State water-quality picture · #32 by reported lake-type waterbodies
South Dakota lakes and reservoirs
Every figure on this page is computed from the assessment decisions South Dakota reported to the U.S. Environmental Protection Agency under Clean Water Act sections 303(d) and 305(b) (reporting cycles 2012–2026), plus daily water-level observations from the U.S. Geological Survey.
- 195
- Reported waterbodies
- 145
- Not supporting a use
- Not reported
- Fish use assessments
- 1
- Gauged lake
South Dakota in one line
195 lake-type waterbodies in South Dakota are reported to EPA ATTAINS across reporting cycles 2012–2026: 145 assessed as not supporting at least one designated use, 41 fully supporting, and 9 without a definitive overall verdict. The most-listed impairment cause is Mercury in Fish Tissue, on 75 waterbodies.
- 195
- reported waterbodies
- 145
- not supporting a use
- 41
- fully supporting
- 78%
- of definitive verdicts impaired
An unassessed waterbody is neither confirmed clean nor confirmed impaired; states assess on multi-year cycles.
South Dakota's mid-size register with a heavier not-supporting share
South Dakota sits in the middle third by inventory size (195 units) and in the upper third for ruled not-supporting share (78%).
Data updated 2026-08-17
According to the U.S. Environmental Protection Agency's ATTAINS program, South Dakota reported 195 lake-type waterbodies in South Dakota in the August 2026 extract. See our methodology for filer attribution and multi-year reporting cycles.
Overall-status mix on South Dakota's mid-size inventory
Every reported lake-type unit in South 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 South Dakota
Waterbodies carrying each listed cause, most first
- Mercury in Fish Tissue
Mercury in Fish Tissue
75 waterbodies
- pH
pH
35 waterbodies
- Chlorophyll-a
Chlorophyll-a
32 waterbodies
- Dissolved Oxygen 27
Dissolved Oxygen
27 waterbodies
- Escherichia coli (E. coli) 23
Escherichia coli (E. coli)
23 waterbodies
What this shows Mercury in Fish Tissue is the most-listed impairment cause in South Dakota, on 75 of the lake-type waterbodies reported there.
Computed share from EPA ATTAINS filed records, not an official EPA rating or safety grade.
South Dakota: 78% of ruled verdicts are not-supporting, against a national share of 53%, 1.5× the national rate.
Reporting practice
A definitive verdict covers nearly all of South Dakota's inventory
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.
South Dakota holds the 32nd-largest reported lake-type inventory in the country, 195 assessment units, carrying a definitive verdict on 95.4% of it. The counts above describe the 186 units carrying a verdict, not all 195 reported. South Dakota has also retired 3 lake-type assessment units, superseded filings that are kept on the site but not counted here.
The states reporting at the nearest rates are Georgia (95.2%) and Kansas (96.3%).
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.
South Dakota against every comparable state
Share of reported lake-type waterbodies carrying a definitive verdict
95.4% 8th of 47 higher than 39 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 South 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 Thompson Not Supporting | 13,888 |
| 2 | Lake Poinsett Not Supporting | 9,795 |
| 3 | Waubay Lake Not Supporting | 9,531 |
| 4 | Bitter Lake Not Supporting | 7,865 |
| 5 | Dry Lake Number 2 Not Supporting | 6,442 |
| 6 | Orman Dam (Belle Fourche Reservoir) Not Supporting | 6,106 |
| 7 | Big Stone Lake Fully Supporting | 5,800 |
| 8 | Shadehill Reservoir Not Supporting | 5,160 |
| 9 | Lake Traverse Fully Supporting | 5,082 |
| 10 | Lake Kampeska Fully Supporting | 5,067 |
| 11 | Lake Andes Not Supporting | 4,756 |
| 12 | Angostura Reservoir Fully Supporting | 4,753 |
By cause count
Most-listed waterbodies in South Dakota
Waterbodies carrying the most listed impairment causes among the lake-type units reported by South Dakota.
| # | Waterbody | Listed causes |
|---|---|---|
| 1 | Freeman Lake Not Supporting | 6 |
| 2 | Lake Alvin Not Supporting | 4 |
| 2 | Lake Faulkton Not Supporting | 4 |
| 2 | Ravine Lake Not Supporting | 4 |
| 2 | Summit Lake Not Supporting | 4 |
| 6 | BearButte Lake Not Supporting | 3 |
| 6 | Beaver Lake Not Supporting | 3 |
| 6 | Burke Lake Not Supporting | 3 |
| 6 | Clear Lake Not Supporting | 3 |
| 6 | Cresbard Lake Not Supporting | 3 |
9 of the 10 rows in this table tie on the ranked value: 4 at 4 (rank 2), 5 at 3 (rank 6). 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 South Dakota
Lakes with a linked USGS gauge and a daily water-level record. Readings are daily-batch snapshots, not real-time.
States near South Dakota's heavier not-supporting load
Two EPA ATTAINS peer sets outside South Dakota. The reporting-practice chart above stays on definitive-verdict share; the neighborhoods below emphasize cross-state nearest neighbors when the not-supporting count is in the upper third.
Similar reported inventory
Nearest states by lake-type units on the register (195 here).
- Connecticut · 182 units · 13 off
- New Mexico · 176 units · 19 off
- Rhode Island · 233 units · 38 off
- Arkansas · 144 units · 51 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: 95.4% of the inventory reported from South Dakota carries a definitive verdict, 8th 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 South 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 South 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 South 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.