Round Island Lake
Round Island Lake in Lake County, Minnesota has a water quality grade of C (Fair). Phosphorus: 34 µg/L. Maximum depth: 4 ft. Surface area: 54.82 acres.
- Max depth
- 4 ft
- Area
- 55 acres
- Type
- Eutrophic
- Trend
- ↑ Improving
- Public access
- No
Next lake in Lake County
Round Island Lake is a 55-acre productive, nutrient-rich eutrophic lake in Lake County, Minnesota with a maximum depth of 4 feet. Water quality is graded C based on 1 sampling years through 2025. Overall water quality is improving over recent sampling years. Limited fish-species data available. No public access — the lake is private or restricted. Compared to the 34 other monitored lakes in Lake County, Round Island Lake ranks #35 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-07-16. Grade methodology: LakeGrade methodology.
Watch Round Island Lake water quality
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Swimming Safety
Grade onlyLimited data
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.
Generally safe for swimming, moderate water quality
Water Quality Grade: C (Fair)
No clarity data. Phosphorus level: 34 µg/L. Trophic State Index: 55.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 34 µg/L | Fair |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 55 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Round Island Lake
Compare lakeside cabins, hotels, and vacation rentals near Round Island Lake in Lake 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 Round Island Lake
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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 4 ft |
| Surface Area | 55 acres |
| Shoreline Length | 1.6 mi |
| Littoral Zone | 100% |
| Public Access | No |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Fishing Round Island Lake
DNR Fisheries Survey Summary
1 survey on file from MN DNR Fisheries. Most recent: 1983-06-27 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Yellow Perch | 17.25 | 0.14 lb |
| White Sucker | 2.50 | 0.63 lb |
| Walleye | 0.25 | 0.1 lb |
| Northern Pike | 0.25 | 1.5 lb |
CPUE = catch per unit effort, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE = more abundant in standardized sampling.
From the 1983-06-27 survey
The fish population is dominated by Yellow Perch, various minnows and White Sucker. Two Northern Pike and one Walleye were sampled. The Walleye is most likely a migrant from Delay Lake.
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Round Island Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — Round IslandFisheries Lake Survey · MN DNR LakeFinder
Water Quality Trend: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.06 m/yr | 6 |
| Phosphorus | ↑ Improving | -10 µg/L/yr | 3 |
EPA Impairment Status
Round 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 MN38-0415-00 · Official waterbody report · Matched by proximity (1.75 km)
County Ranking
Ranked #35 of 35 lakes in Lake County
Nearby Lakes in Lake County
Frequently asked questions about Round Island Lake
What is the water quality grade for Round Island Lake?
- Round Island Lake in Lake County, Minnesota has a water quality grade of C (Fair). Phosphorus: 34 µg/L. Maximum depth: 4 ft. Surface area: 54.82 acres.
Is Round Island Lake safe to swim in?
- Generally safe for swimming, moderate water quality. Round Island Lake has a water quality grade of C (Fair). Always check local health department advisories before swimming.
How deep is Round Island Lake?
- Round Island Lake has a maximum depth of 4 feet. The lake covers 54.82 acres.
Explore Round Island Lake across LakeGrade
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Where this data comes from
6 measurements from 2 monitoring stations, 2023–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA6 samples · 2023–2025
Analytical methods
- Phosphorus by Two Reagent Colorimetry
- Phosphorus by Colorimetry
- Turbidity by Nephelometry
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder