New York reservoir · state assessment record
Cayuga Lake, Main Lake, Mid-South
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.
- 33,083
- Assessed acres
- Lake / Reservoir / Pond
- Water type
This waterbody in one line
Cayuga Lake, Main Lake, Mid-South, a reservoir in New York, is assessed as fully supporting its designated uses, with no impairment causes listed 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 1% of assessed lakes nationally (38,628 lakes with a filed area); its impairment list is shorter than on half of assessed lakes (0 listed causes).
- Fully Supporting
- overall status
- P100
- Assessed size nationally
- P51
- Shorter cause list
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.
Where Cayuga Lake, Main Lake, Mid-South stands in 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: assessed size
The number that most separates Cayuga Lake, Main Lake, Mid-South nationally is assessed size: 33,083 acres, larger than 100% of the 38,628 lake-type units with an area on file.
Shorter than most cause lists
Only 0 causes on file, shorter than 51% of assessed lake-type units. Pair the short list with the use matrix: a single Not Supporting use can still be the whole story.
Every filed use clears the bar
The filed use determinations for recreation are all Fully Supporting. Where an overall IR category still flags the unit, look at the cause list and report standing rather than treating the use row as empty.
IR category in the supporting band
EPA's Integrated Report category for Cayuga Lake, Main Lake, Mid-South is 2. In ATTAINS that band means the assessed uses are supporting (or supporting with other waters in the unit), so the narrative weight shifts to how deep the assessment went and whether monitoring is current, not to a restoration plan.
Overall status: fully supporting
Overall status is Fully Supporting. If an IR category or cause row still appears, it usually reflects a prior listing path or a use the overall rollup does not collapse, read those sections rather than stopping at the tile.
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 Cayuga Lake, Main Lake, Mid-South 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 |
|---|---|---|
| Primary Contact Recreation | Recreation | Fully Supporting |
| Secondary Contact Recreation | Recreation | Fully Supporting |
| Water Supply | Drinking-water supply designation | Fully Supporting |
| Fishing | Aquatic-life or related | Insufficient Information |
The record
Listed impairment causes
The state's reported assessment lists no impairment causes for this reservoir.
Reading the record
Cayuga Lake, Main Lake, Mid-South: Category 2 reading
2 Category 2: some uses supported, others not assessed
New York filed this assessment unit as Category 2: some designated uses are supported and others were not assessed in this cycle. Absence of a failing verdict is not the same as a full Category 1 finding.
Scale and rank
Cayuga Lake, Main Lake, Mid-South is one of 2,231 lake-type waterbodies reported to EPA from New York. It is not among the 428 whose reported record carries enough populated assessment or gauge data for this site to list and index it. At 33,083 assessed acres it ranks 90th 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 89 lakes with a larger one.
What this record holds
New York completed an assessment here and listed no impairment cause, so the record holds a verdict and its supporting use rows but no pollutant to track over time. The state has not yet filed a definitive fish-consumption verdict and a definitive aquatic-life verdict for this record; those fields populate when it reports them in a future Integrated Report cycle.
In context
Where Cayuga Lake, Main Lake, Mid-South 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
33,083 Top 1% larger than 99%+ 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
0 Among the shortest cause lists fewer listed causes than 51% 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 Cayuga Lake, Main Lake, Mid-South. 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.
| 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 |
| Lake George Not Supporting | 28,523 |
| Great Sacandaga Lake Not Supporting | 24,722 |
| Lake Champlain, Main Lake, North Not Supporting | 18,335 |
Peers near Cayuga Lake, Main Lake, Mid-South's size or cause load
Similar assessed acres
Nearest filed extents (33,083 acres here).
- Canyon Ferry Reservoir · 32,810 acres · MT
- Lake Okeechobee · 32,687 acres · FL
- Toledo Bend Reservoir · 33,555 acres · TX
- Mooselookmeguntic Lake · 32,243 acres · ME
Similar cause load
Nearest listed-cause counts (0 here). Peers already in the acreage column are omitted.
- 31st Street Harbor · 0 causes · IL
- 42nd Avenue East Beach · 0 causes · MN
- 59th Street Harbor · 0 causes · IL
- 657 Dunleavy (Beach) · 0 causes · MI
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 NY0705-0050. 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.