Other Dams, Reservoirs & Power Plants – Nebraska & Wyoming
By Gary Stone, Nebraska Extension Water & Integrated Cropping Systems Educator
This will be a six-part series on the dams, reservoirs, power generation and some diversion dams located on the North Platte River. This last part will cover the remaining dams and power plants in Nebraska and Wyoming.
Built in the 1950s, the Dave Johnston power plant is located near Glenrock, Wyo. This coal-fired power plant uses North Platte River water for cooling. Combined energy produced from the four steam-powered generators is 922.2 megawatts. The power plant is operated by PacifiCorp and scheduled to be decommissioned in 2027.
The Laramie River Station power plant is located north of Wheatland, Wyo. on the Laramie River. The Laramie River is a major tributary to the North Platte River. Constructed in the 1970s, the coal-fired power plant went fully online in 1982. The plant’s three steam-powered generators produce a combined output of 1,710 megawatts. The electricity produced is delivered to the Missouri Basin Power Project, whose participants include Basin Electric, Tri-State Generation and Transmission Association, The Lincoln Electric System, and the Wester Minnesota Power Agency / Missouri River Energy Services.
In addition to the Laramie River Station, the Grayrocks dam and reservoir was constructed to supply cooling water for the power plant. The 104,000 acre-feet reservoir also provides recreational opportunities, flood control, and wildlife habitat.
Next is Kingsley Dam and Lake McConaughy or “Big Mac” located north of Ogallala. Kingsley dam construction started in 1936 and completed 1941. Kingsley dam is named after George Kingsley, a Minden banker and businessman. Kingsley dam is the second largest hydraulic filled earthen dam in the world. The dam is over three miles long and 162 feet high. The dam base has interlocking sheet steel pilings 30 to 160 deep down to the Brule clay layer. The dam core consists of a mixture of loess soil and water pumped to form the dam. The mixture was allowed to dry, forming the dam. In the process doing this, Lake Ogallala was formed from the pumped loess mixture, just below the dam. The water facing side of the dam is layered with 180,00 “jackstones” and limestone rock from Wyoming. The jackstones look like the toy jack, a six-pointed stone, weighing over eight hundred pounds each.
Lake McConaughy or “Big Mac” reservoir formed behind Kingsley Dam. Lake McConaughy named after C.W. McConaughy, a grain merchant and mayor of Holdrege. Both McConaughy and Kingsley had a vison of supplemental irrigation for the south-central Nebraska area and the dam and lake / reservoir became a reality. The lake is the largest in the state, has a capacity of 1,948,000 acre-feet, is twenty-two miles long, over three miles wide, and covers over 30,000 acres at capacity. In addition to providing irrigation and hydro-power generation, Lake McConaughy / Lake Ogallala provides a major recreational site for camping, boating, fishing, and windsurfing as well as wildlife habitat.
The construction for the Kingsley dam power plant started in 1981 and went online in 1984. There is one generator with a 51,900-kilowatt capacity. Central Nebraska Public Power and Irrigation District (CNPPID), a political subdivision of the State of Nebraska, owns the dam and manages the hydro-power plant at the dam.
Water from the reservoir irrigates approximately 109,000 acres in Gosper, Phelps, Kearney, Lincoln, and Dawson counties through over five hundred miles of canals and laterals. This water delivered through the Supply Canal to the three main irrigation canals E65, E67, and Phelps starting at Central’s Diversion Dam on the Platte River.
CNPPID also has three hydro-power plants along the Supply Canal. These are the Jeffery, with two 10,800 kilowatt generators, Johnson No. 1 with two 10,030 kilowatt generators, and Johnson No. 2 with one 22,960-kilowatt generator. The power generated by CNPPID is sold to Nebraska Public Power District.
There are twenty-six smaller lakes along the Supply Canal. Some of these lakes are private, but others are open to the public. These lakes provide additional recreational opportunities and wildlife habitat. The Nebraska Game and Parks Commission manage the designated Wildlife Management Areas and the recreational areas around these lakes and Lake McConaughy.
The last power plant we will address is the coal-fired Gerald Gentleman Station, located south of Sutherland, Neb. This is Nebraska’s largest power plant, using both North and South Platte River water for cooling. The plant was commissioned in 1979 with a combined output of 1,365 megawatts for the two steam-powered generators. The plant is owned by Nebraska Public Power District and is consistently ranked as one of the lowest production-cost plants in the nation.
The waters in the reservoirs of the North Platte River serve multiple purposes. Initially most were constructed for irrigation and hydro-power generation. As time progressed, additional beneficial uses for recreation, flood control, wildlife habitat, sediment retention, and endangered species became reality. Conflicts between states over water have resulted in compacts, decrees, and interstate agreements to settle these disputes. For a full review of these, visit CompactAndDecrees2010.pdf (nebraska.gov), from the Nebraska Department of Natural Resources. The waters of the North Platte River serve many beneficial uses. Proper management of this finite resource will ensure these uses are there for the future.
Arneson, Joe, “Building Nebraska’s Biggest Lake”, Building Nebraska’s Biggest Lake | PBT (plattebasintimelapse.com)
Central Nebraska Public Power and Irrigation District website, The Central Nebraska Public Power and Irrigation District (cnppid.com)
Dave Johnston Power Plant, Dave Johnston Power Plant, US (power-technology.com)
Dave Johnston Power Plant, Dave Johnston Power Plant - Global Energy Monitor (gem.wiki)
Gerald Gentleman Power Plant, Gerald Gentleman Power Plant, US (power-technology.com)
Laramie River Power Plant, Laramie River Power Plant, US (power-technology.com)
Nebraska Public Power District, Gerald Gentleman Station, Coal (nppd.com)
Wyoming Municipal Power Agency, WMPA Generation - Wyoming Municipal Power Agency