Lake Thirty
Lake Thirty in Barron County, Wisconsin is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 4.8 ft visibility. Phosphorus: 19.4 µg/L. Maximum depth: 27 ft. Surface area: 75 acres.
- Clarity
- 4.8 ft
- Max depth
- 27 ft
- Area
- 75 acres
- Trend
- → Stable
- Public access
- Yes
Next lake in Barron County
Why Lake Thirty has no grade
We grade a lake only when its monitoring record clears the evidence bar: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Lake Thirty, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). Sampling here has recorded water clarity and phosphorus, but not algae (chlorophyll-a).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by WI DNR and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Lake Thirty is a 75-acre lake in Barron County, Wisconsin with a maximum depth of 27 feet. The lake supports 3 documented fish species including Panfish, Largemouth Bass, and Northern Pike. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2022-07-28. Grade methodology: LakeGrade methodology.
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Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Lake Thirty
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Murky, only visible to about 4.8 ft. Phosphorus level: 19.4 µg/L. Trophic State Index: 51.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4.8 ft | Not graded |
| Phosphorus | 19.4 µg/L | Not graded |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 51 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Lake Thirty
Compare lakeside cabins, hotels, and vacation rentals near Lake Thirty in Barron County, Wisconsin — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
Top-rated places to stay near Lake Thirty
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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 27 ft |
| Surface Area | 75 acres |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Lake ThirtyPublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Lake Thirty
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. 1 station on file (most recent sample 2022).
Fish Species (DNR-rated)
Water Quality Trend: → Stable
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.053 m/yr | 7 |
| Phosphorus | → Stable | -0.22 µg/L/yr | 6 |
EPA Impairment Status
Lake Thirty is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5R).
Causes of impairment
Source: EPA ATTAINS assessment unit WI10004486 · Official waterbody report
Graded lakes near Lake Thirty
Lake Thirty has no grade, but these lakes within a short drive do.
Nearby Lakes in Barron County
Frequently asked questions about Lake Thirty
What is the water quality grade for Lake Thirty?
- Lake Thirty in Barron County, Wisconsin is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 4.8 ft visibility. Phosphorus: 19.4 µg/L. Maximum depth: 27 ft. Surface area: 75 acres.
Is Lake Thirty safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Lake Thirty is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
How deep is Lake Thirty?
- Lake Thirty has a maximum depth of 27 feet. The lake covers 75 acres.
What fish are in Lake Thirty?
- Fish species found in Lake Thirty include Panfish, Largemouth Bass, Northern Pike. Lake Thirty is located in Barron County, Wisconsin.
Are there boat ramps on Lake Thirty?
- Lake Thirty has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Lake Thirty. Public access is listed as yes.
Explore Lake Thirty across LakeGrade
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Where this data comes from
3 measurements from 1 monitoring station, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX3 samples · 2022
Analytical methods
- Phosphorus by Colorimetry
- Turbidity in Water
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Fish and recreation data from Wisconsin DNR Lakes
Named boat-access points from the USGS National Boat Ramps inventory