Michigan lake shoreline · state assessment record
Oasis Lake County Park Beach
Assessment decisions reported by Michigan to EPA under Clean Water Act sections 303(d) and 305(b), last assessed in the 2022 reporting cycle.
- 0.20
- Miles of shoreline
- Inland Lake Shoreline
- Water type
This waterbody in one line
Oasis Lake County Park Beach, a lake shoreline in Michigan, is assessed as not supporting one or more designated uses, with one listed impairment cause in the state's most recent Integrated Report cycle (2022). Its impairment list is among the longest nationally (one listed cause vs 23,610 assessed lakes).
- Not Supporting
- overall status
- P20
- 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 Oasis Lake County Park Beach 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: in-state cause rank
Inside Michigan, this unit sits toward the short-list end: cause-list rank 648 of 776 indexed units.
Every filed use falls short
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.
Oasis Lake County Park Beach: Category 4A reading
Category 4A means a TMDL (or equivalent) is already approved for the impairment on Oasis Lake County Park Beach. 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 Oasis Lake County Park Beach is Not Supporting. That tile summarizes the assessment unit; the designated-use rows and cause list are the evidence behind it.
Typical cause-list length
1 listed cause is a middle-tercile list length among assessed lake-type units. Look to IR category and use outcomes for the distinctive reading.
According to the U.S. Environmental Protection Agency's ATTAINS program, Michigan carries 4,307 filed lake-type waterbodies in the August 2026 extract, and this page renders the assessment record EPA assigned to Oasis Lake County Park Beach 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. For the definitive verdicts on this record, Michigan filed the assessment basis as Monitored Data. Those are EPA's own words, not PlainLakes' summary of them. Michigan filed its own confidence on the 5 definitive verdicts it rated: Good. That rating is the filer's, in EPA's own field, and EPA publishes no definition of the four words it offers.
| Designated use | Group | Verdict |
|---|---|---|
| Agriculture | Other | Fully Supporting Filer confidence: Good |
| Industrial Water Supply | Other | Fully Supporting Filer confidence: Good |
| Navigation | Other | Fully Supporting Filer confidence: Good |
| Partial Body Contact Recreation | Recreation | Fully Supporting Filer confidence: Good |
| Total Body Contact Recreation | Recreation | Not Supporting Filer confidence: Good |
| Cold Water Fishery | Aquatic-life or related | Not Assessed |
| Fish Consumption | Fish-consumption or fishery | Not Assessed |
| Other Indigenous Aquatic Life and Wildlife | Aquatic-life or related | Not Assessed |
| Warm Water Fishery | Aquatic-life or related | Not Assessed |
The record
Listed impairment causes
Causes the state listed as impairing designated uses of this lake shoreline, with the cycle each was first listed and the Clean Water Act action recorded against it.
| Cause | Affected uses | First listed | Cleanup standing |
|---|---|---|---|
| Escherichia coli (E. coli) | Total Body Contact Recreation Also assessed as meeting: Partial Body Contact Recreation | 2024 | TMDL approved |
Probable sources
Michigan listed the source of the impairment as unknown. That is the state's own filed value, not a gap in this record: the cause has been identified, the origin has not.
Reading the record
Oasis Lake County Park Beach: Category 4A reading
4A Category 4A: impaired, TMDL completed
Michigan 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
Oasis Lake County Park Beach is one of 4,307 lake-type waterbodies reported to EPA from Michigan, and one of 776 whose reported record carries enough populated assessment or gauge data for this site to list and index it. Michigan reports this unit as 0.20 miles of shoreline rather than a surface area, so it is not ranked against the acreage figures elsewhere on this site.
Awaiting a filing
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 Oasis Lake County Park Beach sits nationally
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 Oasis Lake County Park Beach. Hover or tap any bar for its full count and share.
In context
Michigan context
ATTAINS carries 4,307 lake-type waterbodies in Michigan, 807 assessed as not supporting at least one use and 3,457 fully supporting. Among the 776 indexed units there, Oasis Lake County Park Beach ranks 648th by listed-cause count (one listed cause) ; it sits in the not-supporting set (807 statewide) . Its listed causes include Escherichia coli (E. coli), which also appears among Michigan's most-filed impairment causes (led by Mercury in Fish Tissue).
| Other large assessed lakes in Michigan | Assessed acres |
|---|---|
| Lake Huron (Michigan Jurisdiction) Not Supporting | 5,815,360 |
| Lake Michigan South of Frankfort (Michigan Jurisdiction) Not Supporting | 5,665,920 |
| St. Marys River Not Supporting | 129,983 |
| Lake St. Clair (Michigan Jurisdiction) Not Supporting | 103,616 |
| Lake Erie (Michigan Jurisdiction) Not Supporting | 71,680 |
| Houghton Lake Not Supporting | 20,066 |
Lakes near Oasis Lake County Park Beach's cause load
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 MI040801020103-01. 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.