Koonz Lake
Koonz Lake in Shawano County, Wisconsin has a water quality grade of A (Excellent). Water clarity: 10.8 ft visibility. Phosphorus: 17 µg/L. Chlorophyll-a (algae): 1.7 µg/L. Maximum depth: 40 ft. Surface area: 20 acres.
- Clarity
- 10.8 ft
- Typical in August
- 75°F
- Max depth
- 40 ft
- Area
- 20 acres
- Type
- Mesotrophic
- Trend
- ↑ Improving
- Public access
- Yes
Next lake in Shawano County
Koonz Lake is a 20-acre mesotrophic lake in Shawano County, Wisconsin with a maximum depth of 40 feet. Water quality is graded A based on 2 sampling years through 2025. Overall water quality is improving over recent sampling years. The lake supports 4 documented fish species including Panfish, Largemouth Bass, and Northern Pike. Public access is available with 1 public boat landing. Compared to the 20 other monitored lakes in Shawano County, Koonz Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2025-10-07. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLow algae
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A (Excellent)
Good clarity, visible to about 10.8 ft. Phosphorus level: 17 µg/L. Chlorophyll-a: 1.7 µg/L. Trophic State Index: 41.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10.8 ft | Not graded |
| Phosphorus | 17 µg/L | Good |
| Chlorophyll-a (Algae) | 1.7 µg/L | Good |
| Trophic State Index (TSI) | 41 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Koonz Lake
Compare lakeside cabins, hotels, and vacation rentals near Koonz Lake in Shawano 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 Koonz Lake
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Water Temperature
Koonz Lake typically sits around 75°F at the surface in August. Summer average is about 66°F. Usually warmest in Aug (about 75°F) and coldest in May (about 49°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 138 field readings (2025–2025) via the EPA Water Quality Portal. See the full Koonz Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 40 ft |
| Surface Area | 20 acres |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Koonz LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Koonz Lake
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. Monitored by volunteers since 1991. 1 station on file (most recent sample 2025).
Fish Species (DNR-rated)
DNR Reports & Resources
Wisconsin DNR Fisheries scientists publish multi-year survey reports for Koonz Lake covering fish populations, stocking, water quality, and management. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- 2025Koonz and Beaulieu lakes shocking survey, 2025Fisheries Survey · WI DNR · 2025 (PDF)
Water Quality Trend: ↑ Improving
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.736 m/yr | 6 |
| Phosphorus | → Stable | -0.24 µg/L/yr | 7 |
| Chlorophyll-a | ↑ Improving | -0.48 µg/L/yr | 2 |
County Ranking
Ranked #2 of 21 lakes in Shawano County
Nearby Lakes in Shawano County
Frequently asked questions about Koonz Lake
What is the water quality grade for Koonz Lake?
- Koonz Lake in Shawano County, Wisconsin has a water quality grade of A (Excellent). Water clarity: 10.8 ft visibility. Phosphorus: 17 µg/L. Chlorophyll-a (algae): 1.7 µg/L. Maximum depth: 40 ft. Surface area: 20 acres.
Is Koonz Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Koonz Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 1.7 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Koonz Lake?
- Koonz Lake typically sits around 75°F at the surface in August, from 138 EPA Water Quality Portal field readings (2025–2025). That is a typical value for the month, not a live reading.
How deep is Koonz Lake?
- Koonz Lake has a maximum depth of 40 feet. The lake covers 20 acres.
What fish are in Koonz Lake?
- Fish species found in Koonz Lake include Panfish, Largemouth Bass, Northern Pike, Walleye. Koonz Lake is located in Shawano County, Wisconsin.
Are there boat ramps on Koonz Lake?
- Koonz Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Koonz Lake. Public access is listed as yes.
Explore Koonz Lake across LakeGrade
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Where this data comes from
122 measurements from 2 monitoring stations, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Stockbridge_Munsee Community
STOCKBRIDGE_MUNSEE78 samples · 2021–2025 - Wisconsin Department of Natural Resources
WIDNR_WQX44 samples · 2020–2025
Analytical methods
- 4500 P E ~ Phosphorus in Water by Colorimetry- Ascorbic Acid Method
- Phosphorus in Water by Colorimetry- Ascorbic Acid Method
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (2)
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
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