CHEYENNE - The Wyoming State Engineer's Office says it expects more calls on water rights in the North Platte River drainage in the months ahead, despite recent heavy snowfall in the river headwaters.
That's because hydrologists continue to forecast less water stored in the river's reservoirs than the amount expected to be needed for irrigation. Heavy snow that fell in southern Wyoming and northern Colorado over the past six weeks or so still won't make up the difference.
The latest U.S. Bureau of Reclamation forecast predicts that upcoming runoff combined with existing water in Pathfinder and Guernsey reservoirs through July will total 800,000 acre-feet. That's 72 percent of the amount needed for irrigation.
An acre-foot is enough water to cover an acre with 1 foot of water.
Last month was one of the snowiest Aprils on record in southeast Wyoming. The mountains of southern Wyoming got up to 6 feet of new snow.
"April was glorious. The difference between the April forecast and the March forecast was very significant," Matt Hoobler, North Platte River coordinator for the State Engineer's Office, said Wednesday. "But it didn't bring us up to the 1.1 million."
The water content of snowpack ranged as high as 130 percent of average in some areas of the North Platte drainage but as low as 75 percent in others.
In February, State Engineer Pat Tyrrell issued the first wintertime call on water rights for Wyoming's portion of the river in eight years. The purpose was to help fill the reservoirs at the end of an unusually dry winter.
Tyrrell lifted the call May 1 as planned under the annual transition to water administration for irrigation.
Upcoming calls on water rights will be made on a case-by-case basis, Hoobler said. The calls are put in place to give holders of older water rights precedence to use water in the system; those with younger water rights are restricted from using the water.
A call on water rights might affect one tributary of the North Platte River but not others, he said.
"With the known short supply, our field staff is gearing up for a busy summer," Hoobler said.