Big Mac just about full

HOLDREGE, Neb. — The Central Nebraska Public Power and Irrigation District's water manager has stopped counting the times he has been asked one particular question the past few months: Are we full yet?

The “we” referred to actually is an “it”: Lake McConaughy.

People want civil engineer Cory Steinke to tell them if Nebraska's largest reservoir has fully recovered from a drought early this decade that dropped the lake to around 20 percent of capacity. The result was limited hydropower production and lower allocations for irrigators for five years.

Steinke's answer at Tuesday's meeting of the district's board was that Lake McConaughy soon will be as full as it's allowed to be over the winter under the district's Federal Energy Regulatory Commission license.

The lake now holds more than 1.55 million acre-feet of water and is just 40,000 acre-feet below the federal limit for Oct. 1-April 25. (An acre-foot is the amount of water needed to cover an acre of land to a depth of 1 foot.)

“I'm sorry to say that it's not river conditions. It's the Wyoming reservoirs spilling. I don't think the (North Platte) river is there (recovered) yet,” Steinke said.

“We're going to run our hydros all winter as long and as hard as we can,” he said.

That still might not cause the lake to fall much below the maximum elevation allowed, 3,260 feet above sea level, because upstream federal Bureau of Reclamation reservoirs are nearly full and continuing to send water downstream.

Steinke said some climatologists are predicting a La Niña weather pattern over the winter, which usually brings cool, wet weather to the mountains that are home to the Platte River Basin's headwaters. “That's favorable to us,” he said.

He anticipates a spring spill of water from the upstream reservoirs to make room for snowmelt.

“I'd like to have some room (in Lake McConaughy) to catch that,” Steinke said, but that will depend on winter conditions for operating the hydros.

All those factors mean there will be a full water supply for irrigators in 2011 and high river flows downstream of Lake McConaughy all winter.

Neither Steinke nor other water managers had predicted such reservoir recoveries going into spring.

“We weren't looking at all that way into May,” Steinke said. At that time, he'd predicted near-average lake inflows of 840,000 acre-feet.

His new estimate for 2010 is 1.43 million acre-feet, or at least 140 percent of average. That would be the ninth-largest volume of inflows for the lake. In contrast, 2008 recorded the ninth lowest.

Current inflows are 277 percent of average for early September. Inflows will drop as irrigation deliveries and return flows to the North Platte River from Panhandle farms end.

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