Massachusetts lake · state assessment record
Onota Lake
Assessment decisions reported by Massachusetts to EPA under Clean Water Act sections 303(d) and 305(b), last assessed in the 2026 reporting cycle, a cycle that is open for public comment.
- 664
- Assessed acres
- Lake, Freshwater
- Water type
This waterbody in one line
Onota Lake, a lake in Massachusetts, is assessed as not supporting one or more designated uses, with 5 listed impairment causes in the state's most recent Integrated Report cycle (2026), a cycle that is open for public comment. By assessed acreage it sits among the largest 10% by assessed acreage nationally (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.
- Not Supporting
- overall status
- P92
- 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.
Onota Lake against the ATTAINS register
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, aquatic life, every determination is Not Supporting. That is a use-by-use reading of the filed record, not a single overall lake grade.
Large assessed unit
At 664 acres, Onota Lake clears the upper tercile of assessed lake-type units with an area on file (3,048 still larger). Size comparisons use the portal's deduplicated lake ranking population, not raw ATTAINS row counts.
Onota Lake: Category 5, TMDL still owed
Category 5 is the Integrated Report band where a TMDL (or equivalent) is still expected for Onota Lake. Read the listed causes and any cleanup actions filed beside them before treating the overall status tile as a finished restoration story.
Large within Massachusetts
Among Massachusetts's 678 indexed units with an area, Onota Lake ranks 11 by assessed size, toward the large end of that state file.
According to the U.S. Environmental Protection Agency's ATTAINS program, Massachusetts carries 1,191 filed lake-type waterbodies in the August 2026 extract, and this page renders the assessment record EPA assigned to Onota Lake 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. For the one definitive verdict on this record, Massachusetts filed the assessment basis as Monitored Data. Those are EPA's own words, not PlainLakes' summary of them.
| Designated use | Group | Verdict |
|---|---|---|
| Fish, Other Aquatic Life and Wildlife | Aquatic-life or related | Not Supporting |
| Aesthetic | Other | Not Assessed |
| Fish Consumption | Fish-consumption or fishery | Insufficient Information |
| Primary Contact Recreation | Recreation | Not Assessed |
| Secondary Contact Recreation | Recreation | Not Assessed |
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 |
|---|---|---|---|
| Eurasian Water Milfoil, Myriophyllum Spicatum | Fish, Other Aquatic Life and Wildlife | 1992 | None reported |
| Brittle Naiad, Najas Minor | Fish, Other Aquatic Life and Wildlife | 2020 | None reported |
| Curly-Leaf Pondweed | Fish, Other Aquatic Life and Wildlife | 2020 | None reported |
| Dissolved Oxygen | Fish, Other Aquatic Life and Wildlife | 2020 | TMDL priority: Low |
| Water Chestnut | Fish, Other Aquatic Life and Wildlife | 2020 | 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.
- Eurasian Water Milfoil, Myriophyllum Spicatum
- Introduction of Non-Native Organisms (Accidental or Intentional) (confirmed)
- Brittle Naiad, Najas Minor
- Introduction of Non-Native Organisms (Accidental or Intentional) (confirmed)
- Curly-Leaf Pondweed
- Introduction of Non-Native Organisms (Accidental or Intentional) (confirmed)
- Water Chestnut
- Introduction of Non-Native Organisms (Accidental or Intentional) (confirmed)
Massachusetts also recorded the source of at least one listing here as unknown, including for Dissolved Oxygen.
Reading the record
Where Onota Lake sits among peers
95% of Massachusetts's lakes assessed this deeply also had no use supported (the standard result at this depth, not a distinction)
Massachusetts ruled definitively on a single designated use at Onota Lake and found it not supported. The dataset shows 298 Massachusetts lakes judged to that same depth.
Massachusetts's assessed lakes are most often judged on 1 use, as this one was.
Computed share from EPA ATTAINS filed records, not an official EPA rating or safety grade.
| 1 | 2 | 3 | 4 | 5+ | |
|---|---|---|---|---|---|
| All supported | 15 | 14 | 11 | 0 | 0 |
| Mixed | Not possible | 5 | 19 | 31 | 12 |
| None supported | 283 (this record) | 60 | 91 | 128 | 49 |
Ringed cell: Onota Lake. Source: EPA ATTAINS, Reporting cycles 1987–2026.
Scale and rank
Onota Lake is one of 1,191 lake-type waterbodies reported to EPA from Massachusetts, and one of 678 whose reported record carries enough populated assessment or gauge data for this site to list and index it. At 664 assessed acres it ranks 3,049th 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 3,048 lakes with a larger one.
Not yet on record
The state has not yet filed a definitive fish-consumption verdict and a definitive recreation verdict for this record; those fields populate when it reports them in a future Integrated Report cycle.
In context
Where Onota Lake 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
664 Top 8% larger than 92% 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 Onota Lake. Hover or tap any bar for its full count and share.
In context
Massachusetts context
ATTAINS carries 1,191 lake-type waterbodies in Massachusetts, 678 assessed as not supporting at least one use and 40 fully supporting. Among the 678 indexed units there, Onota Lake ranks 53rd by listed-cause count (5 listed causes) and 11th by assessed size among the 678 with an area filed; it sits in the not-supporting set (678 statewide) . Its listed causes include Dissolved Oxygen, which also appears among Massachusetts's most-filed impairment causes (led by Mercury in Fish Tissue). It also lists Eurasian Water Milfoil, Myriophyllum Spicatum; Brittle Naiad, Najas Minor; Curly-Leaf Pondweed; and Water Chestnut, outside that top-five list.
| Other large assessed lakes in Massachusetts | Assessed acres |
|---|---|
| Quabbin Reservoir Not Supporting | 24,010 |
| Wachusett Reservoir Not Supporting | 3,962 |
| Assawompset Pond Not Assessed | 2,034 |
| North Watuppa Pond Not Supporting | 1,728 |
| Long Pond Not Supporting | 1,728 |
| South Watuppa Pond Not Supporting | 1,473 |
Peers near Onota Lake's size or cause load
Similar assessed acres
Nearest filed extents (664 acres here).
- Silver Lake · 664 acres · IA
- Lake Austin · 664 acres · TX
- Fossil Creek Reservoir. · 664 acres · CO
- Trenton Lake · 664 acres · ND
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
- Assessment verdicts are cycle-based, not real-time. For fish-consumption decisions, your state advisory program is the binding source. 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 MA21078. 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.