A red sun low over Slim Lake through wildfire haze, its reflection a column of orange on the water

Reservoirs in Wyoming

80 of 731 measured Wyoming lakes (11%) are man-made reservoirs in the USACE National Inventory of Dams. 47 carry a High or Significant hazard rating.

Reading the Wyoming reservoir landscape

80 reservoirs in Wyoming appear in the USACE National Inventory of Dams. That's a meaningful share — reservoir lakes carry their own ecology and access patterns distinct from natural lakes, including managed water levels, drawdowns timed to the dam's purpose, and shoreline mix dominated by structures built post-impoundment.

Wyoming's reservoirs serve a mix of purposes — flood control, water supply, hydroelectric power generation, navigation, and recreation often co-exist on the same impoundment, with one designated as the primary and others as secondary. The operating rules (pool levels, release schedules, drawdown timing) follow the primary purpose, which shapes everything from shoreline access through fish-population dynamics through year-round recreational use patterns.

The USACE National Inventory of Dams (NID) catalogs every dam in the United States above a size threshold — typically 25 feet in height or 50 acre-feet in maximum storage, plus all dams classified as high-hazard regardless of size. The reservoir records below pull NID fields (year built, hazard class, maximum storage, surface area at normal pool, dam length, primary purpose) and pair them with water-quality data where the impoundment also appears in EPA's lake-monitoring inventory.

Why these Wyoming reservoirs were built

Irrigation

Water Supply

Fish and Wildlife Pond

Flood Risk Reduction

Recreation

Hydroelectric

Other

Fire Protection, Stock, Or Small Fish Pond

Total reservoirs

103,740

Total surface acres

3,797,887

Normal storage (ac-ft)

High or Significant hazard

All 80 Wyoming reservoirs (by surface area)

Reservoir	County	Surface area	Year built	Purpose	Hazard
Glendo Reservoir Lacustrine Littoral	Platte	23,320 ac	1958	Flood Risk Reduction	High
Glendo Reservoir Lacustrine Pelagic	Platte	23,320 ac	1958	Flood Risk Reduction	High
Keyhole Reservoir	Crook	9,411 ac	1952	Flood Risk Reduction	High
Buffalo Bill Reservoir Riverine Littoral	Park	8,324 ac	1905	Fish and Wildlife Pond	Low
Fremont Lake	Sublette	5,400 ac	1993	Irrigation	Low
Wheatland Reservoir Lpd	Albany	4,792 ac	1964	Irrigation	Low
Lake Hattie	Albany	3,032 ac	1912	Irrigation	Significant
Big Sandy Reservoir	Sweetwater	2,510 ac	1952	Flood Risk Reduction	High
Alcova Reservoir Lacustrine Pelagic	Natrona	2,471 ac	1938	Hydroelectric	High
Guernsey Reservoir	Platte	2,380 ac	1927	Hydroelectric	High
Woodruff Narrows Reservoir	Uinta	2,312 ac	1962	Irrigation	High
Boulder Lake	Sublette	1,676 ac	1964	Irrigation	Significant
Viva Naughton Reservoir Lpd	Lincoln	1,460 ac	1967	Water Supply	High
Hawk Springs Reservoir	Goshen	1,328 ac	1925	Irrigation	High
Upper Sunshine Reservoir Lpd	Park	1,156 ac	1942	Irrigation	High
Lower Sunshine Reservoir	Park	1,049 ac	1972	Irrigation	High
Pilot Butte Reservoir Lpd	Fremont	900 ac	1926	Irrigation	High
Rob Roy Reservoir	Albany	801 ac	1986	Water Supply	High
Goshen Hole Reservoir	Goshen	787 ac	1957	Irrigation	Significant
Sulphur Creek Reservoir	Uinta	632 ac	1964	Irrigation	High
Hog Park Reservoir	Carbon	598 ac	1986	Water Supply	High
Bump-Sullivan Reservoir	Goshen	441 ac	1924	Irrigation	Significant
Wheatland Reservoir	Platte	424 ac	1960	Irrigation	Significant
Lake Cameahwait	Fremont	414 ac	1973	Fire Protection, Stock, Or Small Fish Pond	Low
Gelatt Lake	Albany	334 ac	1972	Fish and Wildlife Pond	Low
Park Reservoir	Sheridan	318 ac	1958	Irrigation	High
Saratoga Reservoir	Carbon	277 ac	1960	Recreation	Low
Meadowlark Lake	Big Horn	276 ac	1938	Recreation	High
Healy Reservoir	Johnson	246 ac	1975	Irrigation	High
Rollins Reservoir	Uinta	200 ac	1907	Irrigation	Significant
Granite Springs Reservoir	Laramie	190 ac	1904	Water Supply	High
Kemmerer City Reservoir	Lincoln	183 ac	1942	Water Supply	High
Burlington Lake D	Campbell	145 ac	1908	Water Supply	Low
Wardell Reservoir -D	Big Horn	141 ac	1972	Irrigation	Significant
Crystal Reservoir	Laramie	136 ac	1922	Water Supply	High
Frye Lake	Fremont	134 ac	1940	Irrigation	High
Little Sage Creek Reservoir	Carbon	132.3 ac	1969	Debris Control	High
Lak Reservoir	Weston	126 ac	1952	Irrigation	Significant
Lake Owen	Albany	120 ac	1963	Water Supply	High
Beck Lake D	Park	110 ac	1970	Irrigation	Significant
Teton Reservoir	Carbon	105.9 ac	1966	Recreation	High
Jim Bridger Pond	Sweetwater	96 ac	1989	Water Supply	Significant
Crompton Reservoir D	Uinta	94 ac	1954	Irrigation	Significant
Upper North Crow Reservoir	Laramie	94 ac	1932	Water Supply	High
Worthen Meadows Reservoir	Fremont	92 ac	1958	Water Supply	High
Twin Lakes Reservoir D	Sheridan	81 ac	1998	Water Supply	High
Deaver Reservoir -D	Park	80 ac	1918	Fish and Wildlife Pond	Low
Sawmill Reservoir D	Sheridan	75 ac	1972	Irrigation	High
Mortenson Lake D	Albany	71 ac	1970	Irrigation	Low
Renner Reservoir D	Big Horn	70 ac	1950	Irrigation	Low
Tie Hack Reservoir	Johnson	63 ac	1997	Water Supply	High
Luce Reservoir	Park	62 ac	1912	Irrigation	Low
Wallis Reservoir	Carbon	60 ac	1904	Irrigation	Low
Piedmont Reservoir D	Uinta	55 ac	1902	Irrigation	Low
Muddy Guard Reservoir	Johnson	48 ac	1976	Irrigation	High
Bell Reservoir	Albany	41 ac	1957	Irrigation	Low
Sederlin Lake	Carbon	40 ac	1910	Irrigation	Low
Atlantic Rim Reservoir	Carbon	38 ac	1981	Water Supply	Low
Rock Lake	Platte	37 ac	1930	Irrigation	Low
Sibley Lake	Sheridan	34 ac	1938	Recreation	High
Unnamed Reservoir	Big Horn	34 ac	1969	Irrigation	Low
Mayland Pond	Big Horn	34 ac	1969	Irrigation	Low
Leazenby Lake D	Albany	32 ac	1915	Fish and Wildlife Pond	Low
Pine Cone Reservoir D	Carbon	31 ac	1976	Irrigation	Low
Rawlins Reservoir	Carbon	31 ac	1956	Water Supply	Low
Soda Lake D	Albany	30 ac	1945	Irrigation	Low
Spring Lake D	Carbon	29 ac	1970	Other	Low
Tippecanoe Reservoir -D	Park	29 ac	1908	Irrigation	Low
Horseshoe Reservoir	Big Horn	28 ac	1969	Fish and Wildlife Pond	Low
Shirley Basin Reservoir D	Carbon	27.79 ac	1941	Flood Risk Reduction	Low
Graham Reservoir	Uinta	26 ac	1945	Irrigation	Low
Morrison Reservoir	Platte	16 ac	1975	Irrigation	Low
Rawlins Peaking Reservoir	Carbon	15 ac	1965	Water Supply	Low
City Reservoir	Park	12 ac	1929	Water Supply	Significant
Hogan Reservoir	Park	8 ac	1911	Irrigation	Low
A And M Reservoir	Sweetwater	6 ac	1978	Fish and Wildlife Pond	Low
Sundance Fairgrounds Pond	Crook	4 ac	1987	Irrigation	High
Hanna Reservoir	Carbon	4 ac	1934	Other	Low
Lower North Crow Reservoir	Laramie	—	1910	Water Supply	Significant
Pathfinder Reservoir	Natrona	—	1911	Fish and Wildlife Pond	High

Frequently Asked Questions

How many reservoirs are in Wyoming?

80 of 731 measured Wyoming lakes (11%) are man-made reservoirs in the USACE National Inventory of Dams. 47 are rated High or Significant hazard, meaning failure would put downstream lives or property at substantial risk. The oldest matched dam dates to 1902.

What's the largest reservoir in Wyoming?

The largest matched reservoir in Wyoming is Glendo Reservoir Lacustrine Littoral in Platte County at 23,320 acres of normal surface area, impounded by the Glendo Dam (completed 1958).

What's the difference between a reservoir and a natural lake?

A reservoir is a body of water impounded by a man-made dam — typically built for flood control, hydroelectric power, water supply, irrigation, or recreation. A natural lake formed without human intervention, usually from glacial scouring, volcanic activity, or river meandering. Reservoirs typically have shoreline that fluctuates with seasonal water level management, while natural lakes have more stable shorelines. The USACE National Inventory of Dams classifies every regulated dam in the United States, which is how we identify which LakeQuality lakes are actually reservoirs.

What does the hazard class mean?

USACE assigns each dam a hazard potential classification based on what would happen downstream if the dam failed — NOT how likely the dam is to fail. "Low" hazard means dam failure would cause no probable loss of life and only low economic loss. "Significant" means probable loss of life is unlikely but appreciable economic damage would occur. "High" means probable loss of life and significant economic damage. The classification is about consequence, not condition. Many High-hazard dams are perfectly safe; they're rated High because populated areas have grown downstream over time.

Where does this reservoir data come from?

Every reservoir record on this page is matched to the USACE National Inventory of Dams (NID), the federal database of all dams ≥25 ft tall or impounding ≥50 acre-feet, plus any dam that poses a Significant or High hazard regardless of size. The NID is published by the U.S. Army Corps of Engineers and updated annually. Surface area, storage capacity, dam height, and hazard classification come directly from NID records.

Where to stay near Wyoming reservoirs

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More on reservoirs and water quality

Are Reservoirs Cleaner Than Natural Lakes?

Dam-built reservoirs and natural lakes compared side by side on the same nutrient and algae measurements — the gap, the reasons behind it, and the exceptions.

Do Deeper Lakes Have Better Water Quality?

Surveyed maximum depth against nutrient and algae readings: the pattern, the shallow lakes that still read clean, and why land use beats bathymetry.

Lake Water Quality Explained: What the Readings Mean

How nutrient and algae readings are read against EPA ecoregion condition classes, what each class means in the water, and why a clean reading is not a clearance.

Why Lakes Turn Green: Phosphorus and Nutrient Pollution

How phosphorus and nutrient runoff drive algae growth and turn lakes green, where the nutrients come from, and what it means for a lake’s readings.

Data source

Reservoir data from the USACE National Inventory of Dams (NID), the federal database of all regulated dams. Dam attributes (height, year completed, storage capacity, hazard class) are matched to LakeQuality lakes by proximity and dam-name similarity. Some lakes may be reservoirs that aren't matched if the dam record uses a name substantially different from our lake name.