Idaho lake · state assessment record
Upper Twin Lakes
The assessment record reported by Idaho to EPA under Clean Water Act sections 303(d) and 305(b).
- 525
- Assessed acres
- Lake, Freshwater
- Water type
This waterbody in one line
Upper Twin Lakes, a lake in Idaho, has no overall assessment verdict in the state's most recent Integrated Report. By assessed acreage it sits among the largest 10% by assessed acreage nationally (38,628 lakes).
- Not reported
- overall status
- P91
- Assessed size nationally
Assessment verdicts are the state agency's decisions as reported to EPA ATTAINS; PlainLakes renders them without modification.
Upper Twin Lakes against the ATTAINS 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 Upper Twin Lakes nationally is assessed size: 525.2 acres, larger than 91% of the 38,628 lake-type units with an area on file.
According to the U.S. Environmental Protection Agency's ATTAINS program, Idaho carries 630 filed lake-type waterbodies in the August 2026 extract, and this page renders the assessment record EPA assigned to Upper Twin Lakes without modification. See our methodology for reporting-unit limits and gauge linking rules.
The record
Listed impairment causes
No causes are listed because this lake has no overall assessment verdict in the reported cycle. An unassessed waterbody is neither confirmed clean nor confirmed impaired.
Reading the record
What Upper Twin Lakes's record holds
Scale and rank
Upper Twin Lakes is one of 630 lake-type waterbodies reported to EPA from Idaho. It is not among the 186 whose reported record carries enough populated assessment or gauge data for this site to list and index it. At 525 assessed acres it ranks 3,610th 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 3,609 lakes with a larger one.
Which uses were judged
Idaho filed no use-level rows for this lake and reached no overall verdict, so nothing here was judged either way.
What this record holds
Idaho filed no overall verdict, no reporting cycle and no EPA category for this lake, so the record holds the identifying fields above and no judgement of any kind: no verdict, and 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.
In context
Where Upper Twin Lakes 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
525 Top 9% larger than 91% 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 Upper Twin Lakes. Hover or tap any bar for its full count and share.
In context
Idaho context
ATTAINS carries 630 lake-type waterbodies in Idaho, 51 assessed as not supporting at least one use and 198 fully supporting.
| Other large assessed lakes in Idaho | Assessed acres |
|---|---|
| Pend Oreille Lake Not Supporting | 80,829 |
| Bear Lake Not Assessed | 34,454 |
| American Falls Reservoir (Snake River) Not Supporting | 31,724 |
| Cascade Reservoir Not Supporting | 25,040 |
| American Falls Reservoir (Snake River) Tribal Waters Not Assessed | 23,785 |
| Grays Lake Not Assessed | 23,678 |
Lakes near Upper Twin Lakes's assessed acres
Similar assessed acres
Nearest filed extents (525 acres here).
- Barnes Lake · 525 acres · ND
- Stephen a. Forbes · 525 acres · IL
- Crystal Lake · 525 acres · WI
- TOXAWAY RIVER (Lake Toxaway) · 525 acres · NC
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 ID17010305PN013L_01L. 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.