Reclamation forecasts less snowmelt


MILLS – Despite assurances of sufficient irrigation water for the 2018 growing season, the Bureau of Reclamation is still predicting less than average water flowing into the North Platte River Basin in the form of melting snow.

According to the agency’s regular monthly snowmelt forecast, total April through July snowmelt runoff is predicted at 715,000 acre-feet, about 78 percent of the 30-year average above Glendo Dam.

Runoff projections have decreased slightly since early February, when the Bureau estimated spring inflows at 735,000 acre-feet, or 81 percent of the 30-year average. 

“I believe the circumstance was, when we were looking at snow conditions at the end of January and plugging that information in to (forecast models), we were anticipating a little bit more water in the Alcova-to-Glendo reach than in our current forecast,” said Mahonri Williams, chief of the Bureau of Reclamation Resources Management Division in Mills. “There were certain parts of the basin where the snow conditions were not quite as promising. That tends to influence our forecast down.”

On the bright side, storage content in all the reservoirs along the North Platte River in Wyoming totaled almost 2.2 million acre feet as of the end of March. That’s about 132 percent of the 30-year average for the system. Strong carryover from the 2017 irrigation season is in large part responsible for the abundance of water for the coming year.

“We anticipate the North Platte Basin water contractors will have a full water supply this year,” said Carlie Ronca, Wyoming area manager for the Bureau in Mills, in an April 6 press release.

The weather so far this year has been warmer and drier than normal, due in part to an unusual La Nina pattern, said Rob Cox, science and operations officer for the National Weather Service in Cheyenne. But that pattern is swinging toward a more neutral condition this spring and into early summer, according to information at the National Weather Service Climate Prediction Center website.

Overall conditions remain favorable for the upcoming growing season, Cox said. 

“At this point in time, looking at the drought outlook, I’m not seeing anything through April that’s going to be of concern,” he said. “They’re not looking at any big changes to the drought outlook at this time.”

As of April 3, the U.S. Drought Monitor (droughtmonitor.unl.edu) indicates no drought concerns for most of Wyoming, with just abnormally dry to moderate drought conditions in portions of south-central and extreme southwestern areas of the state. Climate prediction models don’t forecast any major changes in those classifications, at least through the end of April, Cox said.

“Beyond that, it’s hard to say what it’s going to do,” he said. “My guess would be, from the three-month outlook, temperatures should be right around or slightly above normal, with precipitation about the same.”

Management practices can be one of the most effective tools to address any challenges in agriculture, said Carrie Eberle, assistant professor of Agronomy and Cropping Systems at the University of Wyoming Sustainable Agriculture Research and Extension Center near Lingle. Alternate irrigation plans and even alternative crop selections can be used to deal with a possible water shortage down the road.

“My gut response is, if we’ve got water for this year, (producers) will use it,” Eberle said. “And we’ll see what happens next year.”

Whether a shortfall comes next year or not, there are things producers can do this year to prepare for a worst-case scenario – allocations. Certain crop varieties bred for increased drought resistance or that are quicker to mature can be used when there are questions about sufficient water, she said.

“If we’re trying to plan for 2019, it’s really hard to forecast it out,” Eberle said. “If a person is really concerned about it, this year, do business as usual. If we’re thinking next year we could be short on water, then put in a crop that’s going to be lower water use.”

Caleb Carter, extension agriculture educator with the Goshen County Extension Office in Torrington, agreed. Both also noted the importance of tailoring certain management practices to those longer-term plans or goals.

“You always have to be thinking ahead with herbicides, for example,” Carter said. Herbicide selection “could limit on crop rotations.”

Another way to “bank” water would be fall applications on already-harvested fields later this year. But that only works in soils high in clay, which will hang on to the water, Carter said. No-till or low-till farming and leaving crop residue on the ground to limit evaporation can also help. But some management schemes take pre-planning.

“Some of these strategies, you can’t just do on a whim,” he said. “When we’re thinking of a year when we might not have as much water, anything we can do to preserve moisture, to keep it in the soil, is beneficial.

“It’s a guessing game, which is the art form of farming,” Carter said. “It’s trying to guess what the best options will be for you to get things to grow.”

But it’s still too early to say for certain what impact current conditions will have on the future, Williams from the Bureau of Reclamation said. Rarely does snow-melt runoff actually hit the “average” levels – around 700,000 acre feet – in any given year. Typically, the amount is either much greater than average or much less.

The 2017 water year was one of those unusual exceptions, where inflows to the North Platte Basin from snowmelt runoff were almost at the average, Williams said. This year is shaping up to be below average, but there’s still time for additional water to make it into the system.

And the impact of normal spring storms in the demand for irrigation water can’t be predicted, he said. Overall, it’s just too early to know exactly what’s going to happen, particularly when looking forward to the 2019 irrigation season and worries about allocations,
Williams said.

“That’s a wait-and-see kind of questions,” he said. “Even though we predict a certain amount of inflow, we have to wait and see what we actually get. Nature doesn’t always give us what
we project.

“And it’s still April,” Williams said. “If we get the inflow we’re projecting, we wouldn’t have quite as much carryover this year as last year, but there’d still be useful carryover into the next water season.


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