Montana lake · state assessment record
Halfpint Reservoir
The assessment record reported by Montana to EPA under Clean Water Act sections 303(d) and 305(b), filed in the 2014 reporting cycle.
- 30
- Assessed acres
- Lake, Freshwater
- Water type
This waterbody in one line
Halfpint Reservoir, a lake in Montana, was reported but not assessed in the state's most recent Integrated Report cycle (2014). By assessed acreage it sits below the national median by assessed acreage (38,628 lakes).
- Not Assessed
- overall status
- P43
- Assessed size nationally
Assessment verdicts are the state agency's decisions as reported to EPA ATTAINS; PlainLakes renders them without modification.
Reading Halfpint Reservoir'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: 30.4 acres sits near the middle of the 38,628 units with an area filed (percentile 43).
IR category 3 on Halfpint Reservoir
The Integrated Report category filed for Halfpint Reservoir is 3. PlainLakes renders EPA's code without remapping it into a consumer grade.
Overall status: Not Assessed
ATTAINS overall status on this unit is “Not Assessed”. PlainLakes does not rewrite that vocabulary into a consumer score.
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 Halfpint Reservoir 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.
| Designated use | Group | Verdict |
|---|---|---|
| Agricultural | Other | Not Assessed |
| Aquatic Life | Aquatic-life or related | Not Assessed |
| Drinking Water | Drinking-water supply designation | Not Assessed |
| Primary Contact Recreation | Recreation | Not Assessed |
The record
Listed impairment causes
The state reported this lake in its 2014 Integrated Report cycle but reached no assessment determination, so no causes are listed. The unit is recorded under EPA integrated-reporting Category 3: reviewed, with insufficient information to determine whether it meets water-quality standards. An undetermined waterbody is neither confirmed clean nor confirmed impaired.
Reading the record
What Halfpint Reservoir's record holds
Scale and rank
Halfpint Reservoir is one of 73 lake-type waterbodies reported to EPA from Montana. It is not among the 52 whose reported record carries enough populated assessment or gauge data for this site to list and index it. At 30 assessed acres it ranks 22,169th 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 22,168 lakes with a larger one.
What this record holds
Montana filed this lake in its 2014 Integrated Report cycle but reached no determination, so the record holds that filing and its use rows, but no verdict, and with nothing judged, no impairment cause to track over time. The state has not yet filed a definitive fish-consumption verdict, a definitive recreation verdict, a definitive aquatic-life verdict, and 1 other 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 Halfpint Reservoir 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
30 Top 57% larger than 43% 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
In both charts each bar is a band and taller bars hold more waterbodies; the dashed line and filled bar mark Halfpint Reservoir. 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.
| 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 |
Lakes near Halfpint Reservoir's assessed acres
Similar assessed acres
Nearest filed extents (30 acres here).
- Lake Warn · 30 acres · NY
- Round · 30 acres · MN
- Bear Hill Pond · 30 acres · NH
- Davis Reservoir · 30 acres · ID
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 MT40O002_032. 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.