Ample water available for 2011 irrigationWritten by Christy Martinez
With snowpack in Wyoming continuing to hover between 102 and 139 percent of average, it seems there will be no shortage of irrigation water this growing season.
In the April 4 snow report by the Natural Resources Conservation Service, the Wind River Basin recorded the state’s low snow water equivalent (SWE) of 102 percent of average, while the Upper North Platte and Upper Bear River basins claimed the high at 139 percent.
In the first week of April, 10 Wyoming basins gained average SWE, while one basin stayed the same and only two lost SWE.
“The snowpack is right up around 105 percent of average, and it’s been staying pretty high so far this year,” says Shoshone Irrigation District Manager Bryant Startin of his area in northwest Wyoming that irrigates from Buffalo Bill Reservoir. “The reservoir right now is fairly full, and the Bureau of Reclamation started releasing water on April 1 to make more room for the anticipated inflows to the reservoir this spring.”
The released water has increased flows on the Shoshone River from 350 cubic feet per second (cfs) to 1,000 cfs.
“We’ll start irrigating by mid-April, and most districts are looking to turn on the water on April 18,” says Startin. “The Bureau will increase the river somewhat when we start irrigating, to 1,300 cfs.”
Over the last several years the Shoshone has ran as much as 5,000 to 6,000 cfs under evacuation conditions to make room for spring runoff.
In the March 2011 Wyoming Spring Snowmelt Flood Potential Outlook, issued March 24, many basins in the state are forecast at low to moderate flood potential. The Shoshone River Basin is one that’s forecast to have moderate to high flood potential, with the highest potential across the extreme upper portions of the North Fork of the Shoshone River.
“Current SWE trends are slightly above the 30-year normal, and are below the record SWE years of 1996 and 1997, but are above the SWEs that produced record runoff in 1981 and 1991,” says the report.
Although ice is still thick and there hasn’t been a good measurement since last fall, Wheatland Irrigation District Manager Don Britton says their Reservoir #2 is holding 57,400 acre-feet, Reservoir #1 has 8,340 acre-feet and Reservoir #3 is sitting at 60,000 acre-feet.
“The snowpacks are way up there on the charts, and we’re expecting high inflows and flooding this spring,” says Britton of his area in southeast Wyoming.
Britton says his district has released a little water from their reservoirs, but not to the extent of the Bureau of Reclamation’s releases.
“We had a record year last year – the gauge at Bosler was installed in the 1930s, and last year showed the highest flows measured on it since it was installed,” he states. “Hopefully it doesn’t outdo that this year, but the snowpack is there to do it, and it’s gone up every day.”
Britton says word is that the Snowy Range area is still gaining snowpack.
“The water content in one drainage in the Snowy Range is 37.3 inches of water. There are a few in the 30s, and several in the 20s,” he notes. “Imagine a large area with close to 40 inches of water sitting on top of it.”
Those high water measurements contribute to the forecasted high potential for headwater spring snowmelt flooding across the Upper North Platte River Basin.
“Current SWE trends are near the record SWE years of 1982, 1986 and 1997, and well above the SWE trends of 2009 and 2010,” says the Flood Potential Outlook. The Laramie River Basin also has high potential for spring snowmelt flooding, as does the Little Snake River Basin in southern Wyoming.
The Upper Bear River Basin in western Wyoming has a high potential for flooding, as well, with SWEs above the record SWE years of 1986 and 1995.
Of moisture on the croplands over the winter, Startin says growers in his area have had decent snow cover for some of the winter, as well as spring moisture in the last month.
“The farmers’ biggest challenge now is getting out in the field, because it’s still cold and things haven’t really thawed yet,” he says. “They’re trying to get grain planted now, and get other things ready to go.”
Britton says Wheatland-area farmers have been progressing with fieldwork, with most of the barley planted and oats in progress.
“Everything’s pretty well farmed up that they’ll plant,” he says. “We had two or three really cold snaps with bitter cold, but for the month of March it opened up and was mild.”
The Shoshone Irrigation District recently finished up a large winter project. With funding from the Wyoming Water Development Commission (WWDC), the district was able to line about 600 feet of concrete tunnel, which was over 100 years old, and a 300-foot section of their canal with high-density polyethylene (HDPE) pipe, a hard plastic that’s said to last for years.
“It’s about 70 feet below the invert of the canal to the top of the pipe we had for the tunnel, so we would have had to dig a big hole to replace the concrete,” says Startin.
Britton says projects over last winter with the Wheatland Irrigation District were repairs to flood damage from last year.
Of the 2011 growing season, Startin says, “I think it will be a fairly good year, on the supply side of things.”
“It looks like a year that we’ll have plenty of water again,” says Britton.