Idaho lake · state assessment record
Coeur d’Alene Lake
Assessment decisions reported by Idaho to EPA under Clean Water Act sections 303(d) and 305(b), last assessed in the 2020 reporting cycle.
- 22,977
- Assessed acres
- Lake, Freshwater
- Water type
- 27.6 ft
- Gage Height (provisional)
This waterbody in one line
Coeur d’Alene Lake, a lake in Idaho, is assessed as not supporting one or more designated uses, with 4 listed impairment causes in the state's most recent Integrated Report cycle (2020). By assessed acreage it sits among the largest 1% of assessed lakes nationally (38,628 lakes with a filed area); its impairment list is among the longest nationally (4 listed causes vs 23,610 assessed lakes). Aquatic life is assessed as not supporting. A USGS gauge tracks its gage height daily.
- Not Supporting
- overall status
- P100
- Assessed size nationally
- P3
- 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.
How Coeur d’Alene Lake reads against 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: assessed size
The number that most separates Coeur d’Alene Lake nationally is assessed size: 22,977 acres, larger than 100% of the 38,628 lake-type units with an area on file.
Longer than most cause lists
4 listed causes puts this unit above 95% of assessed lake-type records by list length. Treat that as a coding-and-sampling signal: states that split pollutants finely mint longer lists without proving worse water.
Every filed use falls short
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.
Coeur d’Alene Lake: Category 5, TMDL still owed
Category 5 is the Integrated Report band where a TMDL (or equivalent) is still expected for Coeur d’Alene Lake. Read the listed causes and any cleanup actions filed beside them before treating the overall status tile as a finished restoration story.
Overall status: not supporting
The filer's overall status for Coeur d’Alene Lake is Not Supporting. That tile summarizes the assessment unit; the designated-use rows and cause list are the evidence behind it.
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 Coeur d’Alene 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. Monitoring behind at least one of these designated-use verdicts ran through 2016, as Idaho filed it. For the definitive verdicts on this record, Idaho filed the assessment basis as Monitored Data. Those are EPA's own words, not PlainLakes' summary of them. Idaho filed its own confidence on the 2 definitive verdicts it rated: Good and Excellent. 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 |
|---|---|---|
| Cold Water Aquatic Life | Aquatic-life or related | Not Supporting Filer confidence: Good |
| Primary Contact Recreation | Recreation | Not Supporting Filer confidence: Excellent |
| Salmonid Spawning | Aquatic-life or related | Not Supporting |
| Aesthetic | Other | Not Assessed |
| Agricultural Water Supply | Other | Not Assessed |
| Domestic Water Supply | Drinking-water supply designation | Not Assessed |
| Industrial Water Supply | Other | Not Assessed |
| Wildlife Habitat | Other | 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 and the Clean Water Act action recorded against it.
| Cause | Affected uses | First listed | Cleanup standing |
|---|---|---|---|
| Cadmium | Cold Water Aquatic Life | 2006 | TMDL priority: Low |
| Lead | Cold Water Aquatic Life | 2006 | TMDL priority: Low |
| Zinc | Cold Water Aquatic Life | 2006 | TMDL priority: Low |
| Mercury | Primary Contact Recreation, Salmonid Spawning, Cold Water Aquatic Life | 2020 | TMDL priority: Low |
Reading the record
Where Coeur d’Alene Lake sits among peers
5 of 16 Idaho lakes assessed this deeply also had no use supported
Idaho ruled definitively on 3 designated uses at Coeur d’Alene Lake and found none of them supported. The dataset shows 16 Idaho lakes judged to that same depth.
Idaho's assessed lakes are most often judged on 5 or more uses; this one was judged on 3.
| 1 | 2 | 3 | 4 | 5+ | |
|---|---|---|---|---|---|
| All supported | 6 | 25 | 8 | 12 | 147 |
| Mixed | Not possible | 7 | 3 | 0 | 0 |
| None supported | 17 | 19 | 5 (this record) | 0 | 0 |
Ringed cell: Coeur d’Alene Lake. Source: EPA ATTAINS, Reporting cycles 1987–2026.
Scale and rank
Coeur d’Alene Lake is one of 630 lake-type waterbodies reported to EPA from Idaho, and one of 186 whose reported record carries enough populated assessment or gauge data for this site to list and index it. At 22,977 assessed acres it ranks 139th 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 138 lakes with a larger one.
Water level
A USGS gauge tracks this lake's gage height daily, and the latest reading is 0.34 ft below the reading 30 days earlier, against a 365-day observed range of 6.3 ft. 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.
Water level: 365-day record
Daily gage height values, feet above this gauge’s own local zero, not above sea level, from USGS gauge 12415500 (Coeur D Alene Lake at Coeur D Alene Id), shown weekly. Readings are daily-batch snapshots, not real-time conditions. Each daily value is a single reading taken at 24:00, not a daily mean. It is the only daily statistic USGS files for this gauge.
- Latest reading
- 27.6 ft 0.33999999999999986ft vs 30 days earlier
- 2026-08-15 · Provisional, subject to USGS revision
Water level: 365-day record
Subscribe to water level updates for Coeur d’Alene Lake (RSS)
76 of the 365 daily values in this window (21%) are provisional and subject to USGS revision; USGS has approved this gauge's record through 2026-05-31.
Full gauge record: USGS monitoring location 12415500
In context
Where Coeur d’Alene 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
22,977 Top 1% larger than 99%+ 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
4 Longer than most more listed causes than 95% 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 Coeur d’Alene Lake. 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. Among the 186 indexed units there, Coeur d’Alene Lake ranks 6th by listed-cause count (4 listed causes) and 4th by assessed size among the 186 with an area filed; it sits in the not-supporting set (51 statewide) . Its listed causes include Mercury, which also appears among Idaho's most-filed impairment causes (led by Phosphorus, Total). It also lists Cadmium, Lead, and Zinc, outside that top-five list.
| 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 |
Peers near Coeur d’Alene Lake's size or cause load
Similar assessed acres
Nearest filed extents (22,977 acres here).
- Petenwell Lake · 23,001 acres · WI
- Center Hill Reservoir · 23,051 acres · TN
- Norris Reservoir · 23,198 acres · TN
- Little Missouri Bay (Lake Sakakawea) · 22,719 acres · ND
Similar cause load
Nearest listed-cause counts (4 here). Peers already in the acreage column are omitted.
- Agency Lake · 4 causes · OR
- Alachua Sink · 4 causes · FL
- Aldrich Pond · 4 causes · MA
- Anderson & Carlton · 4 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
- Water levels shown are daily snapshots. Seasonal drawdown and datum conventions matter when comparing levels. How to read level data
- 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 ID17010303PN001L_0L. 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.