State water-quality picture · #21 by reported lake-type waterbodies
Oklahoma lakes and reservoirs
Every figure on this page is computed from the assessment decisions Oklahoma and 7 tribal nations reported to the U.S. Environmental Protection Agency under Clean Water Act sections 303(d) and 305(b) (reporting cycles 1987–2025), plus daily water-level observations from the U.S. Geological Survey.
- 456
- Reported waterbodies
- 153
- Not supporting a use
- 95
- Fish use not supporting
- 5
- Gauged lakes
Oklahoma in one line
456 lake-type waterbodies in Oklahoma are reported to EPA ATTAINS across reporting cycles 1987–2025: 153 assessed as not supporting at least one designated use, 45 fully supporting, and 258 without a definitive overall verdict. The most-listed impairment cause is Mercury, on 87 waterbodies.
- 456
- reported waterbodies
- 153
- not supporting a use
- 45
- fully supporting
- 78%
- of definitive verdicts impaired
An unassessed waterbody is neither confirmed clean nor confirmed impaired; states assess on multi-year cycles. 3 of those 45 fully supporting verdicts (7%) rest on designated uses this site does not report (irrigation, navigation and industrial water supply), with Oklahoma recording no verdict on fish consumption, recreation, aquatic life and drinking water. They are counted above because the state filed them, and excluded from the impaired share below because that figure compares states.
Oklahoma's mid-size register with a heavier not-supporting share
Oklahoma sits in the middle third by inventory size (456 units) and in the upper third for ruled not-supporting share (78%).
Data updated 2026-08-17
According to the U.S. Environmental Protection Agency's ATTAINS program, Oklahoma and 7 tribal nations reported 456 lake-type waterbodies in Oklahoma in the August 2026 extract. See our methodology for filer attribution and multi-year reporting cycles.
Overall-status mix on Oklahoma's mid-size inventory
Every reported lake-type unit in Oklahoma falls into exactly one overall-status bucket. This bar is the inventory partition; the cause chart and national gauge below answer different questions.
Most-listed impairment causes in Oklahoma
Waterbodies carrying each listed cause, most first
- Mercury
Mercury
87 waterbodies
- Turbidity
Turbidity
74 waterbodies
- Chlorophyll-a
Chlorophyll-a
45 waterbodies
- Dissolved Oxygen 32
Dissolved Oxygen
32 waterbodies
- pH 15
pH
15 waterbodies
What this shows Mercury is the most-listed impairment cause in Oklahoma, on 87 of the lake-type waterbodies reported there.
Computed share from EPA ATTAINS filed records, not an official EPA rating or safety grade.
Oklahoma: 78% of ruled verdicts are not-supporting, against a national share of 53%, 1.5× the national rate.
Reporting practice
How much of the Oklahoma inventory carries a definitive verdict
Each reporting authority decides how much of the water it files to EPA it actually assesses in a cycle. That decision sets the denominator behind every count on this page.
Oklahoma holds the 21st-largest reported lake-type inventory in the country, 456 assessment units, carrying a definitive verdict on 42.8% of it. The counts above describe the 195 units carrying a verdict, not all 456 reported. Oklahoma has also retired 4 lake-type assessment units, superseded filings that are kept on the site but not counted here.
The states reporting at the nearest rates are Missouri (42.9%) and New Mexico (42%).
Assessing more of an inventory is a reporting choice, set by cycle length, monitoring budget and how finely a state splits its waters into units. It is not a measure of water quality, and it is why a raw count from one state does not sit beside a raw count from another. How assessment coverage varies.
Not every unit counted here was assessed by Oklahoma. 28 of them were filed by 7 sovereign tribal nations reporting directly to EPA under Clean Water Act section 518, which lets a tribe set and apply its own water quality standards in the same manner as a state: Choctaw Nation of Oklahoma (12), Cherokee Nation (4), Seneca-Cayuga Nation (4), Chickasaw Nation (3), Citizen Potawatomi Nation (3), Caddo Nation of Oklahoma (1), Sac & Fox Nation (1). Those decisions are theirs, not Oklahoma's.
Oklahoma against every comparable state
Share of reported lake-type waterbodies carrying a definitive verdict
42.8% 37th of 47 higher than 10 of 47 states
the 47 comparable states, by definitive-verdict share
Each bar is a band; taller bars hold more states. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Source EPA ATTAINS · Reporting cycles 1987–2026
Each bar counts states whose definitive-verdict share falls in that 10-point band. The 47 states shown are those reporting at least 25 lake-type units; a share off a smaller inventory is precision the data does not have.
By size
Largest assessed lakes in Oklahoma
By assessed acreage as reported in ATTAINS. Acreage is the assessed unit's size, which can differ from a lake's full surface area.
| # | Waterbody | Assessed acres |
|---|---|---|
| 1 | Grand Lake Site 12 Not Supporting | 46,500 |
| 1 | Grand Lake Site 13 Not Supporting | 46,500 |
| 1 | Grand Lake Site 14 Fully Supporting | 46,500 |
| 1 | Grand Lake Site 15 Fully Supporting | 46,500 |
| 5 | Robert S. Kerr Lake Not Supporting | 43,380 |
| 6 | Texoma Lake, Red River Arm, Lower Not Supporting | 31,081 |
| 7 | Oologah Lake Not Supporting | 29,460 |
| 8 | Eufaula Lake, Gaines Creek Arm Not Supporting | 24,990 |
| 9 | Eufaula Lake, N. Canadian River Arm Not Supporting | 20,680 |
| 10 | Grand Lake O' the Cherokees, Middle Not Supporting | 19,584 |
| 11 | Texoma Lake, Washita River Arm, Lower Not Supporting | 19,214 |
| 12 | Eufaula Lake, Canadian River Arm Not Supporting | 19,040 |
4 of the 12 rows in this table tie on the ranked value: 4 at 46,500 (rank 1). Tied rows share a rank and are listed in no meaningful order; where a tie reaches the top the medal is shared, because nothing separates those rows.
By cause count
Most-listed waterbodies in Oklahoma
Waterbodies carrying the most listed impairment causes among the lake-type units reported by Oklahoma and by 7 tribal nations.
| # | Waterbody | Listed causes |
|---|---|---|
| 1 | Coalgate Municipal Lake Not Supporting | 5 |
| 1 | Wister Lake Not Supporting | 5 |
| 3 | Atoka Lake Not Supporting | 4 |
| 3 | Broken Bow Lake Not Supporting | 4 |
| 3 | Heyburn Lake Not Supporting | 4 |
| 3 | Holdenville Lake Not Supporting | 4 |
| 3 | Pine Creek Lake Not Supporting | 4 |
| 3 | Thunderbird Lake Not Supporting | 4 |
| 9 | Arbuckle Lake (Lake of the Arbuckles) Not Supporting | 3 |
| 9 | Birch Lake Not Supporting | 3 |
Every row in this table ties with at least one other on the ranked value: 2 at 5 (rank 1), 6 at 4 (rank 3), 2 at 3 (rank 9). Tied rows share a rank and are listed in no meaningful order; where a tie reaches the top the medal is shared, because nothing separates those rows.
Gauge network
Lakes with a daily level record in Oklahoma
Lakes with a linked USGS gauge and a daily water-level record. Readings are daily-batch snapshots, not real-time.
- Lake Hudson Not Supporting USGS gauge 07191400 Level record →
- Lake Texoma Not Supporting USGS gauge 07331455 Level record →
- Stanley Draper Lake Not Supporting USGS gauge 07229445 Level record →
- Spavinaw Lake Not Supporting USGS gauge 07191300 Level record →
- Wes Watkins Reservoir Not Supporting USGS gauge 07241588 Level record →
States near Oklahoma's heavier not-supporting load
Two EPA ATTAINS peer sets outside Oklahoma. The reporting-practice chart above stays on definitive-verdict share; the neighborhoods below emphasize cross-state nearest neighbors when the not-supporting count is in the upper third.
Similar reported inventory
Nearest states by lake-type units on the register (456 here).
- West Virginia · 434 units · 22 off
- Texas · 489 units · 33 off
- Pennsylvania · 516 units · 60 off
- Iowa · 371 units · 85 off
Comparable not-supporting counts
Nearest states by units assessed not supporting a use (153 here). Inventory peers above are omitted.
- Vermont · 154 not supporting · 1 off
- Missouri · 151 not supporting · 2 off
- Indiana · 145 not supporting · 8 off
- South Dakota · 145 not supporting · 8 off
Peers are nearest-neighbor matches on EPA ATTAINS register size and not-supporting counts among states with at least 25 reported units. Impairment peers skip states already listed in the inventory column so the two link sets stay distinct.
Using this state picture
- Comparisons across states hold on shares, not counts: 42.8% of the inventory reported from Oklahoma carries a definitive verdict, 37th of 47 comparable states. National rankings
- Fish-consumption verdicts here are assessment decisions. Species-level meal advice comes from the state fish-advisory program. Consumption guide
- Browse every named Oklahoma waterbody with a populated record. Browse waterbodies
PlainLakes renders state assessment decisions and federal gauge observations without modification.
Figures on this page are computed from the assessment decisions Oklahoma and 7 tribal nations reported to EPA's ATTAINS system and from USGS National Water Information System daily values, no number is typed in by an editor. State counts aggregate every lake-type assessment unit reported by Oklahoma and by 7 tribal nations, including unnamed units that never receive their own page. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2026-08-17. Primary sources: EPA ATTAINS and USGS National Water Information System.