Three Island Lake
Cass County, Minnesota288 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Three Island Lake. Here is what has been measured.
- Mesotrophic
- 13 ft max depth
- Public access
- Limited data
Three Island Lake in Cass County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 9 ft visibility. Phosphorus: 12 µg/L. Chlorophyll-a (algae): 3.3 µg/L. Maximum depth: 13 ft. Surface area: 287.89 acres.
Minnesota DNR's Standard Survey on July 18, 2022 caught 20.17 northern pike per gill net at Three Island Lake. Length samples in the latest survey that recorded them ran 8–27 inches. DNR survey details →
Three Island Lake is a 288-acre mesotrophic lake in Cass County, Minnesota with a maximum depth of 13 feet. Overall water quality is declining over recent sampling years. The lake supports 8 documented fish species including black crappie, bluegill, and hybrid sunfish. Public access is available with 1 public boat landing. Compared to the 103 other monitored lakes in Cass County, Three Island Lake ranks #40 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2023-09-06. Methodology: how these readings are compared.
What Three Island Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Fishing8 species recorded
Swimming conditions
Readings onlyLimited data
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 Three Island Lake is safe to swim in today is a call for the Minnesota Pollution Control Agency and the Minnesota DNR and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Three Island Lake
These are the measurements Minnesota PCA publishes for Three Island Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Moderate clarity, visible to about 9 ft. Phosphorus 12 µg/L. Chlorophyll-a 3.3 µg/L. TSI 43.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 9ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 12µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 3.3µg/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. | 43 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Three Island Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Three Island Lake typically sits around 72°F at the surface in September. Summer average is about 73°F. Usually warmest in Aug (about 75°F) and coldest in May (about 65°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (65°F) to its warmest (75°F).
Typical surface water temperature by month, from 24 field readings (2010–2023) via the EPA Water Quality Portal. See the full Three Island Lake water temperature breakdown →
Minnesota DNR's Standard Survey on July 18, 2022 caught 20.17 northern pike per gill net at Three Island Lake. Length samples in the latest survey that recorded them ran 8–27 inches.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Three Island Lake’s water-quality measurements separately, and the water-quality trend over 2 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
6 surveys on file from MN DNR Fisheries. Most recent: 2022-07-18 (Standard Survey).
6 surveys on file · most recent 2022-07-18 (Standard Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Bluegill | 15.66 | 2–7 in 2022-07-18 | 0.15 lb |
| Pumpkinseed | 8.59 | 4–7 in 2022-07-18 | 0.22 lb |
| Northern Pike | 6.28 | 8–27 in 2022-07-18 | 1.83 lb |
| Yellow Perch | 5.21 | 5–9 in 2022-07-18 | 0.17 lb |
| Black Crappie | 1.79 | 4–13 in 2022-07-18 | 0.3 lb |
| Walleye | 1.66 | 25–27 in 2006-08-14 | 4.1 lb |
CPUE = catch per unit effort, fish caught per net per set in a standardised survey. It measures abundance, not size, and is not a weekly bite report.
Length Distributions
Number of fish caught at each inch class in the most recent survey that recorded lengths. Red dashed line marks an approximate trophy threshold for that species.
Bluegill
Pumpkinseed
Northern Pike
Yellow Perch
From the 2022-07-18 survey
Three Island is a 288-acre lake with 7 miles of shoreline and a maximum depth of 13 feet located east of Walker, MN. A US Forest Service owned public access is located on the north shore. The DNR has classified Minnesota's lakes into 43 different classes based on physical, chemical and other characteristics. Three…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Three Island Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — Three IslandFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Three Island (1147)Aquatic Plant Report · MN DNR LakeFinder
- —Public Water Access Sites — Three IslandPublic Water Access Sites · MN DNR LakeFinder
Lake Details
Max depth
13 ft
Surface area
288 acres
Shoreline
7.5 mi
Littoral zone
100%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Recreation & Access
- Three Island 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 Three Island Lake
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Top-rated places to stay near Three Island Lake
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Follow Three Island Lake’s readings
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Fish Species
Click a species to see every lake where it is documented.
Fishing Three Island Lake
- → Three Island Lake fishing: DNR survey catch rates, species & stocking
- → Three Island Lake fishing forecast & best times (species outlook + 14-day solunar calendar)
- → Three Island Lake fishing regulations (limits, seasons, special rules)
- → Is it safe to eat fish from Three Island Lake? (mercury & PFAS guide)
Water quality readings over time
2 seasons of samples on record (2023–2024). Calling a direction takes at least 4 years of the same measurement.
Phosphorus
Worsening+2 µg/L/yr2 years
Chlorophyll-a
Worsening+1.3 µg/L/yr2 years
Nearby Lakes in Cass County
Frequently asked questions about Three Island Lake
Where is Three Island Lake?
- Three Island Lake is a lake in Cass County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Three Island Lake?
- Three Island Lake in Cass County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 9 ft visibility. Phosphorus: 12 µg/L. Chlorophyll-a (algae): 3.3 µg/L. Maximum depth: 13 ft. Surface area: 287.89 acres.
Is Three Island 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 Three Island Lake?
- Three Island Lake typically sits around 72°F at the surface in September, from 24 EPA Water Quality Portal field readings (2010–2023). That is a typical value for the month, not a live reading.
How deep is Three Island Lake?
- Three Island Lake has a maximum depth of 13 feet. The lake covers 287.89 acres.
What fish are in Three Island Lake?
- Fish species found in Three Island Lake include black crappie, bluegill, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, white sucker, yellow perch. Three Island Lake is located in Cass County, Minnesota.
What did the DNR fisheries survey find at Three Island Lake?
- Minnesota DNR's Standard Survey on July 18, 2022 caught 20.17 northern pike per gill net at Three Island Lake. Length samples in the latest survey that recorded them ran 8–27 inches. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Three Island Lake’s water-quality measurements separately, and the water-quality trend over 2 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
Are there boat ramps on Three Island Lake?
- Three Island Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Three Island Lake. Public access is listed as yes.
Can I fish at Three Island Lake?
- Three Island 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 Minnesota's fish and wildlife agency, so check its current regulations before you go.
Explore Three Island Lake across LakeQuality
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Where this data comes from
15 measurements from 1 monitoring station, 2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA15 samples · 2023
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (1)
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
Lake details from Minnesota DNR LakeFinder
Named boat-access points from the USGS National Boat Ramps inventory