Koonz Lake
Shawano County, Wisconsin20 acresView mapDirections
Wisconsin DNR publishes the water-quality measurements for Koonz Lake. Here is what has been measured.
- Mesotrophic
- 40 ft max depth
- Public access
Koonz Lake in Shawano County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. 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.
Wisconsin DNR lists Largemouth Bass as common on Koonz Lake. DNR survey details →
Koonz Lake is a 20-acre mesotrophic lake in Shawano County, Wisconsin with a maximum depth of 40 feet. 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. Methodology: how these readings are compared.
What Koonz Lake is good for
From access and monitoring records, not editorial picks.
- Clear water10.8 ft of visibility
- Boat launch1 documented ramp
- Fishing4 species recorded
- Deep water40 ft surveyed max depth
Swimming conditions
Readings onlyLow algae
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Koonz Lake is safe to swim in today is a call for the Wisconsin Department of Natural Resources and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Koonz Lake
These are the measurements Wisconsin DNR publishes for Koonz Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Good clarity, visible to about 10.8 ft. Phosphorus 17 µg/L. Chlorophyll-a 1.7 µg/L. TSI 41.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 10.8ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 17µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 1.7µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 41 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Koonz Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Koonz Lake typically sits around 66°F at the surface in October. 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.
Column height runs from this lake’s coldest month (49°F) to its warmest (75°F).
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 →
Wisconsin DNR lists Largemouth Bass as common on Koonz Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Koonz Lake’s water-quality measurements separately, and the water-quality trend over 7 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
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)
Lake Details
Max depth
40 ft
Surface area
20 acres
Public access
Yes
Listed by Wisconsin DNR
Recreation & Access
- Koonz LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays 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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Follow Koonz Lake’s readings
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Fish Species
Click a species to see every 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.
Water Quality Trend: Improving
Based on 7 years of monitoring (2020–2026).
Water clarity
Improving6 years
Phosphorus
Stable-0.24 µg/L/yr7 years
Chlorophyll-a
Improving-0.48 µg/L/yr2 years
Nearby Lakes in Shawano County
Frequently asked questions about Koonz Lake
Where is Koonz Lake?
- Koonz Lake is a lake in Shawano County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Koonz Lake?
- Koonz Lake in Shawano County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. 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?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Koonz Lake?
- Koonz Lake typically sits around 66°F at the surface in October, 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.
What did the DNR fisheries survey find at Koonz Lake?
- Wisconsin DNR lists Largemouth Bass as common on Koonz Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Koonz Lake’s water-quality measurements separately, and the water-quality trend over 7 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
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.
Can I fish at Koonz Lake?
- Koonz Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Wisconsin's fish and wildlife agency, so check its current regulations before you go.
Explore Koonz Lake across LakeQuality
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Species activity outlook by water temperature and season
Where to stay at Wisconsin's top lakes, each with its readings
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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)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Fish and recreation data from Wisconsin DNR Lakes
Named boat-access points from the USGS National Boat Ramps inventory