Montana lake · state assessment record
Lamesteer National Wildlife Refuge
Assessment decisions reported by Montana to EPA under Clean Water Act sections 303(d) and 305(b), last assessed in the 2000 reporting cycle.
- 74
- Assessed acres
- Lake, Freshwater
- Water type
This waterbody in one line
Lamesteer National Wildlife Refuge, a lake in Montana, is assessed as not supporting one or more designated uses, with one listed impairment cause in the state's most recent Integrated Report cycle (2000). By assessed acreage it sits above the national median by assessed acreage (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
- P63
- 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 Lamesteer National Wildlife Refuge'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
Assessed size is not the extreme here: 73.6 acres sits near the middle of the 38,628 units with an area filed (percentile 63).
Every filed use falls short
On the uses this filer ruled on, aquatic life, every determination is Not Supporting. That is a use-by-use reading of the filed record, not a single overall lake grade.
Lamesteer National Wildlife Refuge: Category 4C reading
Category 4C marks impairment from pollution that is not a pollutant (for example habitat or flow alteration) on Lamesteer National Wildlife Refuge. A classic TMDL load model often does not apply; the cause list should name the non-pollutant stressor.
Overall status: not supporting
The filer's overall status for Lamesteer National Wildlife Refuge 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, Montana carries 73 filed lake-type waterbodies in the August 2026 extract, and this page renders the assessment record EPA assigned to Lamesteer National Wildlife Refuge 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. For the one definitive verdict on this record, Montana filed the assessment basis as Monitored & Extrapolated Data. Those are EPA's own words, not PlainLakes' summary of them; where a verdict is filed as extrapolated, the state did not reach it from monitoring alone.
| Designated use | Group | Verdict |
|---|---|---|
| Aquatic Life | Aquatic-life or related | Not Supporting |
| Primary Contact Recreation | Recreation | Not Assessed |
The record
Listed impairment causes
Causes the state listed as impairing designated uses of this lake, with the cycle each was first listed. None is a pollutant, so none carries a TMDL cleanup plan.
| Cause | Affected uses | First listed | Cleanup standing |
|---|---|---|---|
| Cause Unknown | Aquatic Life | Not reported | Not applicable (non-pollutant); filed TMDL priority Low |
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.
- Cause Unknown
- Agriculture (suspected)
Reading the record
Lamesteer National Wildlife Refuge: Category 4C reading
4C Category 4C: impaired by a non-pollutant; TMDL programme does not apply
Montana filed this assessment unit as Category 4C: the impairment is not caused by a pollutant, so the Clean Water Act 303(d) cleanup-plan (TMDL) programme, which allocates pollutant loads, does not apply here.
A 4C listing is still an impairment finding about designated uses; it is not a clean bill of health. How listing and cleanup work.
Scale and rank
Lamesteer National Wildlife Refuge is one of 73 lake-type waterbodies reported to EPA from Montana, and one of 52 whose reported record carries enough populated assessment or gauge data for this site to list and index it. At 74 assessed acres it ranks 14,210th 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 14,209 lakes with a larger one.
Still unfiled
The state has not yet filed a definitive fish-consumption verdict and a definitive recreation verdict for this record; those fields populate when it reports them in a future Integrated Report cycle.
Reported trophic class
Montana 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 Lamesteer National Wildlife Refuge 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
74 Top 37% larger than 63% 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 Lamesteer National Wildlife Refuge. Hover or tap any bar for its full count and share.
In context
Montana context
ATTAINS carries 73 lake-type waterbodies in Montana, 28 assessed as not supporting at least one use and 28 fully supporting. Among the 52 indexed units there, Lamesteer National Wildlife Refuge ranks 28th by listed-cause count (one listed cause) and 47th by assessed size among the 52 with an area filed; it sits in the not-supporting set (28 statewide) . Its listed causes (Cause Unknown) sit outside Montana's top-five list, which is led by Flow Regime Modification.
| Other large assessed lakes in Montana | Assessed acres |
|---|---|
| Fort Peck Reservoir Not Supporting | 233,296 |
| Flathead Lake Not Supporting | 57,305 |
| Canyon Ferry Reservoir Not Supporting | 32,810 |
| Lake Koocanusa Not Supporting | 28,875 |
| Hungry Horse Reservoir Fully Supporting | 23,596 |
| Lake Elwell (Tiber Reservoir) Fully Supporting | 15,041 |
Peers near Lamesteer National Wildlife Refuge's size or cause load
Similar assessed acres
Nearest filed extents (74 acres here).
- East Annalaide · 74 acres · MN
- Fish Creek Pond, West · 74 acres · NY
- German · 74 acres · MN
- Gimiwan · 74 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 MT39G002_010. 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.