All signs point to good water year in countyJan 7, 2018 By Katie Roenigk, Staff Writer
It's still too early to make definitive predictions, but so far the water year in the Wind River Basin is off to a healthy start.
"All in all we're doing quite well," National Weather Service hydrologist Jim Fahey said Friday.
"We're setting up just fine."
Multiple components are involved in making that determination, he said, including the amount of snowpack in the Wind River Mountains, the level of moisture in the snow and soil, water storage in local reservoirs, and base flows in area waterways.
The numbers for all of those areas are average or above average, Fahey said, crediting the carryover that resulted from heavy snows last winter, flooding in the spring and a relatively mild summer that likely kept some snowpack intact above 11,000 feet while also preserve the soil-moisture content.
"We have so much water in the system now," he said.
Plus, he continued, the current water year - which started in October - began with a lot of precipitation followed by a warm spell that initiated a "mini snow-melt cycle."
"It wasn't pronounced like we see in the spring, but it helped melt some of the snow and increased the soil-moisture component (even more)," he said. "That kind of set the table."
Precip, snow depth, SWE
From October through December, Fahey said the Wind River Basin saw 120-130 percent of average precipitation. In December alone, he said the amount of precipitation that fell in the basin was 160-170 percent of average.
"That's looking at lower elevation stations and Snotel stations," he said.
Higher up, he said snow depths are also are high. At the end of the day Thursday, for example, Togwotee Pass, at 9,580 feet above sea level, had 58 inches of snow - 123 percent of median.
Last year at this time, Fahey said, there was 54 inches of snow in the same location.
He pays more attention to snow-water equivalents, though.
"I don't look at (snow depths) too much," Fahey said. "It's all about the water in the snow."
The SWE at Togwotee this week was 146 percent of median, compared to 125 percent around the same time last year, he said.
Closer to Lander at Townsend Creek, 8,700 feet above sea level, the snow depth was 17 inches - or 81 percent of median - but the SWE was 100 percent of normal, compared to 95 percent at around the same time last year.
No snow lately, or soon
The overall SWE recorded Friday in the Wind River Basin was 136 percent of median compared to 122 percent of median at around the same time last year, Fahey said.
This year's SWE has been falling steadily, however, from 156 percent of median Dec. 4, to 147 percent Dec. 11, 145 percent Dec. 18 and 144 percent Dec. 27 and now to its current level.
"We haven't got a lot of snow (lately)," Fahey said Friday. "And the last month or so of snowfall has been powdered sugar stuff - not so much moisture."
The forecast doesn't call for much more precipitation in the near future, either. Fahey said there may be a dusting over the weekend, with another chance for snow in the middle of next week. But after that it could be dry and warm for several weeks.
The situation is normal for Wyoming, Fahey said, where winter tends to be relatively mild - at least moisture-wise - until March.
"(That's) what we're accustomed to," he said, adding, "Last year we flip-flopped - our wet season was December to March."
The unusual events of last winter led to early flooding due to warm Chinook winds in February. Fahey said those winter-time floods aren't likely to come again this year.
"Even if we melt out (in February) we're not going to get the same amount of water ... unless we get the snowpack like we had last year on South Pass and in the foothills," he said.
As of Jan. 1, all of Fremont County's reservoirs were holding more water than average, according to the Natural Resources Conservation Service.
"We have great storage," Fahey said.
There was 620,200 acre-feet of water in Boysen Reservoir on Jan. 1, up from 604,600 acre-feet at the same time last year and 119 percent of average.
Boysen's capacity is 596,000 acre-feet. After that, water managers utilize the reservoir's flood pool, which isn't actually a separate pool but is merely the term for a certain elevation range in the reservoir, according to previous reports.
As of Jan. 1, Pilot Butte Reservoir held 103,900 acre-feet of water, up from 39,800 last year and 138 percent of average. Pilot's normal capacity is 151,800 acre-feet.
Bull Lake held 103,900 acre-feet of water Jan. 1, up from 39,800 last year and 138 percent of average.
The normal capacity for Bull Lake is 151,800 acre-feet.