Glendo Reservoir Water Level
Glendo Reservoir is at 4,598.46 ft today (Oct 31), 36.54 ft below its 4,635 ft full pool, up 1.06 ft this week.
Wyoming · North Platte River
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Water level history
About Glendo Reservoir
Glendo Reservoir is a reservoir on the North Platte River in Wyoming, operated by U.S. Bureau of Reclamation. Its full summer pool sits at 4635 ft above sea level. Live water levels come from the U.S. Army Corps of Engineers (CWMS) and update hourly.
Understanding Glendo Reservoir's water level
Glendo is the last large reservoir in Reclamation's North Platte system. The river's seven main stem reservoirs run from Seminoe, Kortes, Pathfinder and Alcova down through Gray Reef to Glendo, and below it only the much smaller Guernsey remains, about 25 miles downstream, where Glendo's water is stored again and reregulated before it reaches irrigated land in eastern Wyoming and Nebraska. Glendo is the only storage facility of the Glendo Unit of the Pick-Sloan Missouri Basin Program, and its level follows that job closely. In winter releases are normally cut back to a low flow of about 25 cubic feet per second, so the lake climbs through winter and spring on snowmelt and water passed down from the upstream dams. Releases usually start in April to fill the Inland Lakes, four off stream reservoirs on the Interstate Canal, and irrigation deliveries carry on through summer. The yearly low tends to arrive in late September. Wyoming State Parks puts the average swing at about 55 feet a year.
Top of active conservation is 4,635 feet, the level the state park treats as full. The 18 feet above it, up to 4,653 feet, is an exclusive flood pool of 271,017 acre feet, and once the lake rises into that space the Army Corps of Engineers' Omaha District directs releases rather than Reclamation's Wyoming Area Office in Mills. Reclamation's current tables put storage at 492,022 acre feet at 4,635 feet and 763,039 acre feet at 4,653, which is also the crest of the ungated concrete spillway. The top of the dam is 4,675. Daily records go back to water year 1946. The high is 4,650.94 feet on 28 May 1973, about two feet short of the spillway crest, and the low is 4,548.10 feet on 28 September 1966, when just 15,140 acre feet remained. In 2011 the lake entered the flood pool on 1 June, peaked at 4,639.95 feet on 4 July with nearly five feet of water in flood space, and stayed there until 13 August. In summer 2015 the dam was raised three feet with a parapet wall and the dikes on the south side six feet.
Reclamation started looking at the site in 1944, but interstate fighting over the North Platte held construction off until December 1954. Nebraska worried about the supply reaching Lake McConaughy, and Congress withheld money until the states agreed on how the reservoir would be used. The National Park Service says the earthfill dam, 190 feet high and 2,096 feet long, was finished in the fall of 1957 and dedicated on 9 June 1959; building it meant moving three miles of railroad and four miles of highway. The powerplant opened with 24,000 kilowatts and was upgraded to 38,000 between 1980 and 1984 with new turbines and windings, and it runs seasonally on irrigation releases. The whole lake sits inside Glendo State Park, 22,000 acres with more than 500 campsites in 19 campgrounds and six launch areas. State Parks calls Glendo one of Wyoming's top walleye fisheries. Game and Fish's 2025 forecast pointed to strong numbers of 14 to 18 inch walleye, channel catfish often past 30 inches, and crappie and perch held down by walleye predation and a gizzard shad winterkill in 2023 to 2024.
Glendo Reservoir — frequently asked
What is Glendo Reservoir's full pool elevation?
4,635 feet, the top of active conservation storage. Reclamation's current tables put 492,022 acre feet in the lake at that level. Everything from 4,635 up to 4,653 feet is exclusive flood pool, another 271,017 acre feet reserved for runoff, so a reading above 4,635 means Glendo is holding flood water and the Corps of Engineers is directing releases. The bottom of the conservation pool is 4,570 feet.
What is the record high at Glendo Reservoir?
4,650.94 feet on 28 May 1973, with 758,830 acre feet in storage, the highest in Reclamation's daily record that begins with water year 1946. That put the lake almost 16 feet into the flood pool and about two feet below the spillway crest at 4,653. The big recent year was 2011, when Glendo peaked at 4,639.95 feet on 4 July and sat in the flood pool from 1 June to 13 August. The gauge on this page only keeps about six years of readings, so its high and low are recent marks, not these records.
What is the lowest Glendo Reservoir has been?
4,548.10 feet on 28 September 1966, when storage fell to 15,140 acre feet, only a few feet above the top of dead storage at 4,545. Recent lows are far higher. In water year 2024 the lake bottomed out at 4,582.13 feet on 26 September, about 53 feet below full, after peaking in May below the full pool mark.
Why does Glendo drop so much every summer?
Glendo exists to store water for release downstream. Releases usually begin in April to fill the Inland Lakes on the Interstate Canal, then irrigation deliveries through Guernsey to users in Wyoming and Nebraska continue into September. Below 4,635 feet, outlet releases are generally held under 5,500 cubic feet per second to protect the stilling basin. The drawdown typically bottoms out in late September, and State Parks puts the average yearly swing at about 55 feet.
When does Glendo Reservoir refill?
Over winter and spring. After irrigation season Reclamation normally shuts releases down to the low flow outlet, which passes about 25 cubic feet per second to the wetlands below the dam, so inflow accumulates for months. The peak usually comes with snowmelt in late spring or early summer: 4,635.79 feet on 24 June 2023, just over full, and 4,639.95 feet on 4 July 2011. In drier years like 2024 it tops out below full.
Who decides releases when Glendo is in flood pool?
Once the lake rises above 4,635 feet into the exclusive flood pool, the Omaha District of the Army Corps of Engineers directs releases in coordination with Reclamation. The three main outlet gates can pass 13,000 cubic feet per second with the powerplant off, and the spillway handles 10,335 at 4,669 feet. The Corps credited Glendo with $90.5 million in flood damages prevented from 1965 through 2011.
How much power does Glendo Dam generate?
Glendo Powerplant has two units totaling 38 megawatts, up from 24 megawatts originally after new turbines and windings were installed between 1980 and 1984. At full pool the two units together can pass about 3,400 cubic feet per second. The plant runs seasonally, mostly while irrigation water is being sent downstream, and it is operated remotely.
Other lakes near Glendo Reservoir
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