Updated Aug 2026
Oklahoma Lake Water Quality
Water quality grades for 157 monitored lakes across 60 counties.
Oklahoma has 157 graded lakes in our dataset, sampled across 60 counties, drawing on monitoring by the Oklahoma Department of Environmental Quality plus federal and volunteer measurements. Only about 0% of Oklahoma's lakes pull an A grade — the smaller, agricultural-watershed lakes that dominate the dataset tend to carry persistent nutrient loads. 15% of lakes fall in the D or F brackets.
The state's lakes lean eutrophic: enough nutrient input to support an active algal community, with the trade-offs in clarity and dissolved oxygen that come with it. The cleanest county on average is Grayson (grade C); the most-stressed is Pottawatomie. The gap between the top and bottom counties is large enough that "Oklahoma lake water quality" hides real local variation.
Grade Distribution
All 157 Oklahoma lakes in the index: 25 (15.9%) carry an A–F grade and 132 (84.1%) are not rated, because they lack enough recent nutrient or algae sampling to support a letter.
Where to stay near Oklahoma
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Top-Graded Oklahoma Lakes
The highest water-quality grades in Oklahoma — clarity, depth, and A-F grade at a glance.
Lake Map
Explore Oklahoma Lakes
Oklahoma reports, fishing & travel
Reservoirs in Oklahoma
View all 120 reservoirs →120 of 157 Oklahoma lakes (76%) are man-made reservoirs in the USACE National Inventory of Dams. 95 carry a High or Significant hazard rating. The oldest matched dam dates to 1902.
EPA-Impaired Lakes in Oklahoma
View all 90 impaired lakes →90 of 157 Oklahoma lakes (57%) are officially listed as impaired under Clean Water Act §303(d) in the most recent EPA ATTAINS reporting cycle. 21 have an approved Total Maximum Daily Load (TMDL) restoration plan.
Oklahoma Fishing & Recreation
Licenses, regulations, records, and where to fish across Oklahoma.
Counties
All 60 Oklahoma 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.
Top 25 Cleanest Lakes
25 lakes25 graded lakes
| # | Lake | County | Grade | Clarity | Trophic | Access |
|---|---|---|---|---|---|---|
| 1 | CLake Texoma | Grayson | C | 4.2 ft | Eutrophic | ✓ Public |
| 2 | CSarge Creek Lake | Kay | C | No recent samples | Eutrophic | ✓ Public |
| 3 | DLake Texoma | Marshall | D | 1.7 ft | Eutrophic | ✓ Public |
| 4 | DLake Texoma | Bryan | D | 3.2 ft | Eutrophic | ✓ Public |
| 5 | DLake Thunderbird | Cleveland | D | 1.7 ft | Eutrophic | ✓ Public |
| 6 | DGrand Lake | Delaware | D | 1.6 ft | Hypereutrophic | ✓ Public |
| 7 | DGreenleaf Lake | Muskogee | D | 2.5 ft | Eutrophic | ✓ Public |
| 8 | DLake Konawa | Seminole | D | 3.1 ft | Eutrophic | Not recorded |
| 9 | DWes Watkins Reservoir | Pottawatomie | D | 1.8 ft | Eutrophic | ✓ Public |
| 10 | DSpavinaw Lake | Mayes | D | 3.3 ft | Eutrophic | Not recorded |
| 11 | DCopan Lake | Washington | D | 1.6 ft | Eutrophic | ✓ Public |
| 12 | DEucha Lake | Delaware | D | 3.1 ft | Eutrophic | ✓ Public |
| 13 | DSportsman Lake | Seminole | D | 6.2 ft | Eutrophic | Not recorded |
| 14 | DWewoka Lake | Seminole | D | 2.5 ft | Eutrophic | Not recorded |
| 15 | DWashunga Bay Lake | Kay | D | No recent samples | Eutrophic | ✓ Public |
| 16 | DSandy Beach Lake | Osage | D | No recent samples | Eutrophic | ✓ Public |
| 17 | DCoon Creek Lake | Kay | D | No recent samples | Eutrophic | Not recorded |
| 18 | DOsage Cove Lake | Osage | D | No recent samples | Eutrophic | ✓ Public |
| 19 | DPioneer Cover Lake | Osage | D | No recent samples | Eutrophic | ✓ Public |
| 20 | DLake Nahni Waiya Tuskahomma | Pushmataha | D | No recent samples | Hypereutrophic | ✓ Public |
| 21 | DLake Sardis Clayton | Pushmataha | D | No recent samples | Hypereutrophic | Not recorded |
| 22 | DThunderbird Lake Hog Creek | Cleveland | D | No recent samples | Eutrophic | ✓ Public |
| 23 | DThunderbird Lake Fisherman'S | Cleveland | D | No recent samples | Eutrophic | ✓ Public |
| 24 | DLake Hugo Hugo | Choctaw | D | No recent samples | Hypereutrophic | ✓ Public |
| 25 | DFt. Cobb Lake | Caddo | D | No recent samples | Hypereutrophic | Not recorded |
25 Lakes Needing Attention
25 lakes25 graded lakes
| # | Lake | County | Grade | Clarity |
|---|---|---|---|---|
| 1 | DFt. Cobb Lake | Caddo | D | No recent samples |
| 2 | DLake Hugo Hugo | Choctaw | D | No recent samples |
| 3 | DThunderbird Lake Fisherman'S | Cleveland | D | No recent samples |
| 4 | DThunderbird Lake Hog Creek | Cleveland | D | No recent samples |
| 5 | DLake Sardis Clayton | Pushmataha | D | No recent samples |
| 6 | DLake Nahni Waiya Tuskahomma | Pushmataha | D | No recent samples |
| 7 | DPioneer Cover Lake | Osage | D | No recent samples |
| 8 | DOsage Cove Lake | Osage | D | No recent samples |
| 9 | DCoon Creek Lake | Kay | D | No recent samples |
| 10 | DSandy Beach Lake | Osage | D | No recent samples |
| 11 | DWashunga Bay Lake | Kay | D | No recent samples |
| 12 | DWewoka Lake | Seminole | D | 2.5 ft |
| 13 | DSportsman Lake | Seminole | D | 6.2 ft |
| 14 | DEucha Lake | Delaware | D | 3.1 ft |
| 15 | DCopan Lake | Washington | D | 1.6 ft |
| 16 | DSpavinaw Lake | Mayes | D | 3.3 ft |
| 17 | DWes Watkins Reservoir | Pottawatomie | D | 1.8 ft |
| 18 | DLake Konawa | Seminole | D | 3.1 ft |
| 19 | DGreenleaf Lake | Muskogee | D | 2.5 ft |
| 20 | DGrand Lake | Delaware | D | 1.6 ft |
| 21 | DLake Thunderbird | Cleveland | D | 1.7 ft |
| 22 | DLake Texoma | Bryan | D | 3.2 ft |
| 23 | DLake Texoma | Marshall | D | 1.7 ft |
| 24 | CSarge Creek Lake | Kay | C | No recent samples |
| 25 | CLake Texoma | Grayson | C | 4.2 ft |
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
The top-graded lake in every state we cover, picked grade-first with water clarity as the tie-breaker — plus the states whose winner is still not clean.
State-by-state Secchi champions: the clearest measured lake in each U.S. state we grade, which is not the same as the cleanest nutrient grade.
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.