Irrigation season draws to a close

Rains, early shutdown signal decent carryover in system

MILLS – Planning ahead for the 2019 irrigation season, Fort Laramie and Pathfinder irrigation districts have informed the Bureau of Reclamation office in Mills of plans to close down water flow earlier than in previous years.

Mahonri Williams, chief of the Bureau’s Resource Management Division, said Friday water would stop flowing into the Fort Laramie Canal by early this week. While still waiting official confirmation from the irrigation district, Williams said the Pathfinder Canal would close down the 2018 irrigation season probably by the end of the week.

“The districts are going off a little earlier” this year, Williams said. “In recent years – years with good inflows and water supplies – it varies each year but they’ve typically delivered water into mid-September.”

Consequently, the Bureau of Reclamation announced Friday it would begin the annual “draw-down” of Guernsey Reservoir on Tuesday, immediately after the Labor Day holiday weekend. Boat owners are advised to take their watercraft out of the reservoir before the water becomes too low to access boat ramps.

Williams expects water levels to reach surface elevation of 4,591 feet – below even the lowest-water ramps – by Sunday, Sept. 9. Boats should be out of the reservoir by Saturday, Sept. 8, of not before.

The early irrigation shutdown is good news for next year’s irrigation season, meaning there will be above average water carryover in reservoirs, Williams said. The Bureau is predicting about 450,000 acre feet carryover in the Pathfinder system which supplies water to most of Goshen County and western Nebraska irrigators. 

While that’s more than the 40-year average of 400,000 a.f., it’s still significantly less than the 600,000 a.f. carried over from the 2017 irrigating season, Williams said. Part of the reason for the reduced carryover was reduced snowmelt inflows this past spring.

At Seminoe Reservoir – the furthest-upstream catchment on the system – spring flows totaled only about 400,000 a.f., about 57 percent of the average, due to the warm winter of 2017-18 and reduced snowfall in the areas that supply melt-water to the system. The story of the 2018 irrigation season could have had a much different ending if Mother Nature hadn’t cooperated in other ways this year.

“The inflows were well below average” in spring 2018, Williams said. “Good carryover from last year and some timely rains in the irrigation deliver area all combined to provide an adequate water supply this year.”

The worst-case scenario for irrigators – allocations – was talked about in the spring as one possibility for the 2019 growing season. Depending on what happens in coming months, it’s a possibility that remains on the table, Williams said. 

“If we have 450,000 a.f. in carryover storage, and we pick up some water in the winter time as water flows into the reservoirs, and if we have another low inflow year next year, an allocation could certainly be a strong possibility,” he said. “It depends on what the inflows are.

“The nature of the North Platte Basin is it varies greatly from year to year,” Williams said. “Sometimes we have low years that follow high years and it goes the other way, too. There isn’t really a strong pattern we can use to predict that. It’s just the variability of nature.”

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