State water-quality picture · #31 by reported lake-type waterbodies
Rhode Island lakes and reservoirs
Every figure on this page is computed from the assessment decisions Rhode Island reported to the U.S. Environmental Protection Agency under Clean Water Act sections 303(d) and 305(b) (reporting cycles 2009–2024), plus daily water-level observations from the U.S. Geological Survey.
- 233
- Reported waterbodies
- 119
- Not supporting a use
- 48
- Fish use not supporting
- 0
- Gauged lakes
Rhode Island in one line
233 lake-type waterbodies in Rhode Island are reported to EPA ATTAINS across reporting cycles 2009–2024: 119 assessed as not supporting at least one designated use, 21 fully supporting, and 93 without a definitive overall verdict. The most-listed impairment cause is Non-Native Aquatic Plants, on 74 waterbodies.
- 233
- reported waterbodies
- 119
- not supporting a use
- 21
- fully supporting
- 85%
- of definitive verdicts impaired
An unassessed waterbody is neither confirmed clean nor confirmed impaired; states assess on multi-year cycles.
Rhode Island's mid-size register with a heavier not-supporting share
Rhode Island sits in the middle third by inventory size (233 units) and in the upper third for ruled not-supporting share (85%).
Data updated 2026-08-17
According to the U.S. Environmental Protection Agency's ATTAINS program, Rhode Island reported 233 lake-type waterbodies in Rhode Island in the August 2026 extract. See our methodology for filer attribution and multi-year reporting cycles.
Overall-status mix on Rhode Island's mid-size inventory
Every reported lake-type unit in Rhode Island 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 Rhode Island
Waterbodies carrying each listed cause, most first
- Non-Native Aquatic Plants
Non-Native Aquatic Plants
74 waterbodies
- Mercury in Fish Tissue
Mercury in Fish Tissue
47 waterbodies
- Phosphorus, Total
Phosphorus, Total
46 waterbodies
- Dissolved Oxygen 20
Dissolved Oxygen
20 waterbodies
- Chlorophyll-a 9
Chlorophyll-a
9 waterbodies
What this shows Non-Native Aquatic Plants is the most-listed impairment cause in Rhode Island, on 74 of the lake-type waterbodies reported there.
Computed share from EPA ATTAINS filed records, not an official EPA rating or safety grade.
Rhode Island: 85% of ruled verdicts are not-supporting, against a national share of 53%, 1.6× the national rate.
Reporting practice
Rhode Island's definitive-verdict share, by the numbers
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.
Rhode Island holds the 31st-largest reported lake-type inventory in the country, 233 assessment units, carrying a definitive verdict on 60.1% of it. The counts above describe the 140 units carrying a verdict, not all 233 reported. Rhode Island 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 Massachusetts (60.3%) and Iowa (54.7%).
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.
Rhode Island against every comparable state
Share of reported lake-type waterbodies carrying a definitive verdict
60.1% 29th of 47 higher than 18 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 Rhode Island
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 | Scituate Reservoir Fully Supporting | 3,277 |
| 2 | Worden Pond Not Supporting | 1,051 |
| 3 | Flat River Reservoir (Johnson Pond) Not Supporting | 647 |
| 4 | Watchaug Pond Not Supporting | 568 |
| 5 | Stafford Pond Not Supporting | 480 |
| 6 | Watson Reservoir Not Supporting | 371 |
| 7 | Diamond Hill Reservoir Not Assessed | 358 |
| 8 | Echo Lake (Pascoag Reservoir) Not Supporting | 349 |
| 9 | Woonasquatucket Reservoir (Stump Pond) Not Supporting | 303 |
| 10 | Moswansicut Pond Not Assessed | 281 |
| 11 | Indian Lake Not Supporting | 265 |
| 12 | Waterman Reservoir Not Supporting | 252 |
By cause count
Most-listed waterbodies in Rhode Island
Waterbodies carrying the most listed impairment causes among the lake-type units reported by Rhode Island.
| # | Waterbody | Listed causes |
|---|---|---|
| 1 | Omega Pond Not Supporting | 6 |
| 2 | Kickemuit Reservoir (Warren Reservoir) Not Supporting | 5 |
| 2 | Mashapaug Pond Not Supporting | 5 |
| 2 | Print Works Pond Not Supporting | 5 |
| 2 | Roger Williams Park Ponds Not Supporting | 5 |
| 2 | Three Ponds Not Supporting | 5 |
| 2 | Turner Reservoir North (Central Pond) Not Supporting | 5 |
| 2 | Turner Reservoir South Not Supporting | 5 |
| 2 | Valley Falls Pond Not Supporting | 5 |
| 10 | Chapman Pond Not Supporting | 4 |
8 of the 10 rows in this table tie on the ranked value: 8 at 5 (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 Rhode Island's heavier not-supporting load
Two EPA ATTAINS peer sets outside Rhode Island. 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.
Comparable register size
Nearest states by lake-type units on the register (233 here).
- South Dakota · 195 units · 38 off
- Virginia · 275 units · 42 off
- Connecticut · 182 units · 51 off
- New Mexico · 176 units · 57 off
Comparable not-supporting counts
Nearest states by units assessed not supporting a use (119 here). Inventory peers above are omitted.
- Texas · 125 not supporting · 6 off
- Pennsylvania · 135 not supporting · 16 off
- Iowa · 137 not supporting · 18 off
- Alabama · 143 not supporting · 24 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: 60.1% of the inventory reported from Rhode Island carries a definitive verdict, 29th 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 Rhode Island 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 Rhode Island 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 Rhode Island, 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.