Oregon reservoir · state assessment record
Upper Klamath Lake
Assessment decisions reported by Oregon to EPA under Clean Water Act sections 303(d) and 305(b), last assessed in the 2024 reporting cycle.
- 62,130
- Assessed acres
- Lake / Reservoir / Pond
- Water type
- 4,139.9 ft
- Water Surface Elevation (provisional)
This waterbody in one line
Upper Klamath Lake, a reservoir in Oregon, is assessed as not supporting one or more designated uses, with 7 listed impairment causes in the state's most recent Integrated Report cycle (2024). 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 (7 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. A USGS gauge tracks its water surface elevation daily.
- Not Supporting
- overall status
- P100
- Assessed size nationally
- P1
- 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 Upper Klamath Lake'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
The number that most separates Upper Klamath Lake nationally is assessed size: 62,130 acres, larger than 100% of the 38,628 lake-type units with an area on file.
Longer than most cause lists
7 listed causes puts this unit above 99% 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, 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.
Upper Klamath Lake: Category 5, TMDL still owed
Category 5 is the Integrated Report band where a TMDL (or equivalent) is still expected for Upper Klamath 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 Upper Klamath 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, Oregon carries 1,431 filed lake-type waterbodies in the August 2026 extract, and this page renders the assessment record EPA assigned to Upper Klamath 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.
| Designated use | Group | Verdict |
|---|---|---|
| Aesthetic Quality | Other | Not Supporting |
| Fish and Aquatic Life | Aquatic-life or related | Not Supporting |
| Fishing | Fish-consumption or fishery | Not Supporting |
| Livestock Watering | Other | Not Supporting |
| Private Domestic Water Supply | Drinking-water supply designation | Not Supporting |
| Public Domestic Water Supply | Drinking-water supply designation | Not Supporting |
| Water Contact Recreation | Recreation | Not Supporting |
| Boating | Recreation | Not Assessed |
| Industrial Water Supply | Other | Not Assessed |
| Irrigation | Other | Not Assessed |
| 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 |
|---|---|---|---|
| Dissolved Oxygen | Fish and Aquatic Life | 2002 | TMDL approved |
| pH | Fish and Aquatic Life | 2002 | TMDL approved |
| Chlorophyll-a | Aesthetic Quality | 2004 | TMDL approved |
| Harmful Algal Blooms | Water Contact Recreation, Fishing, Private Domestic Water Supply, Livestock Watering, Public Domestic Water Supply | 2010 | TMDL approved |
| Sediment | Fish and Aquatic Life | 2010 | TMDL priority: Low |
| Methylmercury | Fishing, Private Domestic Water Supply, Public Domestic Water Supply | 2018 | TMDL priority: Low |
| Temperature | Fish and Aquatic Life | 2022 | TMDL priority: Low |
Reading the record
Where Upper Klamath Lake sits among peers
46% of Oregon's lakes assessed this deeply also had no use supported
Oregon ruled definitively on 7 designated uses at Upper Klamath Lake and found none of them supported. The dataset shows 68 Oregon lakes judged to that same depth.
Oregon's assessed lakes are most often judged on 5 or more uses, as this one was.
Computed share from EPA ATTAINS filed records, not an official EPA rating or safety grade.
| 1 | 2 | 3 | 4 | 5+ | |
|---|---|---|---|---|---|
| All supported | 4 | 2 | 6 | 2 | 0 |
| Mixed | Not possible | 4 | 3 | 0 | 37 |
| None supported | 43 | 18 | 10 | 19 | 31 (this record) |
Ringed cell: Upper Klamath Lake. Source: EPA ATTAINS, Reporting cycles 1987–2026.
Scale and rank
Upper Klamath Lake 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 62,130 assessed acres it ranks 45th 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 44 lakes with a larger one.
Water level
A USGS gauge tracks this reservoir's water surface elevation daily, and the latest reading is 0.82 ft below the reading 30 days earlier, against a 365-day observed range of 3.4 ft.
Water level: 365-day record
Daily water surface elevation values, feet above the United States Bureau of Reclamation Klamath Basin Datum, a zero set for this project rather than sea level, from USGS gauge 11505800 (Upper Klamath Lake at Rocky Point, or), shown weekly. Readings are daily-batch snapshots, not real-time conditions.
- Latest reading
- 4,139.9 ft 0.819999999999709ft vs 30 days earlier
- 2026-08-15 · Provisional, subject to USGS revision
Water level: 365-day record
Subscribe to water level updates for Upper Klamath Lake (RSS)
USGS files this series under its water surface elevation parameter, but the reading sits far below the 35 ft land-surface altitude USGS records for the gauge itself, which is how the local zero was identified. The figure tracks this reservoir’s own stage and is comparable with its own history alone, never with another lake’s reading.
Every daily value in this window is provisional and subject to USGS revision: USGS has not yet approved any value in the trailing 365 days of this record.
USGS operates 6 monitoring sites carrying this lake’s name; this record reads site 11505800, the densest of the 4 reporting daily values. The others are 11505900, 11507000, 11507001, 421830121512600, 421935121551200. Each site measures against its own zero, so their readings are not interchangeable.
USGS monitoring locations on this lake: 11505800 (read here), 11505900, 11507000, 11507001, 421830121512600, 421935121551200
In context
Where Upper Klamath 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
62,130 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
7 Longer than most more listed causes than 99% 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 Upper Klamath Lake. 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, Upper Klamath Lake ranks 5th by listed-cause count (7 listed causes) and 2nd by assessed size among the 167 with an area filed; it sits in the not-supporting set (165 statewide) . Its listed causes include Dissolved Oxygen, Chlorophyll-a, Harmful Algal Blooms, Methylmercury, and Temperature, which also appear among Oregon's most-filed impairment causes (led by Temperature). It also lists pH and Sediment, 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 |
| Columbia River Not Supporting | 55,630 |
| Lake Abert Not Assessed | 44,751 |
| Summer Lake Not reported | 31,606 |
| Harney Lake Not reported | 31,369 |
Peers near Upper Klamath Lake's size or cause load
Similar assessed acres
Nearest filed extents (62,130 acres here).
- Goose Lake (Modoc County) · 62,385 acres · CA
- Lake Okeechobee · 59,818 acres · FL
- Lake of the Ozarks · 59,520 acres · MO
- Kenai Lake · 57,618 acres · AK
Similar cause load
Nearest listed-cause counts (7 here). Peers already in the acreage column are omitted.
- Adder Pond · 7 causes · NH
- Arrow Lake · 7 causes · TN
- Barton Cove · 7 causes · MA
- Blue Heron Lagoon · 7 causes · MI
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
- 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 OR_LK_1801020303_05_100375. 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.