Irrigation outlook remains positive


MILLS – Water amounts flowing down the North Platte River are expected to remain at sufficient levels for the 2017 growing season, according to a recent report from the U.S Bureau of Reclamation.
“We will have average to higher than average reservoir levels, due to above average carryover storage in the reservoirs and slightly above average inflows,” said Carlie Ronca, Bureau Area Manager for Wyoming, in a release dated June 13.
That outlook hasn’t changed substantially from May projections, said Mahonri Williams, chief of the Bureau’s Resource Management Division in Mills on Monday.
“We still have very good carryover and good reservoir storage,” Williams said. “We’re anticipating an ample water supply (this year) and good carryover into
next year.”
Water releases from the reservoirs along the North Platte River system have increased slightly, due to the influx of water from ongoing snowmelt at higher elevations, he said. Outflow amounts are “higher than average,” Williams said, “but not as high as we’ve had in some of the past years.”
As of June 13, water was flowing over the spillways at the Kortes and Alcova dams, because there was more water than could be diverted through the power plants on the river, he said. Spillways are the only other outlets on those structures to move water out of their reservoirs and on through the system.
Anyone driving on U.S. Hwy. 85 south of Torrington will also have noticed fluctuations in the level of the North Platte as it flows under the bridge near the Western Sugar Plant. Those fluctuations can be attributed to regular daily variations in water level due to evaporation, extraction of water by vegetation along the riverbanks and changes in irrigation diversion upstream, he said.
“I don’t know the magnitude of change you can expect to see but, especially on a hot day, it’s a natural phenomenon,” Williams said. “The river can fluctuate during the day.”
As of June 13, water releases from the Seminoe Dam and through the Miracle Mile increased to about 4,500 cubic feet per second, according to the release. That level is expected to decrease by the end of June.
Below Pathfinder Dam, the average release is about 4,300 cfs with about 4,000 cfs moving through the Gray Reef Dam. The outflow from Gray Reef will vary throughout the summer in response to irrigation demands downstream, the
report said.
The reservoir at Glendo was about a foot below the top of the active conservation pool and was rising slightly. But Glendo water levels are not expected to enter the exclusive flood control pool.
At Guernsey, the Bureau is releasing about 4,100 cfs, both to manage reservoir levels and to satisfy irrigation demands downstream. The outflow is expected to remain steady through the end of June, with increases to 5,200 cfs in early July in response to downstream demands.
While there’s still some snow left to melt and be added to the system, most of the lower-elevation snow has melted. Williams said he believes inflow to the system is nearing its close for the 2017 season. And that bodes well for areas downstream concerned with potential flooding, he said.
“There’s still some water left to come, but I’m thinking we’re getting close to the down side of the inflows,” Williams said. “We’re anticipating we won’t need to make any big increases in our flows. We’ll be able to hold where we are or gradually decrease as inflows decline.”
Temperatures during the first half of June averaged four to eight degrees warmer than normal, according to a report dated June 16 from the weather prognostication company AccuWeather. Combined with less-than average rainfall in portions of the Great Plains and upper Midwest already this season, there’s a possibility of drought conditions developing later this summer, based around a high-pressure area developing over north central Colorado. The greatest drought potential would be in the eastern Dakotas, eastern Nebraska, Iowa and parts of Minnesota, the AccuWeather report said.
Drought impacts could be greatest on urban areas – lawns and gardens in the cities, for example. But, with irrigation water supplies typically restricted to croplands, grazing areas on ranches could also be impacted, should drought conditions manifest, Williams said.
Chances are, though, drought conditions would be limited to those portions of the upper Midwest to the east of this area, if they develop at all, said David Levin, a meteorologist with the National Weather Service forecast center in Cheyenne. A high-pressure cell developing somewhere over the region isn’t an unusual occurrence during summer months, Levin said.
It’s something that happens virtually every summer and doesn’t necessarily point to increased potential for a lack of precipitation leading to drought
conditions, he said.
“In fact, the climate prediction center three month outlook is forecasting above normal temperatures, but also above normal precipitation,” Levin said. “It looks like the area from northern Nebraska into the Dakotas is expected to experience slightly above normal precipitation amounts. It doesn’t look like we could forecast significant drought conditions.”


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