New York reservoir · state assessment record
Owasco 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. 2 determinations below were filed by EPA rather than by New York.
- 6,797
- Assessed acres
- Lake / Reservoir / Pond
- Water type
- 712.1 ft
- Water Surface Elevation (provisional)
This waterbody in one line
Owasco 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
- P99
- Assessed size nationally
- P10
- Shorter cause list
Assessment verdicts are the state agency's and EPA'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 Owasco Lake 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 Owasco Lake nationally is assessed size: 6,797 acres, larger than 99% of the 38,628 lake-type units with an area on file.
Every ruled-on use is not supporting
On the uses this filer ruled on, recreation, every determination is Not Supporting. That is a use-by-use reading of the filed record, not a single overall lake grade.
Owasco Lake: Category 5, TMDL still owed
Category 5 is the Integrated Report band where a TMDL (or equivalent) is still expected for Owasco Lake. Read the listed causes and any cleanup actions filed beside them before treating the overall status tile as a finished restoration story.
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 Owasco 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 Owasco 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 and EPA's definitive verdicts; other entries mean the use was not conclusively assessed in this cycle.
| Designated use | Group | Verdict |
|---|---|---|
| Primary Contact Recreation | Recreation | Not Supporting |
| Secondary Contact Recreation | Recreation | Not Supporting |
| Water Supply | Drinking-water supply designation | Not Supporting Filed by EPA |
| Fishing | Aquatic-life or related | 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 |
|---|---|---|---|
| Fecal Coliform | Secondary Contact Recreation, Primary Contact Recreation Also assessed as meeting: Fishing, Water Supply | 1998 | TMDL priority: High |
| Harmful Algal Blooms Filed by EPA | Primary Contact Recreation, Secondary Contact Recreation, Water Supply Also assessed as meeting: Fishing | 2022 | TMDL priority: Medium |
Reading the record
Cleanup queue for Owasco Lake
1 listed cause ranked High in the TMDL queue, still without a plan
New York ranked Fecal Coliform high in its TMDL development queue, and no cleanup plan is on file for that listing yet. That queue rank is the state's own scheduling signal, not an EPA national rule.
A High ranking names a position in the state's plan-writing queue; it is not a measure of how impaired the water is. How listing and cleanup work.
Scale and rank
Owasco 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 6,797 assessed acres it ranks 470th 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 469 lakes with a larger one.
Water level
A USGS gauge tracks this reservoir's water surface elevation daily, and the latest reading is 0.00 ft above the reading 30 days earlier, against a 365-day observed range of 3.7 ft. 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.
Water level: 365-day record
Daily water surface elevation values, feet above the North American Vertical Datum of 1988 (NAVD 88), from USGS gauge 04235396 (Owasco Lake Near Auburn Ny), shown weekly. Readings are daily-batch snapshots, not real-time conditions.
- Latest reading
- 712.1 ft 0ft vs 30 days earlier
- 2026-08-15 · Provisional, subject to USGS revision
Water level: 365-day record
Subscribe to water level updates for Owasco Lake (RSS)
90 of the 365 daily values in this window (25%) are provisional and subject to USGS revision; USGS has approved this gauge's record through 2026-05-17.
Of the 365 daily values in this record, 4 were 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 04235396
In context
Where Owasco 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
6,797 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 Owasco 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, Owasco Lake ranks 53rd by listed-cause count (2 listed causes) and 14th by assessed size among the 392 with an area filed; it sits in the not-supporting set (563 statewide) . Its listed causes (Fecal Coliform and Harmful Algal Blooms) sit outside New York's top-five list, which is led by pH.
| 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 Owasco Lake's size or cause load
Similar assessed acres
Nearest filed extents (6,797 acres here).
- Cedar Bluff Lake · 6,800 acres · KS
- Ray Roberts Lake · 6,807 acres · TX
- Fletcher Pond · 6,814 acres · MI
- Horsehead Lake · 6,778 acres · ND
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 NY0706-0009. 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.