Some of these decisions are EPA's. 1 of these 340 records carry at least one designated-use verdict or impairment listing EPA filed rather than North Dakota; on those, the determination is EPA's rather than North Dakota's. They are counted in every figure on this page, and each record page names which.
State water-quality picture · #25 by reported lake-type waterbodies
North Dakota lakes and reservoirs
Every figure on this page is computed from the assessment decisions North Dakota reported to the U.S. Environmental Protection Agency under Clean Water Act sections 303(d) and 305(b) (reporting cycles 2008–2022), plus daily water-level observations from the U.S. Geological Survey.
- 340
- Reported waterbodies
- 52
- Not supporting a use
- 4
- Fish use not supporting
- 4
- Gauged lakes
North Dakota in one line
340 lake-type waterbodies in North Dakota are reported to EPA ATTAINS across reporting cycles 2008–2022: 52 assessed as not supporting at least one designated use, 143 fully supporting, and 145 without a definitive overall verdict. The most-listed impairment cause is Nutrients, on 44 waterbodies.
- 340
- reported waterbodies
- 52
- not supporting a use
- 143
- fully supporting
- 30%
- of definitive verdicts impaired
An unassessed waterbody is neither confirmed clean nor confirmed impaired; states assess on multi-year cycles. 19 of those 143 fully supporting verdicts (13%) rest on designated uses this site does not report (irrigation, navigation and industrial water supply), with North Dakota recording no verdict on fish consumption, recreation, aquatic life and drinking water. They are counted above because the state filed them, and excluded from the impaired share below because that figure compares states.
North Dakota's mid-size register with a lighter not-supporting share
North Dakota sits in the middle third by inventory size (340 units) and in the lowest third for ruled not-supporting share (30%).
Data updated 2026-08-17
According to the U.S. Environmental Protection Agency's ATTAINS program, North Dakota reported 340 lake-type waterbodies in North Dakota in the August 2026 extract. See our methodology for filer attribution and multi-year reporting cycles.
Overall-status mix on North Dakota's mid-size inventory
Every reported lake-type unit in North Dakota falls into exactly one overall-status bucket. This bar is the inventory partition; the cause chart and national gauge below answer different questions.
Most-listed impairment causes in North Dakota
Waterbodies carrying each listed cause, most first
- Nutrients
Nutrients
44 waterbodies
- Dissolved Oxygen
Dissolved Oxygen
27 waterbodies
- Sedimentation/Siltation 12
Sedimentation/Siltation
12 waterbodies
- Methylmercury 4
Methylmercury
4 waterbodies
- Eutrophication, Nutrients 2
Eutrophication, Nutrients
2 waterbodies
What this shows Nutrients is the most-listed impairment cause in North Dakota, on 44 of the lake-type waterbodies reported there.
Computed share from EPA ATTAINS filed records, not an official EPA rating or safety grade.
North Dakota: 30% of ruled verdicts are not-supporting, against a national share of 53%, 1.8× below the national rate.
Reporting practice
Where North Dakota stands on definitive-verdict coverage
Each reporting authority decides how much of the water it files to EPA it actually assesses in a cycle. That decision sets the denominator behind every count on this page.
North Dakota holds the 25th-largest reported lake-type inventory in the country, 340 assessment units, carrying a definitive verdict on 51.8% of it. The counts above describe the 176 units carrying a verdict, not all 340 reported. North Dakota has also retired 10 lake-type assessment units, superseded filings that are kept on the site but not counted here.
The states reporting at the nearest rates are North Carolina (50.8%) and Michigan (54.3%).
Assessing more of an inventory is a reporting choice, set by cycle length, monitoring budget and how finely a state splits its waters into units. It is not a measure of water quality, and it is why a raw count from one state does not sit beside a raw count from another. How assessment coverage varies.
North Dakota against every comparable state
Share of reported lake-type waterbodies carrying a definitive verdict
51.8% 32nd of 47 higher than 15 of 47 states
the 47 comparable states, by definitive-verdict share
Each bar is a band; taller bars hold more states. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Source EPA ATTAINS · Reporting cycles 1987–2026
Each bar counts states whose definitive-verdict share falls in that 10-point band. The 47 states shown are those reporting at least 25 lake-type units; a share off a smaller inventory is precision the data does not have.
By size
Largest assessed lakes in North Dakota
By assessed acreage as reported in ATTAINS. Acreage is the assessed unit's size, which can differ from a lake's full surface area.
| # | Waterbody | Assessed acres |
|---|---|---|
| 1 | Lake Sakakawea Not Supporting | 318,821 |
| 2 | Devils Lake Not Supporting | 102,385 |
| 3 | Lake Oahe Fully Supporting | 68,123 |
| 4 | Little Missouri Bay (Lake Sakakawea) Not Supporting | 22,719 |
| 5 | Long Lake Refuge Not reported | 16,990 |
| 6 | Lake Audubon Fully Supporting | 16,610 |
| 7 | Pelican Lake Not reported | 13,491 |
| 8 | West Stump Lake Not reported | 12,962 |
| 9 | Lake Darling Not Supporting | 8,698 |
| 10 | Horsehead Lake Fully Supporting | 6,778 |
| 11 | Alkaline Lake Fully Supporting | 5,434 |
| 12 | Dry Lake Not reported | 5,432 |
By cause count
Most-listed waterbodies in North Dakota
Waterbodies carrying the most listed impairment causes among the lake-type units reported by North Dakota.
| # | Waterbody | Listed causes |
|---|---|---|
| 1 | Beaver Lake Not Supporting | 3 |
| 1 | Braddock Lake Not Supporting | 3 |
| 1 | Brewer Lake Not Supporting | 3 |
| 1 | Crown Butte Dam Not Supporting | 3 |
| 1 | Danzig Dam Not Supporting | 3 |
| 1 | McVille Dam Not Supporting | 3 |
| 1 | Patterson Lake Not Supporting | 3 |
| 1 | Powers Lake Not Supporting | 3 |
| 1 | Warsing Dam Not Supporting | 3 |
| 10 | Armourdale Dam Not Supporting | 2 |
9 of the 10 rows in this table tie on the ranked value: 9 at 3 (rank 1). Tied rows share a rank and are listed in no meaningful order; where a tie reaches the top the medal is shared, because nothing separates those rows.
Gauge network
Lakes with a daily level record in North Dakota
Lakes with a linked USGS gauge and a daily water-level record. Readings are daily-batch snapshots, not real-time.
States near North Dakota's lighter not-supporting load
Two EPA ATTAINS peer sets outside North Dakota. The reporting-practice chart above stays on definitive-verdict share; these neighborhoods highlight register-size and not-supporting peers while North Dakota's ruled impairment share sits in the lowest third.
Similar reported inventory
Nearest states by lake-type units on the register (340 here).
States with a similar not-supporting load
Nearest states by units assessed not supporting a use (52 here). Inventory peers above are omitted.
- Idaho · 51 not supporting · 1 off
- Georgia · 47 not supporting · 5 off
- New Mexico · 46 not supporting · 6 off
- Tennessee · 60 not supporting · 8 off
Peers are nearest-neighbor matches on EPA ATTAINS register size and not-supporting counts among states with at least 25 reported units. Impairment peers skip states already listed in the inventory column so the two link sets stay distinct.
Using this state picture
- Comparisons across states hold on shares, not counts: 51.8% of the inventory reported from North Dakota carries a definitive verdict, 32nd of 47 comparable states. National rankings
- Fish-consumption verdicts here are assessment decisions. Species-level meal advice comes from the state fish-advisory program. Consumption guide
- Browse every named North Dakota waterbody with a populated record. Browse waterbodies
PlainLakes renders state assessment decisions and federal gauge observations without modification.
Figures on this page are computed from the assessment decisions North Dakota reported to EPA's ATTAINS system and from USGS National Water Information System daily values, no number is typed in by an editor. State counts aggregate every lake-type assessment unit reported by North Dakota, including unnamed units that never receive their own page. 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.