Wisconsin Great Lakes waterbody · state assessment record
Lake Superior (186.01 mi)
In Douglas County. Assessment decisions reported by Wisconsin to EPA under Clean Water Act sections 303(d) and 305(b), last assessed in the 2022 reporting cycle.
- 186.01
- Miles of shoreline
- Great Lakes Shoreline
- Water type
This waterbody in one line
Lake Superior, a Great Lakes waterbody in Wisconsin, is assessed as not supporting one or more designated uses, with 3 listed impairment causes in the state's most recent Integrated Report cycle (2022). Its impairment list is among the longest nationally (3 listed causes vs 23,610 assessed lakes). Fish consumption is assessed as not supporting.
- Not Supporting
- overall status
- P5
- Shorter cause list
- Not Supporting
- fish consumption
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 Lake Superior 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 Wisconsin, cause-list rank is the local separator: Lake Superior is 11 of 1,219 indexed units by listed-cause count, toward the top of that state's filed lists.
Every filed use falls short
On the uses this filer ruled on, fish consumption, every determination is Not Supporting. That is a use-by-use reading of the filed record, not a single overall lake grade.
Longer than most cause lists
3 listed causes puts this unit above 90% 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.
Lake Superior: Category 5, TMDL still owed
Category 5 is the Integrated Report band where a TMDL (or equivalent) is still expected for Lake Superior. Read the listed causes and any cleanup actions filed beside them before treating the overall status tile as a finished restoration story.
Overall status: not supporting
The filer's overall status for Lake Superior 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, Wisconsin carries 19,871 filed lake-type waterbodies in the August 2026 extract, and this page renders the assessment record EPA assigned to Lake Superior 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. The latest monitoring Wisconsin filed against this record runs through 2021. For the one definitive verdict on this record, Wisconsin filed the assessment basis as Monitored Data. Those are EPA's own words, not PlainLakes' summary of them. Wisconsin filed its own confidence on the one definitive verdict it rated: Excellent. 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 |
|---|---|---|
| Fish Consumption | Fish-consumption or fishery | Not Supporting Filer confidence: Excellent |
| Fish and Aquatic Life | Aquatic-life or related | Not Assessed |
| Public Health and Welfare | Recreation | Not Assessed |
| Recreation | Recreation | Not Assessed |
| Wildlife | Aquatic-life or related | Not Assessed |
The record
Listed impairment causes
Causes the state listed as impairing designated uses of this Great Lakes waterbody, with the cycle each was first listed and the Clean Water Act action recorded against it.
| Cause | Affected uses | First listed | Cleanup standing |
|---|---|---|---|
| Polychlorinated Biphenyls (PCBs) | Fish Consumption | 1998 | TMDL priority: Low |
| Mercury | Fish Consumption | 2006 | TMDL priority: Low |
| Perfluorooctane Sulfonate (PFOS) | Fish Consumption | 2022 | TMDL priority: Low |
Probable sources named by the state
Each source below is listed under the cause the state filed it against, and carries the word the state filed with it — confirmed, or suspected.
- Polychlorinated Biphenyls (PCBs)
- Contaminated Sediments (confirmed)
- Mercury
- Atmospheric Deposition - Toxics (confirmed) Contaminated Sediments (confirmed)
- Perfluorooctane Sulfonate (PFOS)
- Non-Point Source (suspected)
Reading the record
Where Lake Superior sits among peers
2% of Wisconsin's lakes assessed this deeply also had no use supported
Wisconsin ruled definitively on a single designated use at Lake Superior and found it not supported. The dataset shows 3,571 Wisconsin lakes judged to that same depth.
Wisconsin's assessed lakes are most often judged on 1 use, as this one was.
Computed share from EPA ATTAINS filed records, not an official EPA rating or safety grade.
| 1 | 2 | 3 | 4 | 5+ | |
|---|---|---|---|---|---|
| All supported | 3.5k | 609 | 121 | 1 | 1 |
| Mixed | Not possible | 118 | 112 | 2 | 0 |
| None supported | 78 (this record) | 162 | 20 | 1 | 0 |
Ringed cell: Lake Superior. Source: EPA ATTAINS, Reporting cycles 1987–2026.
Scale and rank
Lake Superior is one of 19,871 lake-type waterbodies reported to EPA from Wisconsin, and one of 1,219 whose reported record carries enough populated assessment or gauge data for this site to list and index it. Wisconsin reports this unit as 186.01 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 recreation verdict and a definitive aquatic-life verdict for this record; those fields populate when it reports them in a future Integrated Report cycle.
Why no water-level record
Lake Superior has no daily USGS water-level or reservoir-storage series on this page because NWIS lists a lake monitoring site named for the waterbody, but the site is not active, and PlainLakes ingests only the active inventory, so there is no series to attach. How PlainLakes links gauges.
In context
Where Lake Superior sits nationally
Listed causes vs waterbodies carrying a verdict
How many impairment causes U.S. waterbodies with a reported verdict carry
3 Longer than most more listed causes than 90% 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 Lake Superior. Hover or tap any bar for its full count and share.
In context
Wisconsin context
ATTAINS carries 19,871 lake-type waterbodies in Wisconsin, 493 assessed as not supporting at least one use and 4,225 fully supporting. Among the 1,219 indexed units there, Lake Superior ranks 11th by listed-cause count (3 listed causes) ; it sits in the not-supporting set (493 statewide) . Its listed causes include Mercury and Perfluorooctane Sulfonate (PFOS), which also appear among Wisconsin's most-filed impairment causes (led by Phosphorus, Total). It also lists Polychlorinated Biphenyls (PCBs), outside that top-five list.
| Other large assessed lakes in Wisconsin | Assessed acres |
|---|---|
| Lake Winnebago Not Supporting | 131,942 |
| Lake Pepin Not Supporting | 25,503 |
| Petenwell Lake Not Supporting | 23,001 |
| Lake Poygan Not Supporting | 14,024 |
| Lake Chippewa Fully Supporting | 13,616 |
| Turtle Flambeau Flowage Not Supporting | 12,943 |
Lakes near Lake Superior's cause load
Similar cause load
Nearest listed-cause counts (3 here). Peers already in the acreage column are omitted.
- 67th St. Beach · 3 causes · IL
- Abiquiu Reservoir · 3 causes · NM
- Absecon Creek (AC Reserviors) (gage to SB) · 3 causes · NJ
- Absecon Creek (below gage) · 3 causes · NJ
What to do with this record
- The fish-consumption use is assessed as not supporting. Before eating fish from this Great Lakes waterbody, check your state fish-advisory program for species-specific meal limits. 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 WI10008955. 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.