Updated Aug 2026
Rhode Island Lake Water Quality
Water quality grades for 5 monitored lakes across 2 counties.
Rhode Island has 5 graded lakes in our dataset, sampled across 2 counties, drawing on monitoring by the Rhode Island Department of Environmental Management plus federal and volunteer measurements. Only about 0% of Rhode Island's lakes pull an A grade — the smaller, agricultural-watershed lakes that dominate the dataset tend to carry persistent nutrient loads. 0% of lakes fall in the D or F brackets.
The state's dominant trophic class is oligotrophic: clear, nutrient-poor, slow-growing. These lakes are also the most sensitive to disturbance — the same volume that buffers them against nutrients also slows recovery if those nutrients arrive in quantity. a leading county ranks highest on average county grade (—). a struggling county sits lowest. With only 2 counties in the state, the cross-county spread is narrower than the within-county spread for most lakes.
Grade Distribution
All 5 Rhode Island lakes in the index: 0 (0.0%) carry an A–F grade and 5 (100.0%) are not rated, because they lack enough recent nutrient or algae sampling to support a letter.
Where to stay near Rhode Island
Top-rated places to stay near Rhode Island
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Lake Map
Rhode Island reports, fishing & travel
Rhode Island Fishing & Recreation
Licenses, regulations, records, and where to fish across Rhode Island.
Counties
All 2 Rhode Island 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.
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.