Oregon reservoir · state assessment record
Columbia River (2,108 acres)
Assessment decisions reported by Oregon to EPA under Clean Water Act sections 303(d) and 305(b), last assessed in the 2020 reporting cycle. The cleanup plan below was established by EPA rather than by Oregon.
- 2,108
- Assessed acres
- Lake / Reservoir / Pond
- Water type
This waterbody in one line
Columbia River, a reservoir in Oregon, 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 5% by assessed acreage nationally (38,628 lakes); its impairment list is among the longest nationally (4 listed causes vs 23,610 assessed lakes). Aquatic life is assessed as not supporting. Oregon assesses fishing as not supported; it reported no verdict on fish consumption itself.
- Not Supporting
- overall status
- P97
- 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.
Columbia River 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 Columbia River nationally is assessed size: 2,108 acres, larger than 97% 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 ruled-on use is not supporting
On the uses this filer ruled on, fish consumption, aquatic life, every determination is Not Supporting. That is a use-by-use reading of the filed record, not a single overall lake grade.
Columbia River: Category 5, TMDL still owed
Category 5 is the Integrated Report band where a TMDL (or equivalent) is still expected for Columbia River. 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 Columbia River 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, Oregon carries 1,431 filed lake-type waterbodies in the August 2026 extract, and this page renders the assessment record EPA assigned to Columbia River 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 |
|---|---|---|
| Fish and Aquatic Life | Aquatic-life or related | Not Supporting |
| Fishing | Fish-consumption or fishery | Not Supporting |
| Private Domestic Water Supply | Drinking-water supply designation | Not Supporting |
| Public Domestic Water Supply | Drinking-water supply designation | Not Supporting |
| Aesthetic Quality | Other | Insufficient Information |
| Boating | Recreation | Not Assessed |
| Commercial Navigation and Transportation | Other | Not Assessed |
| Hydropower | Other | Not Assessed |
| Industrial Water Supply | Other | Not Assessed |
| Irrigation | Other | Not Assessed |
| Livestock Watering | Other | Not Assessed |
| Water Contact Recreation | Recreation | Insufficient Information |
| Wildlife and Hunting | Other | Not Assessed |
The record
Listed impairment causes
Causes the state listed as impairing designated uses of this reservoir, with the cycle each was first listed and the Clean Water Act action recorded against it.
| Cause | Affected uses | First listed | Cleanup standing |
|---|---|---|---|
| Dioxin | Fishing, Private Domestic Water Supply, Public Domestic Water Supply | 1998 | Action recorded (type not published) |
| Total Dissolved Gas | Fish and Aquatic Life | 2002 | Action recorded (type not published) |
| Temperature | Fish and Aquatic Life | 2004 | TMDL established by EPA |
| Methylmercury | Fishing, Private Domestic Water Supply, Public Domestic Water Supply | 2018 | TMDL priority: Low |
Reading the record
EPA plan standing on Columbia River
1 cleanup plan EPA established here
EPA, not Oregon, established that plan.
Scale and rank
Columbia River is one of 1,431 lake-type waterbodies reported to EPA from Oregon, and one of 167 whose reported record carries enough populated assessment or gauge data for this site to list and index it. At 2,108 assessed acres it ranks 1,315th 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 1,314 lakes with a larger one.
Awaiting a filing
The state has not yet filed a definitive recreation verdict for this record; that field populates when it reports it in a future Integrated Report cycle.
In context
Where Columbia River 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
2,108 Top 3% larger than 97% 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 Columbia River. Hover or tap any bar for its full count and share.
In context
Oregon context
ATTAINS carries 1,431 lake-type waterbodies in Oregon, 165 assessed as not supporting at least one use and 14 fully supporting. Among the 167 indexed units there, Columbia River ranks 33rd by listed-cause count (4 listed causes) and 48th by assessed size among the 167 with an area filed; it sits in the not-supporting set (165 statewide) . Its listed causes include Temperature and Methylmercury, which also appear among Oregon's most-filed impairment causes (led by Temperature). It also lists Dioxin and Total Dissolved Gas, outside that top-five list.
| Other large assessed lakes in Oregon | Assessed acres |
|---|---|
| Goose Lake Not reported | 93,152 |
| Malheur Slough Not Supporting | 73,544 |
| Upper Klamath Lake Not Supporting | 62,130 |
| Columbia River Not Supporting | 55,630 |
| Lake Abert Not Assessed | 44,751 |
| Summer Lake Not reported | 31,606 |
Peers near Columbia River's size or cause load
Similar assessed acres
Nearest filed extents (2,108 acres here).
- Swan (Main Basin) · 2,108 acres · MN
- Horseshoe (Madison) · 2,107 acres · IL
- Island Lake · 2,109 acres · ND
- Great Falls Reservoir · 2,109 acres · TN
Similar cause load
Nearest listed-cause counts (4 here). Peers already in the acreage column are omitted.
- Alachua Sink · 4 causes · FL
- Aldrich Pond · 4 causes · MA
- American Falls Reservoir (Snake River) · 4 causes · ID
- Anderson & Carlton · 4 causes · IL
What to do with this record
- The listing here is on a fishery use, not on fish consumption, and this state reported no consumption verdict for this reservoir. Your state fish-advisory program is the source for whether the catch is safe to eat. 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 OR_LK_1707010102_88_100150. 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.