New York reservoir · state assessment record
Onondaga Lake, northern end
Assessment decisions reported by New York to EPA under Clean Water Act sections 303(d) and 305(b), last assessed in the 2022 reporting cycle, a cycle that carries an interim EPA action. One determination below was filed by EPA rather than by New York.
- 1,711
- Assessed acres
- Lake / Reservoir / Pond
- Water type
This waterbody in one line
Onondaga Lake, northern end, a reservoir in New York, is assessed as not supporting one or more designated uses, with 5 listed impairment causes in the state's most recent Integrated Report cycle (2022), a cycle that carries an interim EPA action. By assessed acreage it sits among the largest 5% 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
- P96
- 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.
How Onondaga Lake, northern end reads against the filed 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: in-state cause rank
Inside New York, cause-list rank is the local separator: Onondaga Lake, northern end is 3 of 428 indexed units by listed-cause count, toward the top of that state's filed lists.
Longer than most cause lists
5 listed causes puts this unit above 97% of assessed lake-type records by list length. Treat that as a coding-and-sampling signal: states that split pollutants finely mint longer lists without proving worse water.
Large assessed unit
At 1,711 acres, Onondaga Lake, northern end clears the upper tercile of assessed lake-type units with an area on file (1,534 still larger). Size comparisons use the portal's deduplicated lake ranking population, not raw ATTAINS row counts.
Every ruled-on use is not supporting
On the uses this filer ruled on, 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.
Onondaga Lake, northern end: Category 5, TMDL still owed
Category 5 is the Integrated Report band where a TMDL (or equivalent) is still expected for Onondaga Lake, northern end. Read the listed causes and any cleanup actions filed beside them before treating the overall status tile as a finished restoration story.
According to the U.S. Environmental Protection Agency's ATTAINS program, New York carries 2,231 filed lake-type waterbodies in the August 2026 extract, and this page renders the assessment record EPA assigned to Onondaga Lake, northern end 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.
| Designated use | Group | Verdict |
|---|---|---|
| Fishing | Aquatic-life or related | Not Supporting |
| Secondary Contact Recreation | Recreation | Not Supporting |
| Primary Contact Recreation | Recreation | Insufficient Information |
The record
Listed impairment causes
Causes the state and EPA listed as impairing designated uses of this reservoir, with the cycle each was first listed and the Clean Water Act action recorded against it.
| Cause | Affected uses | First listed | Cleanup standing |
|---|---|---|---|
| Dioxin | Fishing Also assessed as meeting: Primary Contact Recreation | 1998 | TMDL priority: Medium |
| Phosphorus | Secondary Contact Recreation, Fishing Also assessed as meeting: Primary Contact Recreation | 1998 | TMDL approved |
| Polychlorinated Biphenyls (PCBs) | Fishing Also assessed as meeting: Primary Contact Recreation | 1998 | TMDL priority: Medium |
| Dissolved Oxygen | Secondary Contact Recreation, Fishing | 2018 | TMDL priority: Medium |
| Mercury Filed by EPA | Fishing Also assessed as meeting: Primary Contact Recreation | 2018 | TMDL priority: Medium |
Reading the record
Where Onondaga Lake, northern end sits among peers
70% of New York's lakes assessed this deeply also had no use supported
New York ruled definitively on 2 designated uses at Onondaga Lake, northern end and found none of them supported. The dataset shows 122 New York lakes judged to that same depth.
New York's assessed lakes are most often judged on 1 use; this one was judged on 2.
Computed share from EPA ATTAINS filed records, not an official EPA rating or safety grade.
| 1 | 2 | 3 | 4 | 5+ | |
|---|---|---|---|---|---|
| All supported | 28 | 35 | 16 | 0 | 0 |
| Mixed | Not possible | 1 | 10 | 6 | 0 |
| None supported | 406 | 86 (this record) | 32 | 10 | 0 |
Ringed cell: Onondaga Lake, northern end. Source: EPA ATTAINS, Reporting cycles 1987–2026.
Scale and rank
Onondaga Lake, northern end is one of 2,231 lake-type waterbodies reported to EPA from New York, and one of 428 whose reported record carries enough populated assessment or gauge data for this site to list and index it. At 1,711 assessed acres it ranks 1,535th 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 1,534 lakes with a larger one.
Still unfiled
The state has not yet filed a definitive fish-consumption verdict for this record; that field populates when it reports it in a future Integrated Report cycle.
In context
Where Onondaga Lake, northern end 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
1,711 Top 4% larger than 96% 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 Onondaga Lake, northern end. Hover or tap any bar for its full count and share.
In context
New York context
ATTAINS carries 2,231 lake-type waterbodies in New York, 563 assessed as not supporting at least one use and 79 fully supporting. Among the 428 indexed units there, Onondaga Lake, northern end ranks 3rd by listed-cause count (5 listed causes) and 41st by assessed size among the 392 with an area filed; it sits in the not-supporting set (563 statewide) . Its listed causes include Phosphorus, Polychlorinated Biphenyls (PCBs), Dissolved Oxygen, and Mercury, which also appear among New York's most-filed impairment causes (led by pH). It also lists Dioxin, outside that top-five list.
| Other large assessed lakes in New York | Assessed acres |
|---|---|
| Lake Champlain, Main Lake, Middle Not Supporting | 54,972 |
| Oneida Lake Not Supporting | 51,269 |
| Seneca Lake, Main Lake, Middle Fully Supporting | 40,290 |
| Cayuga Lake, Main Lake, Mid-South Fully Supporting | 33,083 |
| Lake George Not Supporting | 28,523 |
| Great Sacandaga Lake Not Supporting | 24,722 |
Peers near Onondaga Lake, northern end's size or cause load
Similar assessed acres
Nearest filed extents (1,711 acres here).
- Manistique Lake, North · 1,712 acres · MI
- Twistal Swamp · 1,713 acres · MN
- Fall Creek Lake · 1,716 acres · OR
- Eagle Mountain Reservoir · 1,705 acres · TX
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 NY0702-0003. 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.