west of the Continental Divide dry out. “Much of that area, especially in Teton County, was the one part of the state that had been doing quite well in terms of the drought map,” said Tony Bergantino, acting director at the Water Resources Data System in the Wyoming State Climate Office.

But last week severe drought, D3, moved into Teton County for the first time since 2016, he wrote in an email. That severe drought also grew to cover a large area of Lincoln County. 

The U.S. Department of Agriculture Farm Service Agency’s Wyoming office already is administering some drought assistance programs in western Wyoming and continuing others from last year, said Annie Bryce, farm program specialist.

Producers this summer could face “some tough drought conditions,” said Derek Grant, spokesman at the Wyoming Department of Agriculture. “They are a resilient bunch who are good at managing these conditions and know where their important decision points are,” he wrote in an email. 

Some federal agencies have told stockmen and women that livestock grazing may have to be curtailed this year, the department wrote in a newsletter. Producers should document drought and losses with time- and date-stamped pictures, Grant said. 

Colorado River Basin troubles

Irrigators and other water users in the Green River drainage will likely be  on edge for a while, interstate water chief Wolff said, because of extreme drought downstream along the Colorado River.

“Certainly, in the state we know it’s a very dry year,” he said. That will likely lead to more regulation on streams and rivers, especially in western Wyoming, Wolff said.

Inflow into Lake Powell is expected to be 45 percent of normal this year, he said. A U.S. Bureau of Reclamation prediction  that the reservoir will drain to the trigger elevation of 3,525 feet in early 2022 — a distinct possibility — would directly affect Wyoming.

“In the Upper Basin (Wyoming, Colorado, Utah and parts of New Mexico and Arizona) we’re kind of in a monitoring-discussion mode,” he said. “We are a year out before we have to take any action. 

“Depending on what next winter looks like,” he said, “we could be in serious trouble.”

Temperatures since 2000 have been about 2 degrees warmer than the 20th century average and are one average likely warmer than at any time in the past 2,000 years, the Bureau of Reclamation said on a climate change page of its website. Regulators will determine in August whether Lake Mead will drop below its trigger elevation of 1,075, at which point Arizona, Nevada and Mexico — but not yet California — would have to curtail use.

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