Alaska lake · state assessment record
Big Lake
Assessment decisions reported by Alaska to EPA under Clean Water Act sections 303(d) and 305(b), last assessed in the 2006 reporting cycle.
- 1,250
- Assessed acres
- Lake, Freshwater
- Water type
This waterbody in one line
Big Lake, a lake in Alaska, is assessed as not supporting one or more designated uses, with one listed impairment cause in the state's most recent Integrated Report cycle (2006). By assessed acreage it sits among the largest 5% by assessed acreage nationally (38,628 lakes); its impairment list is among the longest nationally (one listed cause vs 23,610 assessed lakes). Aquatic life is assessed as not supporting.
- Not Supporting
- overall status
- P95
- Assessed size nationally
- P20
- Shorter cause list
- Not Supporting
- aquatic life
Assessment verdicts are the state agency'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.
Reading Big Lake's filed record
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 Big Lake nationally is assessed size: 1,250 acres, larger than 95% of the 38,628 lake-type units with an area on file.
Every ruled-on use is not supporting
On the uses this filer ruled on, recreation, aquatic life, every determination is Not Supporting. That is a use-by-use reading of the filed record, not a single overall lake grade.
Big Lake: Category 4A reading
Category 4A means a TMDL (or equivalent) is already approved for the impairment on Big Lake. The remaining work is implementation and tracking, read the cleanup-standing and cause rows for what the state already committed to address.
Overall status: not supporting
The filer's overall status for Big Lake 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, Alaska carries 77 filed lake-type waterbodies in the August 2026 extract, and this page renders the assessment record EPA assigned to Big Lake 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 state's definitive verdicts; other entries mean the use was not conclusively assessed in this cycle. Alaska filed its own confidence on the 7 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 |
|---|---|---|
| Fresh Water / Growth and Propagation of Fish, Shellfish, Other Aquatic Life and Wildlife | Aquatic-life or related | Not Supporting Filer confidence: Good |
| Fresh Water / Water Recreation / Contact Recreation | Recreation | Not Supporting Filer confidence: Good |
| Fresh Water / Water Recreation / Secondary Recreation | Recreation | Not Supporting Filer confidence: Good |
| Fresh Water / Water Supply / Agriculture, Including Irrigation and Stock Watering | Other | Not Supporting Filer confidence: Good |
| Fresh Water / Water Supply / Aquaculture | Other | Not Supporting Filer confidence: Good |
| Fresh Water / Water Supply / Drinking, Culinary, and Food Processing | Drinking-water supply designation | Not Supporting Filer confidence: Good |
| Fresh Water / Water Supply / Industrial | Other | Not Supporting Filer confidence: Good |
The record
Listed impairment causes
Causes the state 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 |
|---|---|---|---|
| Petroleum Hydrocarbons | Fresh Water / Water Recreation / Secondary Recreation; Fresh Water / Growth and Propagation of Fish, Shellfish, Other Aquatic Life and Wildlife; Fresh Water / Water Recreation / Contact Recreation; Fresh Water / Water Supply / Agriculture, Including Irrigation and Stock Watering; Fresh Water / Water Supply / Aquaculture; Fresh Water / Water Supply / Industrial; Fresh Water / Water Supply / Drinking, Culinary, and Food Processing | 2008 | TMDL approved |
Probable sources named by the state
Each source below is listed under the cause the state filed it against, and carries the word the state filed with it — confirmed, or suspected.
- Petroleum Hydrocarbons
- Other Recreational Pollution Sources (confirmed)
Reading the record
Big Lake: Category 4A reading
4A Category 4A: impaired, TMDL completed
Alaska filed this assessment unit as Category 4A: impaired, with a pollutant-budget TMDL already completed under 303(d). The listing remains an impairment finding; the plan is on file rather than still awaiting write-up.
Scale and rank
Big Lake is one of 77 lake-type waterbodies reported to EPA from Alaska, and one of 12 whose reported record carries enough populated assessment or gauge data for this site to list and index it. At 1,250 assessed acres it ranks 1,938th 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 1,937 lakes with a larger one.
Still unfiled
The state 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
Alaska 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 Big Lake 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
1,250 Top 5% larger than 95% 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 Big Lake. Hover or tap any bar for its full count and share.
In context
Alaska context
ATTAINS carries 77 lake-type waterbodies in Alaska, 7 assessed as not supporting at least one use and 9 fully supporting. Among the 12 indexed units there, Big Lake ranks 3rd by listed-cause count (one listed cause) and 1st by assessed size among the 12 with an area filed; it sits in the not-supporting set (7 statewide) . Its listed causes (Petroleum Hydrocarbons) sit outside Alaska's top-five list, which is led by Fecal Coliform.
| Other large assessed lakes in Alaska | Assessed acres |
|---|---|
| Iliamna Lake Not Assessed | 960,000 |
| Kenai Lake Not Assessed | 57,618 |
| Whitefish Lake Not Assessed | 18,726 |
| Lower Fire Lake Not Assessed | 4,480 |
| Redoubt Lake Not Assessed | 3,209 |
| Harding Lake Fully Supporting | 2,659 |
Peers near Big Lake's size or cause load
Similar assessed acres
Nearest filed extents (1,250 acres here).
- Bagaduce River · 1,250 acres · ME
- Occoquan Reservoir · 1,250 acres · VA
- Lake Owen · 1,250 acres · WI
- Thunder · 1,250 acres · MN
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 state's reported decisions for assessment unit AK_L_2040105_008_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.