Island Lake
Cass County, MinnesotaView mapDirections
Minnesota PCA publishes the water-quality measurements for Island Lake. Here is what has been measured.
- Mesotrophic
- 35 ft max depth
Island Lake in Cass County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 8.2 ft visibility. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 3.9 µg/L.
Island Lake is a mesotrophic lake in Cass County, Minnesota with an estimated average depth of about 35 feet. Overall water quality is declining over recent sampling years. Limited fish-species data available. No public access — the lake is private or restricted. Compared to the 103 other monitored lakes in Cass County, Island Lake ranks #16 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-09-12. Methodology: how these readings are compared.
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 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 Island Lake
These are the measurements Minnesota PCA publishes for 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 8.2 ft. Phosphorus 20 µg/L. Chlorophyll-a 3.9 µg/L. TSI 46.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 8.2ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 20µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 3.9µg/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. | 46 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Island Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Island Lake typically sits around 68°F at the surface in September. Summer average is about 69°F. Usually warmest in Aug (about 71°F) and coldest in May (about 58°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (58°F) to its warmest (71°F).
Typical surface water temperature by month, from 45 field readings (2023–2024) via the EPA Water Quality Portal.
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Island Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Aquatic Plant Report — Island (1475)Aquatic Plant Report · MN DNR LakeFinder
Lake Details
Max depth
~35 ft est.
Public access
No
Listed by Minnesota PCA
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Minnesota has not published bathymetry for Island Lake.
Lake Size & Watershed
Watershed (drainage) area
25 sq mi
HydroLAKES / HydroSHEDS
Surface area
86 acres
HydroLAKES / HydroSHEDS
Shoreline
1.9 mi
HydroLAKES / HydroSHEDS
Elevation
1,319 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Stays via Stay22
Stays near Island Lake
Compare lakeside cabins, hotels, and vacation rentals near Island Lake in Cass County, Minnesota — 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 Island Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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Fishing Island Lake
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.
Water clarity
Worsening2 years
Phosphorus
Worsening+8.5 µg/L/yr2 years
Chlorophyll-a
Improving-0.4 µg/L/yr2 years
Nearby Lakes in Cass County
Frequently asked questions about Island Lake
Where is Island Lake?
- 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 Island Lake?
- Island Lake in Cass County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 8.2 ft visibility. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 3.9 µg/L.
Is 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 Island Lake?
- Island Lake typically sits around 68°F at the surface in September, from 45 EPA Water Quality Portal field readings (2023–2024). That is a typical value for the month, not a live reading.
How deep is Island Lake?
- No published bathymetric survey covers Island Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 35 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Can I fish at Island Lake?
- Public access to Island Lake is listed as no on the lake record, so confirm before you make the trip. 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.
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Where this data comes from
27 measurements from 1 monitoring station, 2023–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA27 samples · 2023–2024
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by 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 size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder