Updated Aug 2026
South Carolina Lake Water Quality
Water quality grades for 6 monitored lakes across 5 counties.
Across South Carolina, 6 lakes carry an active water-quality grade spread over 5 counties. The underlying measurements come from the South Carolina Department of Health and Environmental Control, alongside federal programs and volunteer monitoring networks. Only about 0% of South Carolina's lakes pull an A grade — the smaller, agricultural-watershed lakes that dominate the dataset tend to carry persistent nutrient loads. 17% of lakes fall in the D or F brackets.
Eutrophic conditions dominate — nutrient-loaded, productive, with algal pressure that shows up most years in late summer. These lakes tend to be shallow, agricultural-watershed, and over-warmed by the time July ends. Clarendon ranks highest on average county grade (B). York sits lowest. With only 5 counties in the state, the cross-county spread is narrower than the within-county spread for most lakes.
Grade Distribution
All 6 South Carolina lakes in the index: 5 (83.3%) carry an A–F grade and 1 (16.7%) are not rated, because they lack enough recent nutrient or algae sampling to support a letter.
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Top-Graded South Carolina Lakes
The highest water-quality grades in South Carolina — clarity, depth, and A-F grade at a glance.
Lake Map
South Carolina reports, fishing & travel
South Carolina Fishing & Recreation
Licenses, regulations, records, and where to fish across South Carolina.
Counties
All 5 South Carolina counties, ranked by average lake water quality. Compare them against every county nationwide in the county rankings, browse the full directory of graded lakes, or pick a different state.
Cleanest South Carolina Lakes
5 lakes5 graded lakes
| # | Lake | County | Grade | Clarity | Trophic | Access |
|---|---|---|---|---|---|---|
| 1 | BLake Marion | Clarendon | B | 4.3 ft | Eutrophic | Not recorded |
| 2 | BLake Moultrie | Berkeley | B | 4.9 ft | Eutrophic | Not recorded |
| 3 | CClarks Hill Lake | McCormick | C | 9.2 ft | Mesotrophic | Not recorded |
| 4 | CLake Tugalo | Oconee | C | 7.9 ft | Mesotrophic | Not recorded |
| 5 | DLake Wylie | York | D | No recent samples | Eutrophic | Not recorded |
South Carolina Lakes Needing Attention
5 lakes5 graded lakes
| # | Lake | County | Grade | Clarity |
|---|---|---|---|---|
| 1 | DLake Wylie | York | D | No recent samples |
| 2 | CLake Tugalo | Oconee | C | 7.9 ft |
| 3 | CClarks Hill Lake | McCormick | C | 9.2 ft |
| 4 | BLake Moultrie | Berkeley | B | 4.9 ft |
| 5 | BLake Marion | Clarendon | B | 4.3 ft |
Lake Match
Which lake suits how you actually use one?
Six questions — swimming, fishing, quiet, cabins, drive time — and a shortlist of graded lakes that fit, with the water quality behind each one.
Source: EPA National Aquatic Resource Surveys and the EPA Water Quality Portal.
More on lake water quality
The top-graded lake in every state we cover, picked grade-first with water clarity as the tie-breaker — plus the states whose winner is still not clean.
State-by-state Secchi champions: the clearest measured lake in each U.S. state we grade, which is not the same as the cleanest nutrient grade.
A data snapshot of the lakes we grade: how the A–F distribution breaks down, the clearest and the greenest states, and where the water is improving.
How lakes are graded A–F on nutrients and algae using EPA ecoregion condition classes, what each letter means in the water, and why an A is not a clearance.