Oklahoma lake · tribal assessment record
Lake Nahni Waiya Site 1
Assessment decisions reported by The Choctaw Nation of Oklahoma to EPA under Clean Water Act sections 303(d) and 305(b), last assessed in the 2022 reporting cycle.
- 104
- Assessed acres
- Lake
- Water type
This waterbody in one line
Lake Nahni Waiya Site 1, a lake in Oklahoma, is assessed as not supporting one or more designated uses, with 2 listed impairment causes in the Choctaw Nation of Oklahoma's most recent Integrated Report cycle (2022). By assessed acreage it sits above the national median by assessed acreage (38,628 lakes); its impairment list is among the longest nationally (2 listed causes vs 23,610 assessed lakes). Aquatic life is assessed as not supporting.
- Not Supporting
- overall status
- P71
- Assessed size nationally
- P10
- Shorter cause list
- Not Supporting
- aquatic life
Assessment verdicts are the Choctaw Nation of Oklahoma'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.
Where Lake Nahni Waiya Site 1 stands in 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: cause-list length
The standout filed fact is cause-list length: 2 listed impairment causes, a longer list than 80% of assessed lake-type units (n=23,610). List length tracks how states sample and code, not a severity score.
Not one verdict, several
This record splits: Not Supporting on aquatic life, Fully Supporting on recreation. The divergence is inside the designated-use matrix, not a single all-or-nothing label.
Overall status: not supporting
The filer's overall status for Lake Nahni Waiya Site 1 is Not Supporting. That tile summarizes the assessment unit; the designated-use rows and cause list are the evidence behind it.
Small within Oklahoma
State size rank 153 of 170 puts Lake Nahni Waiya Site 1 toward the small end of Oklahoma's indexed lake-type units with an area.
Large assessed unit
At 104 acres, Lake Nahni Waiya Site 1 clears the upper tercile of assessed lake-type units with an area on file (11,413 still larger). Size comparisons use the portal's deduplicated lake ranking population, not raw ATTAINS row counts.
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 Nahni Waiya Site 1 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 Choctaw Nation of Oklahoma's definitive verdicts; other entries mean the use was not conclusively assessed in this cycle. The latest monitoring the Choctaw Nation of Oklahoma filed against this record runs through 2023. For the definitive verdicts on this record, the Choctaw Nation of Oklahoma filed the assessment basis as Monitored Data. Those are EPA's own words, not PlainLakes' summary of them. the Choctaw Nation of Oklahoma filed its own confidence on the 2 definitive verdicts it rated: Good. That rating is the filer's, in EPA's own field, and EPA publishes no definition of the four words it offers.
| Designated use | Group | Verdict |
|---|---|---|
| Primary Body Contact Recreation | Recreation | Fully Supporting Filer confidence: Good |
| Warm Water Aquatic Community | Aquatic-life or related | Not Supporting Filer confidence: Good |
| General | Other | Insufficient Information Filer confidence: Good |
The record
Listed impairment causes
Causes the Choctaw Nation of Oklahoma 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 |
|---|---|---|---|
| pH | Warm Water Aquatic Community | 2021 | None reported |
| Dissolved Oxygen | Warm Water Aquatic Community | 2022 | None reported |
Reading the record
Where Lake Nahni Waiya Site 1 sits among peers
6 of 14 Oklahoma lakes assessed this deeply also came out mixed
The Choctaw Nation of Oklahoma ruled definitively on 2 designated uses at Lake Nahni Waiya Site 1 and found 1 of 2 not supported. The dataset shows 14 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 2.
| 1 | 2 | 3 | 4 | 5+ | |
|---|---|---|---|---|---|
| All supported | 13 | 8 | 7 | 8 | 9 |
| Mixed | Not possible | 6 (this record) | 12 | 30 | 92 |
| None supported | 13 | 0 | 0 | 0 | 0 |
Ringed cell: Lake Nahni Waiya Site 1. Source: EPA ATTAINS, Reporting cycles 1987–2026.
Scale and rank
Lake Nahni Waiya Site 1 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 104 assessed acres it ranks 11,414th 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 11,413 lakes with a larger one.
Still unfiled
The Choctaw Nation of Oklahoma 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.
Reported trophic class
The Choctaw Nation of Oklahoma carried the trophic field for this assessment unit and filed it as unclassified, which records that no class was determined rather than that the water is unenriched. What the trophic scale measures.
In context
Where Lake Nahni Waiya Site 1 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
104 Top 29% larger than 71% 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
2 Longer than most more listed causes than 80% 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 Nahni Waiya Site 1. 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 Nahni Waiya Site 1 ranks 91st by listed-cause count (2 listed causes) and 153rd by assessed size among the 170 with an area filed; it sits in the not-supporting set (153 statewide) . Its listed causes include pH and Dissolved Oxygen, which also appear among Oklahoma's most-filed impairment causes (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 Nahni Waiya Site 1's size or cause load
Similar assessed acres
Nearest filed extents (104 acres here).
- Echo (Plymth) · 104 acres · VT
- Edna · 104 acres · MN
- Gull Pond · 104 acres · MA
- Hy-Crest Pond · 104 acres · MA
Similar cause load
Nearest listed-cause counts (2 here). Peers already in the acreage column are omitted.
- 12th St. Beach · 2 causes · IL
- 31st St. Beach · 2 causes · IL
- 49th St. Beach · 2 causes · IL
- 57th St. Beach · 2 causes · IL
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 Choctaw Nation of Oklahoma's reported decisions for assessment unit LNW-001. 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.