Rhode Island lake · state assessment record
Mashapaug Pond
Assessment decisions reported by Rhode Island to EPA under Clean Water Act sections 303(d) and 305(b), last assessed in the 2024 reporting cycle.
- 77
- Assessed acres
- Lake, Freshwater
- Water type
This waterbody in one line
Mashapaug Pond, a lake in Rhode Island, is assessed as not supporting one or more designated uses, with 5 listed impairment causes in the state's most recent Integrated Report cycle (2024). By assessed acreage it sits above the national median by assessed acreage (38,628 lakes); its impairment list is among the longest nationally (5 listed causes vs 23,610 assessed lakes). Aquatic life is assessed as not supporting. Fish consumption is assessed as not supporting.
- Not Supporting
- overall status
- P64
- Assessed size nationally
- P1
- Shorter cause list
- Not Supporting
- aquatic life
Assessment verdicts are the state agency's decisions as reported to EPA ATTAINS; PlainLakes renders them without modification.
A composite of this record's EPA ATTAINS designated-use verdicts, filed impairment count, and assessment currency, weighted and benchmarked against the national corpus of assessed active waterbodies. This is a water-quality standing, not a human-recreation or property-value judgment, and dimensions with no filed verdict drop out rather than count against the score.
Reading Mashapaug Pond's filed record
Paragraphs are selected by this unit's percentiles and use matrix: different lakes lead with different dimensions. Figures are ATTAINS / portal register arithmetic, not advice.
The signature stat: cause-list length
The standout filed fact is cause-list length: 5 listed impairment causes, a longer list than 97% of assessed lake-type units (n=23,610). List length tracks how states sample and code, not a severity score.
Every filed use falls short
On the uses this filer ruled on, fish consumption, recreation, aquatic life, every determination is Not Supporting. That is a use-by-use reading of the filed record, not a single overall lake grade.
Mashapaug Pond: Category 5, TMDL still owed
Category 5 is the Integrated Report band where a TMDL (or equivalent) is still expected for Mashapaug Pond. Read the listed causes and any cleanup actions filed beside them before treating the overall status tile as a finished restoration story.
Overall status: not supporting
The filer's overall status for Mashapaug Pond is Not Supporting. That tile summarizes the assessment unit; the designated-use rows and cause list are the evidence behind it.
Mid-pack assessed size
76.7 acres lands in the middle tercile of units with an area filed. Acreage is not what distinguishes this record from its peers.
According to the U.S. Environmental Protection Agency's ATTAINS program, Rhode Island carries 233 filed lake-type waterbodies in the August 2026 extract, and this page renders the assessment record EPA assigned to Mashapaug Pond without modification. See our methodology for reporting-unit limits and gauge linking rules.
The record
Designated-use assessments
Fully Supporting and Not Supporting are the state's definitive verdicts; other entries mean the use was not conclusively assessed in this cycle. Rhode Island filed its own confidence on the 4 definitive verdicts it rated: Excellent. That rating is the filer's, in EPA's own field, and EPA publishes no definition of the four words it offers.
| Designated use | Group | Verdict |
|---|---|---|
| Fish Consumption | Fish-consumption or fishery | Not Supporting Filer confidence: Excellent |
| Fish and Wildlife Habitat | Aquatic-life or related | Not Supporting Filer confidence: Excellent |
| Primary Contact Recreation | Recreation | Not Supporting Filer confidence: Excellent |
| Secondary Contact Recreation | Recreation | Not Supporting Filer confidence: Excellent |
The record
Listed impairment causes
Causes the state listed as impairing designated uses of this lake, with the cycle each was first listed and the Clean Water Act action recorded against it.
| Cause | Affected uses | First listed | Cleanup standing |
|---|---|---|---|
| Dissolved Oxygen | Fish and Wildlife Habitat | 1992 | TMDL approved |
| Phosphorus, Total | Fish and Wildlife Habitat | 1998 | TMDL approved |
| Chlorophyll-a | Fish and Wildlife Habitat | 2002 | TMDL approved |
| Fecal Coliform | Secondary Contact Recreation, Primary Contact Recreation | 2002 | TMDL approved |
| PCBs in Fish Tissue | Fish Consumption | 2004 | None reported |
Probable sources named by the state
Each source below is listed under the cause the state filed it against, and carries the word the state filed with it — confirmed, or suspected.
- Dissolved Oxygen
- Wildlife Other Than Waterfowl (confirmed) Upstream/Downstream Source (confirmed) Wastes From Pets (confirmed) Waterfowl (confirmed) Urban Runoff/Storm Sewers (confirmed)
- Phosphorus, Total
- Wildlife Other Than Waterfowl (confirmed) Upstream/Downstream Source (confirmed) Wastes From Pets (confirmed) Waterfowl (confirmed) Urban Runoff/Storm Sewers (confirmed)
- Chlorophyll-a
- Wildlife Other Than Waterfowl (confirmed) Upstream/Downstream Source (confirmed) Wastes From Pets (confirmed) Waterfowl (confirmed) Urban Runoff/Storm Sewers (confirmed)
- Fecal Coliform
- Wildlife Other Than Waterfowl (confirmed) Wastes From Pets (confirmed) Urban Runoff/Storm Sewers (confirmed)
Rhode Island also recorded the source of at least one listing here as unknown, including for PCBs in Fish Tissue.
Reading the record
Where Mashapaug Pond sits among peers
5% of Rhode Island's lakes assessed this deeply also had no use supported
Rhode Island ruled definitively on 4 designated uses at Mashapaug Pond and found none of them supported. The dataset shows 37 Rhode Island lakes judged to that same depth.
Rhode Island's assessed lakes are most often judged on 1 use; this one was judged on 4.
Computed share from EPA ATTAINS filed records, not an official EPA rating or safety grade.
| 1 | 2 | 3 | 4 | 5+ | |
|---|---|---|---|---|---|
| All supported | 7 | 7 | 6 | 1 | 0 |
| Mixed | Not possible | 3 | 16 | 34 | 1 |
| None supported | 36 | 23 | 4 | 2 (this record) | 0 |
Ringed cell: Mashapaug Pond. Source: EPA ATTAINS, Reporting cycles 1987–2026.
Scale and rank
Mashapaug Pond is one of 233 lake-type waterbodies reported to EPA from Rhode Island, and one of 126 whose reported record carries enough populated assessment or gauge data for this site to list and index it. At 77 assessed acres it ranks 13,845th by assessed size among the 38,628 lakes the dataset carries an area for, counting a state’s repeated filings of one water once, behind 13,844 lakes with a larger one.
Reported trophic class
Rhode Island carried the trophic field for this assessment unit and filed it as unclassified, which records that no class was determined rather than that the water is unenriched. What the trophic scale measures.
Why no water-level record
Mashapaug Pond has no daily USGS water-level or reservoir-storage series on this page because NWIS lists a lake monitoring site named for the waterbody, but the site is not active, and PlainLakes ingests only the active inventory, so there is no series to attach. How PlainLakes links gauges.
In context
Where Mashapaug Pond sits nationally
Assessed size among U.S. lakes
Distribution of assessed acreage across ATTAINS lakes filed with an area, counting a state’s repeated filings of one water once
77 Top 36% larger than 64% of 38,628 lakes
lakes the dataset carries an area for, counting a state’s repeated filings of one water once, bucketed by value
Source EPA ATTAINS · Reporting cycles 1987–2026
Listed causes vs waterbodies carrying a verdict
How many impairment causes U.S. waterbodies with a reported verdict carry
5 Longer than most more listed causes than 97% of 23,610 waterbodies carrying a verdict
named waterbodies carrying a verdict, bucketed by value
Source EPA ATTAINS · Reporting cycles 1987–2026
In both charts each bar is a band and taller bars hold more waterbodies; the dashed line and filled bar mark Mashapaug Pond. Hover or tap any bar for its full count and share.
In context
Rhode Island context
ATTAINS carries 233 lake-type waterbodies in Rhode Island, 119 assessed as not supporting at least one use and 21 fully supporting. Among the 126 indexed units there, Mashapaug Pond ranks 5th by listed-cause count (5 listed causes) and 49th by assessed size among the 126 with an area filed; it sits in the not-supporting set (119 statewide) . Its listed causes include Dissolved Oxygen; Phosphorus, Total; and Chlorophyll-a, which also appear among Rhode Island's most-filed impairment causes (led by Non-Native Aquatic Plants). It also lists Fecal Coliform and PCBs in Fish Tissue, outside that top-five list.
| Other large assessed lakes in Rhode Island | Assessed acres |
|---|---|
| Scituate Reservoir Fully Supporting | 3,277 |
| Worden Pond Not Supporting | 1,051 |
| Flat River Reservoir (Johnson Pond) Not Supporting | 647 |
| Watchaug Pond Not Supporting | 568 |
| Stafford Pond Not Supporting | 480 |
| Watson Reservoir Not Supporting | 371 |
Peers near Mashapaug Pond's size or cause load
Similar assessed acres
Nearest filed extents (77 acres here).
- Dunn Lake · 77 acres · WI
- Smith Mtn. Lake (Lynville Creek) · 77 acres · VA
- Rustad-Melby · 77 acres · MN
- Pelt · 77 acres · MN
Similar cause load
Nearest listed-cause counts (5 here). Peers already in the acreage column are omitted.
- Alexandria Lake No. 3 · 5 causes · NE
- Alexauken Ck (above 74d 55m) · 5 causes · NJ
- Alexauken Ck (below 74d 55m to 11BA06) · 5 causes · NJ
- Alloway Ck (Quinton to Alloway-WdstwnRd) · 5 causes · NJ
What to do with this record
- The fish-consumption use is assessed as not supporting. Before eating fish from this lake, check your state fish-advisory program for species-specific meal limits. Consumption status guide
- Impairment listings follow the Clean Water Act 303(d) process; a listing is a regulatory finding, not a closure notice. 303(d) explained
PlainLakes renders state assessment decisions and federal gauge observations without modification. It does not issue advisories.
Assessment decisions on this page are rendered directly from state Integrated Report records in EPA's ATTAINS system; gauge figures are daily-value observations from the USGS National Water Information System, no number is typed in by an editor. Overall status, use verdicts, and causes are the state's reported decisions for assessment unit RI0006017L-06. Counts and percentiles are computed across all lake-type records PlainLakes ingests from ATTAINS. 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.