Some of these decisions are EPA's. 4 of these 611 records carry a Clean Water Act cleanup plan EPA established rather than South Carolina. They are counted in every figure on this page, and each record page names which.
State water-quality picture · #16 by reported lake-type waterbodies
South Carolina lakes and reservoirs
Every figure on this page is computed from the assessment decisions South Carolina reported to the U.S. Environmental Protection Agency under Clean Water Act sections 303(d) and 305(b) (reporting cycles 2014–2024), plus daily water-level observations from the U.S. Geological Survey.
- 611
- Reported waterbodies
- 212
- Not supporting a use
- 22
- Fish use not supporting
- 0
- Gauged lakes
South Carolina in one line
611 lake-type waterbodies in South Carolina are reported to EPA ATTAINS across reporting cycles 2014–2024: 212 assessed as not supporting at least one designated use, 328 fully supporting, and 71 without a definitive overall verdict. The most-listed impairment cause is Phosphorus, Total, on 94 waterbodies.
- 611
- reported waterbodies
- 212
- not supporting a use
- 328
- fully supporting
- 39%
- of definitive verdicts impaired
An unassessed waterbody is neither confirmed clean nor confirmed impaired; states assess on multi-year cycles.
A large South Carolina inventory with a lighter ruled-impairment share
611 reported lake-type units put South Carolina in the largest third of state registers, while its ruled not-supporting share (39%) sits in the lowest third. Scale and load pull apart on this page.
Data updated 2026-08-17
According to the U.S. Environmental Protection Agency's ATTAINS program, South Carolina reported 611 lake-type waterbodies in South Carolina in the August 2026 extract. See our methodology for filer attribution and multi-year reporting cycles.
How South Carolina's large inventory splits across overall status
Each of the 611 lake-type units reported by South Carolina lands in exactly one overall-status bucket. On a register this large, the bar is an inventory partition, the cause chart and national gauge below answer different questions.
Most-listed impairment causes in South Carolina
Waterbodies carrying each listed cause, most first
- Phosphorus, Total
Phosphorus, Total
94 waterbodies
- pH
pH
88 waterbodies
- Chlorophyll-a 30
Chlorophyll-a
30 waterbodies
- Escherichia coli (E. coli) 28
Escherichia coli (E. coli)
28 waterbodies
- Nitrogen, Total 22
Nitrogen, Total
22 waterbodies
What this shows Phosphorus, Total is the most-listed impairment cause in South Carolina, on 94 of the lake-type waterbodies reported there.
Computed share from EPA ATTAINS filed records, not an official EPA rating or safety grade.
South Carolina: 39% of ruled verdicts are not-supporting, against a national share of 53%, 1.4× below the national rate.
Reporting practice
Nearly all of South Carolina's inventory carries a definitive verdict
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 Carolina holds the 16th-largest reported lake-type inventory in the country, 611 assessment units, carrying a definitive verdict on 88.4% of it. The counts above describe the 540 units carrying a verdict, not all 611 reported.
The states reporting at the nearest rates are Texas (88.5%) and Mississippi (86%).
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 Carolina against every comparable state
Share of reported lake-type waterbodies carrying a definitive verdict
88.4% 15th of 47 higher than 32 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 cause count
Most-listed waterbodies in South Carolina
Waterbodies carrying the most listed impairment causes among the lake-type units reported by South Carolina.
| # | Waterbody | Listed causes |
|---|---|---|
| 1 | S-309 Not Supporting | 5 |
| 2 | C-058 Not Supporting | 4 |
| 2 | Cl-035 Not Supporting | 4 |
| 2 | Cw-057 Not Supporting | 4 |
| 2 | Rl-03331 Not Supporting | 4 |
| 2 | Rl-09100 Not Supporting | 4 |
| 2 | Rl-10104 Not Supporting | 4 |
| 2 | Rl-19154 Not Supporting | 4 |
| 2 | Sv-268 Not Supporting | 4 |
| 10 | Cl-064 Not Supporting | 3 |
8 of the 10 rows in this table tie on the ranked value: 8 at 4 (rank 2). 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.
States near South Carolina's lighter not-supporting load
Two EPA ATTAINS peer sets outside South Carolina. The reporting-practice chart above stays on definitive-verdict share; these neighborhoods highlight register-size and not-supporting peers while South Carolina's ruled impairment share sits in the lowest third.
States with a similar reported inventory
Nearest states by lake-type units on the register (611 here).
- New Jersey · 611 units · 0 off
- California · 607 units · 4 off
- Missouri · 623 units · 12 off
- Idaho · 630 units · 19 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: 88.4% of the inventory reported from South Carolina carries a definitive verdict, 15th 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 Carolina 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 Carolina 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 Carolina, 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.