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Reservoirs in Arizona

48 of 229 measured Arizona lakes (21%) are man-made reservoirs in the USACE National Inventory of Dams. 37 carry a High or Significant hazard rating.

Reading the Arizona reservoir landscape

48 reservoirs in Arizona 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.

Recreation is the headline purpose for the largest share of Arizona's reservoirs — lakes where the dam exists explicitly to create surface water for fishing, boating, and adjacent shoreline development. Pool levels are typically maintained more stably than at flood-control or hydro reservoirs, which supports fixed-dock access, consistent boat ramps, and the kind of shoreline economy that natural-lake counterparts in the state share.

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 Arizona reservoirs were built

Recreation

Fish and Wildlife Pond

Irrigation

Hydroelectric

Other

Water Supply

Flood Risk Reduction

Total reservoirs

224,161

Total surface acres

1,240,580

Normal storage (ac-ft)

High or Significant hazard

All 48 Arizona reservoirs (by surface area)

Reservoir	County	Surface area	Year built	Purpose	Hazard
Lake Powell	Coconino	160,784 ac	1963	Hydroelectric	High
Alamo Lake	La Paz	41,500 ac	1968	Flood Risk Reduction	High
Lake Pleasant	Yavapai	9,957 ac	1992	Flood Risk Reduction	High
Bartlett Lake	Maricopa	3,519 ac	1939	Water Supply	High
Lyman Reservoir	Apache	1,324 ac	1912	Irrigation	High
Saguaro Lake	Maricopa	1,265 ac	1930	Hydroelectric	High
Canyon Lake	Maricopa	950 ac	1926	Hydroelectric	High
Big Lake	Apache	518 ac	1964	Recreation	Significant
Willow Creek Reservoir	Yavapai	460 ac	1936	Irrigation	High
Sunrise Lake	Apache	307 ac	1967	Recreation	High
Patagonia Lake	Santa Cruz	260 ac	1968	Recreation	High
Hawley Lake	Apache	244 ac	1956	Recreation	High
Ashurst Lake	Coconino	230 ac	1954	Fish and Wildlife Pond	Low
Tempe Town Lake	Maricopa	214 ac	1997	Recreation	Significant
Watson Lake	Yavapai	202 ac	1920	Irrigation	High
Show Low Lake	Navajo	186 ac	1953	Other	High
Tunnel Reservoir	Apache	164 ac	1896	Irrigation	High
River Reservoir	Apache	164 ac	1896	Irrigation	High
Luna Lake	Apache	163 ac	1911	Irrigation	Significant
Concho Lake	Apache	155 ac	1927	Irrigation	Significant
Fool Hollow Lake	Navajo	152 ac	1956	Recreation	High
Willow Springs Lake	Coconino	150 ac	1970	Recreation	Low
Kinnikinick Lake	Coconino	145 ac	1956	Fish and Wildlife Pond	Low
Parker Canyon Lake	Cochise	133 ac	1962	Recreation	High
Horseshoe Lake	Apache	129 ac	1964	Recreation	High
Rainbow Lake	Navajo	118 ac	1904	Irrigation	Significant
Crescent Lake	Apache	104 ac	1934	Recreation	Low
Dogtown Reservoir	Coconino	81 ac	1934	Fish and Wildlife Pond	Significant
Black Canyon Lake	Navajo	78 ac	1964	Recreation	High
Kaibab Lake	Coconino	75 ac	1934	Recreation	Low
Bear Canyon Lake	Coconino	65 ac	1929	Fish and Wildlife Pond	Low
Lynx Lake	Yavapai	52.5 ac	1962	Fish and Wildlife Pond	High
Woods Canyon Lake	Coconino	51 ac	1956	Fish and Wildlife Pond	Low
Cataract Lake	Coconino	46 ac	1947	Recreation	Significant
Pena Blanca Lake	Santa Cruz	45 ac	1958	Fish and Wildlife Pond	High
Roper Lake	Graham	34 ac	1961	Recreation	High
Bunch Reservoir	Apache	27 ac	1929	Irrigation	Low
Goldwater Lake	Yavapai	23 ac	1932	Recreation	High
Bog Tank Lake	Apache	14.1 ac	1957	Recreation	High
Sante Fe Lake	Coconino	14 ac	1892	Water Supply	High
Kennedy Lake	Pima	14 ac	1973	Recreation	High
Green Valley Lake	Gila	10 ac	1996	Other	High
Bootleg Lake	Navajo	9.9 ac	1965	Recreation	High
Rose Canyon Lake	Pima	7.3 ac	1958	Fish and Wildlife Pond	Low
Granite Basin Lake	Yavapai	7 ac	1939	Recreation	High
Fain Lake	Yavapai	5 ac	1927	Recreation	Low
Horsethief Basin Lake	Yavapai	5 ac	1934	Recreation	High
Whitehorse Lake	Coconino	—	1938	Fish and Wildlife Pond	Low

Frequently Asked Questions

How many reservoirs are in Arizona?

48 of 229 measured Arizona lakes (21%) are man-made reservoirs in the USACE National Inventory of Dams. 37 are rated High or Significant hazard, meaning failure would put downstream lives or property at substantial risk. The oldest matched dam dates to 1892.

What's the largest reservoir in Arizona?

The largest matched reservoir in Arizona is Lake Powell in Coconino County at 160,784 acres of normal surface area, impounded by the Glen Canyon Dam (completed 1963).

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 Arizona 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.