New York reservoir · state assessment record
Great Sacandaga Lake
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.
- 24,722
- Assessed acres
- Lake / Reservoir / Pond
- Water type
- 762.1 ft
- Water Surface Elevation (provisional)
This waterbody in one line
Great Sacandaga Lake, a reservoir in New York, is assessed as not supporting one or more designated uses, with 2 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 1% of assessed lakes nationally (38,628 lakes with a filed area); its impairment list is among the longest nationally (2 listed causes vs 23,610 assessed lakes). A USGS gauge tracks its water surface elevation daily.
- Not Supporting
- overall status
- P100
- Assessed size nationally
- P10
- Shorter cause list
Assessment verdicts are the state agency's decisions as reported to EPA ATTAINS; PlainLakes renders them without modification.
How Great Sacandaga Lake 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: assessed size
The number that most separates Great Sacandaga Lake nationally is assessed size: 24,722 acres, larger than 100% of the 38,628 lake-type units with an area on file.
Great Sacandaga Lake: Category 4A reading
Category 4A means a TMDL (or equivalent) is already approved for the impairment on Great Sacandaga Lake. The remaining work is implementation and tracking, read the cleanup-standing and cause rows for what the state already committed to address.
Longer than most cause lists
2 listed causes puts this unit above 80% 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.
Overall status: not supporting
The filer's overall status for Great Sacandaga Lake is Not Supporting. That tile summarizes the assessment unit; the designated-use rows and cause list are the evidence behind it.
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 Great Sacandaga 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.
| Designated use | Group | Verdict |
|---|---|---|
| Fishing | Aquatic-life or related | Insufficient Information |
| Primary Contact Recreation | Recreation | Insufficient Information |
| Secondary Contact Recreation | Recreation | Insufficient Information |
The record
Listed impairment causes
Causes the state 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 |
|---|---|---|---|
| Mercury | Fishing Also assessed as meeting: Secondary Contact Recreation, Primary Contact Recreation | 2010 | TMDL approved |
| Flow Alteration-Changes in Depth and Flow Velocity | None; the 3 uses assessed against it were met | Not reported | TMDL priority: Medium |
Reading the record
Great Sacandaga Lake: Category 4A reading
4A Category 4A: impaired, TMDL completed
New York filed this assessment unit as Category 4A: impaired, with a pollutant-budget TMDL already completed under 303(d). The listing remains an impairment finding; the plan is on file rather than still awaiting write-up.
Scale and rank
Great Sacandaga Lake 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 24,722 assessed acres it ranks 126th 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 125 lakes with a larger one.
Water level
A USGS gauge tracks this reservoir's water surface elevation daily, and the latest reading is 1.85 ft below the reading 32 days earlier, against a 365-day observed range of 19.6 ft. The state has not yet filed a definitive fish-consumption verdict, a definitive recreation verdict, and a definitive aquatic-life verdict for this record; those fields populate when it reports them in a future Integrated Report cycle.
Water level: 365-day record
Daily water surface elevation values, feet above the North American Vertical Datum of 1988 (NAVD 88), from USGS gauge 01323500 (Great Sacandaga Lake at Conklingville Ny), shown weekly. Readings are daily-batch snapshots, not real-time conditions.
- Latest reading
- 762.1 ft 1.8500000000000227ft vs 32 days earlier
- 2026-08-15 · Provisional, subject to USGS revision
Water level: 365-day record
Subscribe to water level updates for Great Sacandaga Lake (RSS)
203 of the 363 daily values in this window (56%) are provisional and subject to USGS revision; USGS has approved this gauge's record through 2026-01-22.
Of the 363 daily values in this record, 1 was estimated by USGS rather than measured. USGS marks these individually; approval and estimation are separate judgements and a value can carry both.
Full gauge record: USGS monitoring location 01323500
In context
Where Great Sacandaga 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
24,722 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
2 Longer than most more listed causes than 80% 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 Great Sacandaga Lake. 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, Great Sacandaga Lake ranks 51st by listed-cause count (2 listed causes) and 4th by assessed size among the 392 with an area filed; it sits in the not-supporting set (563 statewide) . Its listed causes include Mercury, which also appears among New York's most-filed impairment causes (led by pH). It also lists Flow Alteration-Changes in Depth and Flow Velocity, 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 |
| Lake Champlain, Main Lake, North Not Supporting | 18,335 |
Peers near Great Sacandaga Lake's size or cause load
Similar assessed acres
Nearest filed extents (24,722 acres here).
- Ouachita Lake · 24,695 acres · AR
- Carlyle · 24,580 acres · IL
- Lake C. W. McConaughy · 24,868 acres · NE
- Almanor Lake · 24,897 acres · CA
Similar cause load
Nearest listed-cause counts (2 here). Peers already in the acreage column are omitted.
- 12th St. Beach · 2 causes · IL
- 31st St. Beach · 2 causes · IL
- 49th St. Beach · 2 causes · IL
- 57th St. Beach · 2 causes · IL
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
- Water levels shown are daily snapshots. Seasonal drawdown and datum conventions matter when comparing levels. How to read level data
- 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 NY1104-0024. 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.