North Dakota reservoir · state assessment record
McGregor Dam
Assessment decisions reported by North Dakota to EPA under Clean Water Act sections 303(d) and 305(b), last assessed in the 2016 reporting cycle.
- 58
- Assessed acres
- Reservoir
- Water type
- Eutrophic
- Reported trophic class
This waterbody in one line
McGregor Dam, a reservoir in North Dakota, is assessed as not supporting one or more designated uses, with one listed impairment cause in the state's most recent Integrated Report cycle (2016). By assessed acreage it sits above the national median by assessed acreage (38,628 lakes); its impairment list is among the longest nationally (one listed cause vs 23,610 assessed lakes). Aquatic life is assessed as fully supporting, and flagged threatened: currently met, but on a trajectory the state expects to fail.
- Not Supporting
- overall status
- P58
- Assessed size nationally
- P20
- Shorter cause list
- Fully Supporting
- aquatic life, threatened
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 McGregor Dam'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: in-state cause rank
Inside North Dakota, cause-list rank 50 of 174 is mid-pack, the state peer table is not driven by an extreme list length here.
McGregor Dam: Category 4A reading
Category 4A means a TMDL (or equivalent) is already approved for the impairment on McGregor Dam. The remaining work is implementation and tracking, read the cleanup-standing and cause rows for what the state already committed to address.
Every ruled-on use is fully supporting
The filed use determinations for recreation, aquatic life are all Fully Supporting. Where an overall IR category still flags the unit, look at the cause list and report standing rather than treating the use row as empty.
Overall status: not supporting
The filer's overall status for McGregor Dam is Not Supporting. That tile summarizes the assessment unit; the designated-use rows and cause list are the evidence behind it.
Mid-pack inside North Dakota
Size rank 125 of 174 inside North Dakota is mid-pack; the national percentile is the better scale comparison for this unit.
According to the U.S. Environmental Protection Agency's ATTAINS program, North Dakota carries 340 filed lake-type waterbodies in the August 2026 extract, and this page renders the assessment record EPA assigned to McGregor Dam 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. North Dakota filed its own confidence on the 4 definitive verdicts it rated: Good. 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 |
|---|---|---|
| Agricultural | Other | Fully Supporting Filer confidence: Good |
| Fish and Other Aquatic Biota threatened | Aquatic-life or related | Fully Supporting Filer confidence: Good |
| Industrial | Other | Fully Supporting Filer confidence: Good |
| Recreation threatened | Recreation | Fully Supporting Filer confidence: Good |
| Fish Consumption | Fish-consumption or fishery | Not Assessed |
| Municipal and Domestic | Drinking-water supply designation | 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 |
|---|---|---|---|
| Nutrients | Fish and Other Aquatic Biota; Recreation | 1992 | TMDL approved |
Reading the record
McGregor Dam: Category 4A reading
4A Category 4A: impaired, TMDL completed
North Dakota 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
McGregor Dam is one of 340 lake-type waterbodies reported to EPA from North Dakota, and one of 174 whose reported record carries enough populated assessment or gauge data for this site to list and index it. At 58 assessed acres it ranks 16,278th 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 16,277 lakes with a larger one.
Still unfiled
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.
Reported trophic class
Eutrophic is the trophic class the filing agency reported to EPA ATTAINS for this assessment unit. It describes nutrient enrichment, not whether the water is safe, and it is not a PlainLakes inference. What the trophic scale measures.
In context
Where McGregor Dam 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
58 Top 42% larger than 58% 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
1 Longer than most more listed causes than 49% 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 McGregor Dam. Hover or tap any bar for its full count and share.
In context
North Dakota context
ATTAINS carries 340 lake-type waterbodies in North Dakota, 52 assessed as not supporting at least one use and 143 fully supporting. Among the 174 indexed units there, McGregor Dam ranks 50th by listed-cause count (one listed cause) and 125th by assessed size among the 174 with an area filed; it sits in the not-supporting set (52 statewide) . Its listed causes include Nutrients, which also appears among North Dakota's most-filed impairment causes (led by Nutrients).
| Other large assessed lakes in North Dakota | Assessed acres |
|---|---|
| Lake Sakakawea Not Supporting | 318,821 |
| Devils Lake Not Supporting | 102,385 |
| Lake Oahe Fully Supporting | 68,123 |
| Little Missouri Bay (Lake Sakakawea) Not Supporting | 22,719 |
| Long Lake Refuge Not reported | 16,990 |
| Lake Audubon Fully Supporting | 16,610 |
Peers near McGregor Dam's size or cause load
Similar assessed acres
Nearest filed extents (58 acres here).
- Lake Superior · 58 acres · WI
- Tamarack · 58 acres · MN
- Little · 58 acres · MN
- Chinaman · 58 acres · MN
Similar cause load
Nearest listed-cause counts (1 here). Peers already in the acreage column are omitted.
- Aaron · 1 causes · MN
- Aaron River Reservoir · 1 causes · MA
- Abbotts Creek (including Lexington-Thomasville Water Supply Reservoir at normal reservoir elevation, Tom-A-Lex Lake) · 1 causes · NC
- Abeniki Lake · 1 causes · NH
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 ND-10110101-019-L_00. 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.