CHEYENNE - For those praying for an end to the recent string of dry years in Wyoming, hydrologist Ed Kouma of the U.S. Bureau of Reclamation didn't have a lot of good news to share Tuesday.

The weighted statewide average of the snowpack across Wyoming is only at 80 percent of its historical average for this time of year.

Although the snowy season is not necessarily over, any new snow will probably be more than erased by melting snow over the next couple of months, Kouma said.

And the currently low snowpack means that even reservoirs that are holding more water than average, such as Buffalo Bill Reservoir in Park County, will probably not fill up this year.

Kouma explained some details of the state's water forecast Tuesday to participants in the monthly water forum held in the state engineer's office.

Overall, he said, most people say Wyoming is heading into its sixth year of drought, although that can vary from one part of the state to another, and it also depends on how one defines "drought."

Kouma said Buffalo Bill is holding about 122 percent of the water it has historically held at this time of year. But the snowpack in the Shoshone River basin, which feeds the reservoir, is only at 60 percent of average, so it is unlikely that the reservoir will fill this year, leaving irrigators with less water than they need for an ideal growing season.

"If irrigators are conservative with their water supply and tighten up their operation as much as possible, these past few years they've gotten by, and this year is going to be like the last two years," Kouma said. "It's not that they haven't suffered, but they've handled it."

On the North Platte River, the projected outflow from Guernsey Reservoir in Platte County is 943,300 acre feet. The historical average outflow is 1.386 million acre feet, while anything less than 1.1 million acre feet means water must be rationed for downstream irrigators in eastern Wyoming and western Nebraska under the North Platte River decree.

"We do not anticipate an adequate supply of water for the irrigators" downstream from Guernsey, Kouma said.

He said the decree spells out which irrigators will get how much water when the outflow is less than 1.1 million acre feet. It uses a complex formula that takes into account factors such as historic use and the size of the conservation district.

"What that amounts to is everybody shares in the shortage," Kouma said.

He said irrigators can use information for projected streamflows and the details of the decree to estimate what their water supply will be for the growing season. Then, they can estimate how many days they will be able to irrigate, and they decide when to begin irrigating based on that information.

Many irrigators have been waiting until later in the growing season to begin irrigating during the past few dry years, Kouma said.

Wyoming snowpack

Here are percentages showing snowpack moisture content as of Monday, in relation to the 30-year historical average, along with figures from last year at the same time.

Basin Monday April 4, 2004

Snake River 75 75

Upper Yellowstone/Madison 72 76

Wind River 90 71

Big Horn 68 67

Shoshone 60 60

Powder/Tongue 81 73

Belle Fourche 47 19

Upper North Platte 92 67

Lower North Platte 83 67

Little Snake 96 71

Upper Green River 83 70

Lower Green River 101 58

Upper Bear River 107 58

Statewide (weighted) 80 69

Capital bureau reporter Bill Luckett can be reached at (307) 632-1244 or at bill.luckett@casperstartribune.net.