The Central Nebraska Public Power and Irrigation District is lowering lake levels on its Supply Canal system to conserve storage water in Lake McConaughy.
Central plans to significantly reduce releases of storage water from Lake McConaughy and use water already in the Supply Canal and associated regulating reservoirs, including Johnson, Plum Creek, Jeffrey and Midway lakes, to supply irrigators during the last deliveries of the season. Deliveries are scheduled to end on Sept. 2.
Johnson Lake's water level will begin to recede on Aug. 12 and is expected to decline by up to eight feet by the end of the month, says Dave Ford, Central's irrigation manager.
Central supplies surface irrigation water from Lake McConaughy for clients in Gosper, Phelps and Kearney counties. The Central system also has led to groundwater recharge in those counties and other areas of south central Nebraska.
However, drought and dwindling North Platte River inflows have left Lake McConaughy at only half its storage capacity.
Other Supply Canal lakes above Johnson Lake will also decline from normal levels during the drawdown period:
• Jeffrey Lake near Brady will decline by approximately four feet;
• Midway Lake near Cozad will drop about two feet;
• Plum Creek Lake south of Lexington will be down about two feet.
The lakes will slowly rise after the end of diversions by other irrigation canals along the Platte River. Lake levels are expected to be back to normal by mid- to late-September, depending upon the availability of natural flow in the Platte River.
In response to low water supplies at Lake McConaughy, Central's irrigation customers were limited to 10 inches per acre this irrigation season. Normal deliveries are 15 to 18 inches per acre over 12 weeks.
Central implemented similar measures during the drought that persisted from 2002 to 2008. The efforts helped conserve tens of thousands of acre-feet of water at Lake McConaughy.
The amount and timing of lake level declines may change, depending upon irrigation demands and the amount and location of any rainfall in the area, Ford says.