JACKSON - With soggy sidewalks and roadways leading to depleted reservoirs, how is anyone to know whether the state is still in a drought?

The science of establishing drought conditions is tricky, and involves many variables. The most important variable? People.

"If you're in a desert and no one's there, it could not be considered a drought," Jan Curtis, the state's climatologist, said.

A drought is determined in part by looking at historic numbers. Experts look at current reservoir levels, stream flows, soil moisture and periods of rain and snow. That information is then compared to historic numbers, Curtis said.

Based on how rare conditions are, the drought is then given a classification. So, if a condition occurred just once in the last 100 years, it could be considered "severe" or "exceptional" drought.

If a reservoir has, say 60 percent of its average level, but that is the typical for a certain day, that can be interpreted as not being dry.

Still, Curtis emphasized that because more people are moving to the area, there are more demands on water and therefore drought conditions may be more frequent.

In Wyoming, about four times more moisture is evaporated than falls, making the state technically a desert.

"If it wasn't for the mountains and high elevations," Curtis said, "this state would be truly a desert."

And that evaporation rate leads to even more complex drought evaluation.

"If you live in a dry state that's always technically in a drought, how do you define a drought?" Curtis said. "It really is the impact on people."

Recent weather

The recent weather shift - bringing rain and cool temperatures throughout the state - began in earnest on April 12, Curtis said.

Even though there is tremendous green up, only three areas could be considered as out of the drought. Those are the middle of Fremont County, and the extreme southwest and southeast corners of Wyoming.

Curtis said there are short-term and long-term conditions that dictate a drought. For the short-term, drought is labeled by the impacts to non-irrigated lands. With all the green grasses growing, the short-term drought may be over.

"If soil moistures are good, the short-term drought is over," Curtis said. "That's on the surface. But drought is also looked at for subsurface soil moisture. Sometimes things look really good but … it might create a false sense of, 'We've recovered.' Appearances are kind of deceiving."

But the long-term drought is measured by overall water supply in reservoirs and streams - still a problem for many around the state.

"The overall trend is reservoirs, some are showing signs of recovery," Curtis said.

Reservoirs

John Lawson, the Bureau of Reclamation's Wyoming area manager, agreed, saying "We're starting to see some recovery out there and that's good for everybody."

Still, he said the state is not out of the hydrologic drought, with inflows and snowpacks still less than average on a daily basis. This, combined with the last five years of drought where reservoirs were depleted, means several more wet years are needed to get back to normal.

Among the most stressed areas, of course, are reservoirs along the North Platte. With Pathfinder at 21 percent of average and Seminoe at 56 percent, those will likely see lower levels as irrigation demands increase later in the summer.

"On the North Platte, do I see improvement? Yes I do," Lawson said. "I'm not expecting reservoirs to end up lower than last year, and I was expecting that earlier this year. It's happy news but far from OK."

With Pathfinder sitting at 210,000 acre feet and normal for this time of year is 714,000 acre feet, Lawson said if the reservoir were at normal levels, "I'd say we were back to recovery and more of a normal condition."

Still, the Boysen and Buffalo Bill reservoirs and faring very well.

Lawson said Boysen is expected to be "completely full" this year. And, in both reservoirs the BuRec has been releasing flows in excess of irrigation demands to make room for runoff.

"I anticipate once it warms up, we're going to have a good rush of inflows into the reservoir," he said.

Environmental reporter Whitney Royster can be reached at (307) 734-0260 or at royster@trib.com.