Oklahoma lake · tribal assessment record
Lake Tenkiller
Assessment decisions reported by Cherokee Nation to EPA under Clean Water Act sections 303(d) and 305(b), last assessed in the 2021 reporting cycle.
- 12,900
- Assessed acres
- Lake
- Water type
This waterbody in one line
Lake Tenkiller, a lake in Oklahoma, is assessed as not supporting one or more designated uses, with one listed impairment cause in the Cherokee Nation's most recent Integrated Report cycle (2021). By assessed acreage it sits among the largest 1% of assessed lakes nationally (38,628 lakes with a filed area); its impairment list is among the longest nationally (one listed cause vs 23,610 assessed lakes). Aquatic life is assessed as fully supporting.
- Not Supporting
- overall status
- P99
- Assessed size nationally
- P20
- Shorter cause list
- Fully Supporting
- aquatic life
Assessment verdicts are the Cherokee Nation's decisions as reported to EPA ATTAINS; PlainLakes renders them without modification.
A composite of this record's EPA ATTAINS designated-use verdicts, filed impairment count, and assessment currency, weighted and benchmarked against the national corpus of assessed active waterbodies. This is a water-quality standing, not a human-recreation or property-value judgment, and dimensions with no filed verdict drop out rather than count against the score.
How Lake Tenkiller reads against the filed register
Paragraphs are selected by this unit's percentiles and use matrix: different lakes lead with different dimensions. Figures are ATTAINS / portal register arithmetic, not advice.
The signature stat: assessed size
The number that most separates Lake Tenkiller nationally is assessed size: 12,900 acres, larger than 99% of the 38,628 lake-type units with an area on file.
Every filed use clears the bar
The filed use determinations for recreation, aquatic life are all Fully Supporting. Where an overall IR category still flags the unit, look at the cause list and report standing rather than treating the use row as empty.
Overall status: not supporting
The filer's overall status for Lake Tenkiller is Not Supporting. That tile summarizes the assessment unit; the designated-use rows and cause list are the evidence behind it.
Typical cause-list length
1 listed cause is a middle-tercile list length among assessed lake-type units. Look to IR category and use outcomes for the distinctive reading.
According to the U.S. Environmental Protection Agency's ATTAINS program, Oklahoma carries 456 filed lake-type waterbodies in the August 2026 extract, and this page renders the assessment record EPA assigned to Lake Tenkiller without modification. See our methodology for reporting-unit limits and gauge linking rules.
The record
Designated-use assessments
Fully Supporting and Not Supporting are the Cherokee Nation's definitive verdicts; other entries mean the use was not conclusively assessed in this cycle. The latest monitoring the Cherokee Nation filed against this record runs through 2021. For the definitive verdicts on this record, the Cherokee Nation filed the assessment basis as Monitored Data. Those are EPA's own words, not PlainLakes' summary of them.
| Designated use | Group | Verdict |
|---|---|---|
| Aesthetics | Other | Not Supporting |
| Agriculture | Other | Fully Supporting |
| Primary Body Contact Recreation | Recreation | Fully Supporting |
| Warm Water Aquatic Community | Aquatic-life or related | Fully Supporting |
The record
Listed impairment causes
Causes the Cherokee Nation listed as impairing designated uses of this lake, with the cycle each was first listed and the Clean Water Act action recorded against it.
| Cause | Affected uses | First listed | Cleanup standing |
|---|---|---|---|
| Phosphorus, Total | Aesthetics | 2021 | None reported |
Probable sources named by the Cherokee Nation
Each source below is listed under the cause the Cherokee Nation filed it against, and carries the word the Cherokee Nation filed with it — confirmed, or suspected.
- Phosphorus, Total
- Unknown Point Source (suspected)
Reading the record
Where Lake Tenkiller sits among peers
79% of Oklahoma's lakes assessed this deeply also came out mixed
The Cherokee Nation ruled definitively on 4 designated uses at Lake Tenkiller and found 1 of 4 not supported. The dataset shows 38 Oklahoma lakes judged to that same depth.
Oklahoma's assessed lakes are most often judged on 5 or more uses; this one was judged on 4.
Computed share from EPA ATTAINS filed records, not an official EPA rating or safety grade.
| 1 | 2 | 3 | 4 | 5+ | |
|---|---|---|---|---|---|
| All supported | 13 | 8 | 7 | 8 | 9 |
| Mixed | Not possible | 6 | 12 | 30 (this record) | 92 |
| None supported | 13 | 0 | 0 | 0 | 0 |
Ringed cell: Lake Tenkiller. Source: EPA ATTAINS, Reporting cycles 1987–2026.
Scale and rank
Lake Tenkiller is one of 456 lake-type waterbodies reported to EPA from Oklahoma, and one of 173 whose reported record carries enough populated assessment or gauge data for this site to list and index it. At 12,900 assessed acres it ranks 249th by assessed size among the 38,628 lakes the dataset carries an area for, counting a state’s repeated filings of one water once, behind 248 lakes with a larger one.
Awaiting a filing
The Cherokee Nation has not yet filed a definitive fish-consumption verdict for this record; that field populates when it reports it in a future Integrated Report cycle.
In context
Where Lake Tenkiller sits nationally
Assessed size among U.S. lakes
Distribution of assessed acreage across ATTAINS lakes filed with an area, counting a state’s repeated filings of one water once
12,900 Top 1% larger than 99% of 38,628 lakes
lakes the dataset carries an area for, counting a state’s repeated filings of one water once, bucketed by value
Source EPA ATTAINS · Reporting cycles 1987–2026
Listed causes vs waterbodies carrying a verdict
How many impairment causes U.S. waterbodies with a reported verdict carry
1 Longer than most more listed causes than 49% of 23,610 waterbodies carrying a verdict
named waterbodies carrying a verdict, bucketed by value
Source EPA ATTAINS · Reporting cycles 1987–2026
In both charts each bar is a band and taller bars hold more waterbodies; the dashed line and filled bar mark Lake Tenkiller. Hover or tap any bar for its full count and share.
In context
Oklahoma context
ATTAINS carries 456 lake-type waterbodies in Oklahoma, 153 assessed as not supporting at least one use and 45 fully supporting. Among the 173 indexed units there, Lake Tenkiller ranks 103rd by listed-cause count (one listed cause) and 20th by assessed size among the 170 with an area filed; it sits in the not-supporting set (153 statewide) . Its listed causes (Phosphorus, Total) sit outside Oklahoma's top-five list, which is led by Mercury.
| Other large assessed lakes in Oklahoma | Assessed acres |
|---|---|
| Grand Lake Site 12 Not Supporting | 46,500 |
| Grand Lake Site 13 Not Supporting | 46,500 |
| Grand Lake Site 14 Fully Supporting | 46,500 |
| Grand Lake Site 15 Fully Supporting | 46,500 |
| Robert S. Kerr Lake Not Supporting | 43,380 |
| Texoma Lake, Red River Arm, Lower Not Supporting | 31,081 |
Peers near Lake Tenkiller's size or cause load
Similar assessed acres
Nearest filed extents (12,900 acres here).
- Greers Ferry Lake · 12,883 acres · AR
- Turtle Flambeau Flowage · 12,943 acres · WI
- West Stump Lake · 12,962 acres · ND
- San Luis Reservoir · 12,970 acres · CA
Similar cause load
Nearest listed-cause counts (1 here). Peers already in the acreage column are omitted.
- Aaron · 1 causes · MN
- Aaron River Reservoir · 1 causes · MA
- Abbotts Creek (including Lexington-Thomasville Water Supply Reservoir at normal reservoir elevation, Tom-A-Lex Lake) · 1 causes · NC
- Abeniki Lake · 1 causes · NH
What to do with this record
- Assessment verdicts are cycle-based, not real-time. For fish-consumption decisions, your state advisory program is the binding source. Consumption status guide
- Impairment listings follow the Clean Water Act 303(d) process; a listing is a regulatory finding, not a closure notice. 303(d) explained
PlainLakes renders state assessment decisions and federal gauge observations without modification. It does not issue advisories.
Assessment decisions on this page are rendered directly from state Integrated Report records in EPA's ATTAINS system; gauge figures are daily-value observations from the USGS National Water Information System, no number is typed in by an editor. Overall status, use verdicts, and causes are the Cherokee Nation's reported decisions for assessment unit LTK. Counts and percentiles are computed across all lake-type records PlainLakes ingests from ATTAINS. 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.