Round Lake
Round Lake in Cook County, Minnesota has a water quality grade of A (Excellent). Water clarity: 16.5 ft visibility. Phosphorus: 8.5 µg/L. Chlorophyll-a (algae): 1.6 µg/L. Maximum depth: 45 ft. Surface area: 154.48 acres.
- Clarity
- 16.5 ft
- Typical in August
- 65°F
- Max depth
- 45 ft
- Area
- 154 acres
- Type
- Oligotrophic
- Trend
- ↑ Improving
- Public access
- Yes
Next lake in Cook County
Round Lake is a 154-acre cold, clear oligotrophic lake in Cook County, Minnesota with a maximum depth of 45 feet. Water quality is graded A based on 2 sampling years through 2025. Overall water quality is improving over recent sampling years. The lake supports 5 documented fish species including northern pike, smallmouth bass, and walleye. Public access is available. Compared to the 43 other monitored lakes in Cook County, Round Lake ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-10-03. Grade methodology: LakeGrade methodology.
Watch Round Lake water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
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.
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A (Excellent)
Crystal clear, you can see 16.5 ft down. Phosphorus level: 8.5 µg/L. Chlorophyll-a: 1.6 µg/L. Trophic State Index: 36.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 16.5 ft | Not graded |
| Phosphorus | 8.5 µg/L | Good |
| Chlorophyll-a (Algae) | 1.6 µg/L | Good |
| Trophic State Index (TSI) | 36 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Round Lake
Compare lakeside cabins, hotels, and vacation rentals near Round Lake in Cook 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 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 →
Water Temperature
Round Lake typically sits around 65°F at the surface in August. Summer average is about 63°F. Usually warmest in Jul (about 66°F) and coldest in May (about 53°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 162 field readings (2018–2025) via the EPA Water Quality Portal. See the full Round Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 45 ft |
| Surface Area | 154 acres |
| Shoreline Length | 2.7 mi |
| Littoral Zone | 47% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Round Lake
DNR Fisheries Survey Summary
10 surveys on file from MN DNR Fisheries. Most recent: 2015-07-13 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| SHI | 15.89 | — |
| Spottail Shiner | 4.33 | — |
| Walleye | 3.09 | 1.58 lb |
| Yellow Perch | 2.21 | 0.14 lb |
| Smallmouth Bass | 2.13 | 0.67 lb |
| White Sucker | 1.89 | 2.29 lb |
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.
Spottail Shiner
Walleye
Yellow Perch
Smallmouth Bass
From the 2015-07-13 survey
Round Lake is managed primarily for walleye and smallmouth bass. The current (2014) lake management plan established a long range goal for walleye consisting of a minimum gill net catch of 3.0 fish/set, with some fish over 20 inches present. That plan established a size-based long range goal for smallmouth bass: among…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Round Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — RoundFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — RoundFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — RoundPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.147 m/yr | 6 |
EPA Impairment Status
Round 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 MN16-0606-00 · Official waterbody report
County Ranking
Ranked #3 of 44 lakes in Cook County
Nearby Lakes in Cook County
Frequently asked questions about Round Lake
What is the water quality grade for Round Lake?
- Round Lake in Cook County, Minnesota has a water quality grade of A (Excellent). Water clarity: 16.5 ft visibility. Phosphorus: 8.5 µg/L. Chlorophyll-a (algae): 1.6 µg/L. Maximum depth: 45 ft. Surface area: 154.48 acres.
Is Round Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Round Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 1.6 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Round Lake?
- Round Lake typically sits around 65°F at the surface in August, from 162 EPA Water Quality Portal field readings (2018–2025). That is a typical value for the month, not a live reading.
How deep is Round Lake?
- Round Lake has a maximum depth of 45 feet. The lake covers 154.48 acres.
What fish are in Round Lake?
- Fish species found in Round Lake include northern pike, smallmouth bass, walleye, white sucker, yellow perch. Round Lake is located in Cook County, Minnesota.
Explore Round Lake across LakeGrade
Fish species and top-graded lakes across Minnesota
Fish species and best lakes in Cook County
Species activity outlook by water temperature and season
Where to stay at Minnesota's top lakes, each with its grade
Lakes in the Lake Superior Basin (MN+WI), ranked by water quality
Low nutrients, clear water, excellent for swimming
Minnesota's cleanest and most-polluted lakes, ranked
More Minnesota Lake Rankings
Other Grade A Lakes in Minnesota
Oligotrophic Lakes in Minnesota
Where this data comes from
82 measurements from 2 monitoring stations, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA82 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent 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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder