Kansas lake · state assessment record
Osage City Reservoir
Assessment decisions reported by Kansas to EPA under Clean Water Act sections 303(d) and 305(b), last assessed in the 2024 reporting cycle.
- 47
- Assessed acres
- Lake
- Water type
This waterbody in one line
Osage City Reservoir, a lake in Kansas, is assessed as not supporting one or more designated uses, with one listed impairment cause in the state's most recent Integrated Report cycle (2024). By assessed acreage it sits above the national median by assessed acreage (38,628 lakes); its impairment list is among the longest nationally (one listed cause vs 23,610 assessed lakes). Aquatic life is assessed as not supporting.
- Not Supporting
- overall status
- P53
- Assessed size nationally
- P20
- 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 Osage City Reservoir 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 Kansas, cause-list rank 142 of 304 is mid-pack, the state peer table is not driven by an extreme list length here.
No ruled-on use clears the bar
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.
Osage City Reservoir: Category 4A reading
Category 4A means a TMDL (or equivalent) is already approved for the impairment on Osage City Reservoir. The remaining work is implementation and tracking, read the cleanup-standing and cause rows for what the state already committed to address.
Overall status: not supporting
The filer's overall status for Osage City Reservoir is Not Supporting. That tile summarizes the assessment unit; the designated-use rows and cause list are the evidence behind it.
Mid-pack inside Kansas
Size rank 138 of 304 inside Kansas is mid-pack; the national percentile is the better scale comparison for this unit.
According to the U.S. Environmental Protection Agency's ATTAINS program, Kansas carries 328 filed lake-type waterbodies in the August 2026 extract, and this page renders the assessment record EPA assigned to Osage City Reservoir 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 |
|---|---|---|
| Agricultural Supply Use--Irrigation | Other | Fully Supporting |
| Aquatic Life Use | Aquatic-life or related | Not Supporting |
| Domestic Water Supply | Drinking-water supply designation | Not Supporting |
| Primary Contact Recreation | Recreation | Not Supporting |
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 |
|---|---|---|---|
| Eutrophication | Aquatic Life Use, Domestic Water Supply, Primary Contact Recreation | 2002 | TMDL approved |
Reading the record
Osage City Reservoir: Category 4A reading
4A Category 4A: impaired, TMDL completed
Kansas 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
Osage City Reservoir is one of 328 lake-type waterbodies reported to EPA from Kansas, and one of 304 whose reported record carries enough populated assessment or gauge data for this site to list and index it. At 47 assessed acres it ranks 18,095th 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 18,094 lakes with a larger one.
Awaiting a filing
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 Osage City Reservoir 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
47 Top 47% larger than 53% 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
1 Longer than most more listed causes than 49% 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 Osage City Reservoir. Hover or tap any bar for its full count and share.
In context
Kansas context
ATTAINS carries 328 lake-type waterbodies in Kansas, 241 assessed as not supporting at least one use and 77 fully supporting. Among the 304 indexed units there, Osage City Reservoir ranks 142nd by listed-cause count (one listed cause) and 138th by assessed size among the 304 with an area filed; it sits in the not-supporting set (241 statewide) . Its listed causes include Eutrophication, which also appears among Kansas's most-filed impairment causes (led by Eutrophication).
| Other large assessed lakes in Kansas | Assessed acres |
|---|---|
| Milford Lake Not Supporting | 16,000 |
| Tuttle Creek Lake Not Supporting | 15,380 |
| Waconda Lake Not Supporting | 12,602 |
| Perry Lake Not Supporting | 12,200 |
| Cheney Lake Not Supporting | 9,550 |
| John Redmond Lake Not Supporting | 9,400 |
Peers near Osage City Reservoir's size or cause load
Similar assessed acres
Nearest filed extents (47 acres here).
- Bennitt Lake · 47 acres · MO
- Bug · 47 acres · MN
- Byrd Lake · 47 acres · TN
- College Pond · 47 acres · MA
Similar cause load
Nearest listed-cause counts (1 here). Peers already in the acreage column are omitted.
- Aaron · 1 causes · MN
- Aaron River Reservoir · 1 causes · MA
- Abbotts Creek (including Lexington-Thomasville Water Supply Reservoir at normal reservoir elevation, Tom-A-Lex Lake) · 1 causes · NC
- Abeniki Lake · 1 causes · NH
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 KS-LM066101. 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.