Updated Aug 2026
Arizona Lake Water Quality
Water quality grades for 7 of the 229 lakes we list here, across 14 counties.
Grade Distribution
All 229 Arizona lakes in the index: 7 (3.1%) carry an A–F grade and 222 (96.9%) are not rated, because they lack enough recent nutrient or algae sampling to support a letter.
Lake Map
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Where to stay near Arizona's top-graded lakes
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Explore Arizona Lakes
Arizona reports, fishing & travel
Reservoirs in Arizona
View all 48 reservoirs →48 of 229 Arizona lakes (21%) are man-made reservoirs in the USACE National Inventory of Dams. 37 carry a High or Significant hazard rating. The oldest matched dam dates to 1892.
EPA-Impaired Lakes in Arizona
View all 19 impaired lakes →19 of 229 Arizona lakes (8%) are officially listed as impaired under Clean Water Act §303(d) in the most recent EPA ATTAINS reporting cycle. 7 have an approved Total Maximum Daily Load (TMDL) restoration plan.
Arizona Fishing & Recreation
Licenses, regulations, records, and where to fish across Arizona.
Counties
All 14 Arizona counties, ranked by average lake water quality. Compare them against every county nationwide in the county rankings, browse the full directory of graded lakes, or pick a different state.
Arizona Lakes Needing Attention
7 lakes7 graded lakes
| # | Lake | County | Grade | Clarity |
|---|---|---|---|---|
| 1 | DSunris Park Lake | Yuma | D | No recent samples |
| 2 | DWatson Lake | Yavapai | D | No recent samples |
| 3 | CRose Canyon Lake | Pima | C | 2.8 ft |
| 4 | CCanyon Lake | Maricopa | C | 3.4 ft |
| 5 | CLakeside Lake | Pima | C | 1.3 ft |
| 6 | BAk-Chin Reservoir | Pinal | B | No recent samples |
| 7 | BChaparral Park Lake | Maricopa | B | 3 ft |
7 of the 229 Arizona lakes in this index carry an A–F water-quality grade, spread over 14 counties. Those grades rest on measurements from the Arizona Department of Environmental Quality, alongside federal programs and volunteer monitoring networks. The rest are listed for their size, depth and location, without enough recent nutrient or algae sampling behind them to support a letter.
Lake Powell is the largest lake in this index at about 160,784 acres, one of 21 here that clear 500 acres. The rest run smaller, and small and shallow is where nutrient loading shows up first, because there is less water to dilute it and the bottom sediment stays within reach of the sun. Pinal ranks highest on average county grade (B), and Yuma sits lowest. With only 14 counties in the state, the cross-county spread is narrower than the within-county spread for most lakes.
Lake Match
Which lake suits how you actually use one?
Six questions — swimming, fishing, quiet, cabins, drive time — and a shortlist of graded lakes that fit, with the water quality behind each one.
Source: EPA National Aquatic Resource Surveys and the EPA Water Quality Portal.
More on lake water quality
A data snapshot of the lakes we grade: how the A–F distribution breaks down, the clearest and the greenest states, and where the water is improving.
How lakes are graded A–F on nutrients and algae using EPA ecoregion condition classes, what each letter means in the water, and why an A is not a clearance.
The cleanest and dirtiest U.S. lakes in the monitoring record, ranked on EPA nutrient and algae condition classes across thousands of graded lakes.
The clearest lakes in America, ranked by measured Secchi depth in feet from EPA monitoring data — and why the famously clear lakes are missing.