Island Lake
Island Lake in Carlton County, Minnesota has a water quality grade of D (Nutrient-rich). Water clarity: 5.1 ft visibility. Phosphorus: 26 µg/L. Chlorophyll-a (algae): 14.7 µg/L. Maximum depth: 22 ft. Surface area: 319.99 acres.
- Clarity
- 5.1 ft
- Max depth
- 22 ft
- Area
- 320 acres
- Type
- Eutrophic
- Trend
- ↑ Improving
- Public access
- Yes
- Ice-out
- Apr 17
- Open water
- 211 days
Grade D measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Island Lake →
Next lake in Carlton County
Island Lake is a 320-acre productive, nutrient-rich eutrophic lake in Carlton County, Minnesota with a maximum depth of 22 feet (9-foot average). Water quality is graded D based on 2 sampling years through 2025. Overall water quality is improving over recent sampling years. The lake supports 14 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 1 public boat landing. Compared to the 21 other monitored lakes in Carlton County, Island Lake ranks #16 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-30. Grade methodology: LakeGrade methodology.
Watch Island Lake water quality
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Swimming Safety
Grade onlyElevated nutrients
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.
Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum
Water Quality Grade: D (Nutrient-rich)
Murky, only visible to about 5.1 ft. Phosphorus level: 26 µg/L. Chlorophyll-a: 14.7 µg/L. Trophic State Index: 54.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5.1 ft | Not graded |
| Phosphorus | 26 µg/L | Fair |
| Chlorophyll-a (Algae) | 14.7 µg/L | Poor |
| Trophic State Index (TSI) | 54 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Island Lake
Compare lakeside cabins, hotels, and vacation rentals near Island Lake in Carlton 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. The water-quality grade measures nutrients and algae, not lodging — cabins and rentals around Island Lake are listed below.
Top-rated places to stay near Island Lake
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Minnesota’s top lakes →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 22 ft |
| Average Depth | 9 ft |
| Surface Area | 320 acres |
| Shoreline Length | 5.1 mi |
| Littoral Zone | 65% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Island LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Island Lake
DNR Fisheries Survey Summary
9 surveys on file from MN DNR Fisheries. Most recent: 2024-07-08 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluegill | 21.34 | 0.25 lb |
| CNM | 9.33 | — |
| Largemouth Bass | 7.86 | 1.06 lb |
| GOS | 6.95 | — |
| Yellow Bass | 4.97 | 0.77 lb |
| JND | 3.25 | — |
CPUE = catch per unit effort, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE = more abundant in standardized sampling.
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
Largemouth Bass
Yellow Bass
From the 2024-07-08 survey
A targeted survey of nearshore fish species in Lower (South) Island Lake was conducted on July 8th, 2024 by Index of Biological Integrity (IBI) Program Staff. Sampling sites were evenly spaced around the lake and each was sampled by backpack electrofishing and seining with a 50-foot, where possible. Backpack…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Island Lake. 4 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — Lower (South) IslandFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Lower (South) Island (0249)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — Lower (South) IslandFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — Lower (South) IslandPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: ↑ Improving
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.003 m/yr | 3 |
| Phosphorus | ↑ Improving | -26.5 µg/L/yr | 2 |
| Chlorophyll-a | ↑ Improving | -15.5 µg/L/yr | 2 |
Ice Season
Historical ice data from Minnesota DNR (10 observations).
Estimated open water season: 211 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2015-04-11 (2015) | 2022-05-04 (2022) |
| Ice-In | 2003-11-02 (2003) | 2006-11-19 (2006) |
Most recent ice-out: 2022-05-04
EPA Impairment Status
Island Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN09-0060-01 · Official waterbody report · Matched by proximity (0.77 km)
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Island Lake under Clean Water Act (NPDES) discharge permits. 2 facilities have a reported Clean Water Act violation in the past three years.
- Cromwell WwtpCromwell · 0.9 mi away · NPDES MN0051101Recent violation
- Premier Horticulture Inc - Black Lake And Wright Bogs - Plant SiteCromwell · 1.9 mi away · NPDES MN0055115Recent violation
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
County Ranking
Ranked #16 of 22 lakes in Carlton County
Nearby Lakes With Higher Grades
Island Lake holds Grade D. One nearby lake has a higher nutrient-and-algae grade — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Carlton County
Frequently asked questions about Island Lake
What is the water quality grade for Island Lake?
- Island Lake in Carlton County, Minnesota has a water quality grade of D (Nutrient-rich). Water clarity: 5.1 ft visibility. Phosphorus: 26 µg/L. Chlorophyll-a (algae): 14.7 µg/L. Maximum depth: 22 ft. Surface area: 319.99 acres.
Is Island Lake safe to swim in?
- Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum. Island Lake has a water quality grade of D (Nutrient-rich). Algae concentration (chlorophyll-a) is 14.7 µg/L. Always check local health department advisories before swimming.
How deep is Island Lake?
- Island Lake has a maximum depth of 22 feet and an average depth of 9 feet. The lake covers 319.99 acres.
What fish are in Island Lake?
- Fish species found in Island Lake include black bullhead, black crappie, bluegill, bowfin (dogfish), brown bullhead, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, rock bass, walleye, white sucker, yellow bullhead, yellow perch. Island Lake is located in Carlton County, Minnesota.
When does Island Lake thaw?
- Island Lake typically has ice-out around Apr 17. Ice typically forms around Nov 14. The open water season is approximately 211 days.
Are there boat ramps on Island Lake?
- Island Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Island Lake. Public access is listed as yes.
Explore Island Lake across LakeGrade
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Where this data comes from
86 measurements from 2 monitoring stations, 2021–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA86 samples · 2021–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- 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
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder
Named boat-access points from the USGS National Boat Ramps inventory
Ice data from Minnesota DNR Climate