Oregon reservoir · state assessment record
McGuire Reservoir
Assessment decisions reported by Oregon to EPA under Clean Water Act sections 303(d) and 305(b), last assessed in the 2002 reporting cycle.
- 136
- Assessed acres
- Lake / Reservoir / Pond
- Water type
This waterbody in one line
McGuire Reservoir, a reservoir in Oregon, is assessed as not supporting one or more designated uses, with 3 listed impairment causes in the state's most recent Integrated Report cycle (2002). By assessed acreage it sits in the upper quartile by assessed acreage nationally (38,628 lakes); its impairment list is among the longest nationally (3 listed causes vs 23,610 assessed lakes). Aquatic life is assessed as not supporting.
- Not Supporting
- overall status
- P76
- Assessed size nationally
- P5
- 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 McGuire Reservoir 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: cause-list length
The standout filed fact is cause-list length: 3 listed impairment causes, a longer list than 90% of assessed lake-type units (n=23,610). List length tracks how states sample and code, not a severity score.
Every filed use falls short
On the uses this filer ruled on, aquatic life, every determination is Not Supporting. That is a use-by-use reading of the filed record, not a single overall lake grade.
McGuire Reservoir: Category 4A reading
Category 4A means a TMDL (or equivalent) is already approved for the impairment on McGuire Reservoir. The remaining work is implementation and tracking, read the cleanup-standing and cause rows for what the state already committed to address.
Overall status: not supporting
The filer's overall status for McGuire Reservoir is Not Supporting. That tile summarizes the assessment unit; the designated-use rows and cause list are the evidence behind it.
Large assessed unit
At 136.4 acres, McGuire Reservoir clears the upper tercile of assessed lake-type units with an area on file (9,494 still larger). Size comparisons use the portal's deduplicated lake ranking population, not raw ATTAINS row counts.
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 McGuire 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 |
|---|---|---|
| Fish and Aquatic Life | Aquatic-life or related | Not Supporting |
| Aesthetic Quality | Other | Not Assessed |
| Boating | Recreation | Not Assessed |
| Fishing | Fish-consumption or fishery | Not Assessed |
| Industrial Water Supply | Other | Not Assessed |
| Irrigation | Other | Not Assessed |
| Livestock Watering | Other | Not Assessed |
| Private Domestic Water Supply | Drinking-water supply designation | Not Assessed |
| Public Domestic Water Supply | Drinking-water supply designation | Not Assessed |
| Water Contact Recreation | Recreation | 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 |
|---|---|---|---|
| Habitat Alterations | Fish and Aquatic Life | 2002 | TMDL priority: Low |
| Sediment | Fish and Aquatic Life | 2002 | Action recorded (type not published) |
| Temperature | Fish and Aquatic Life | 2002 | Action recorded (type not published) |
Reading the record
McGuire Reservoir: Category 4A reading
4A Category 4A: impaired, TMDL completed
Oregon filed this assessment unit as Category 4A: impaired, with a pollutant-budget TMDL already completed under 303(d). The listing remains an impairment finding; the plan is on file rather than still awaiting write-up.
Scale and rank
McGuire Reservoir 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 136 assessed acres it ranks 9,495th 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 9,494 lakes with a larger one.
Awaiting a filing
The state has not yet filed a definitive fish-consumption verdict and a definitive recreation verdict for this record; those fields populate when it reports them in a future Integrated Report cycle.
In context
Where McGuire 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
136 Top 24% larger than 76% 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
3 Longer than most more listed causes than 90% 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 McGuire Reservoir. 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, McGuire Reservoir ranks 56th by listed-cause count (3 listed causes) and 114th by assessed size among the 167 with an area filed; it sits in the not-supporting set (165 statewide) . Its listed causes include Temperature, which also appears among Oregon's most-filed impairment causes (led by Temperature). It also lists Habitat Alterations 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 |
| 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 McGuire Reservoir's size or cause load
Similar assessed acres
Nearest filed extents (136 acres here).
- Loon · 136 acres · MN
- Irving Pond · 136 acres · NY
- Point Lake · 136 acres · WI
- Strand · 136 acres · MN
Similar cause load
Nearest listed-cause counts (3 here). Peers already in the acreage column are omitted.
- 67th St. Beach · 3 causes · IL
- Abiquiu Reservoir · 3 causes · NM
- Absecon Creek (AC Reserviors) (gage to SB) · 3 causes · NJ
- Absecon Creek (below gage) · 3 causes · NJ
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 OR_LK_1710020302_05_100157. 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.