Round Lake
Round Lake in Anoka County, Minnesota has a water quality grade of A (Excellent). Water clarity: 8.9 ft visibility. Phosphorus: 19 µg/L. Chlorophyll-a (algae): 5.3 µg/L.
- Clarity
- 8.9 ft
- Typical in August
- 76°F
- Type
- Mesotrophic
- Trend
- ↑ Improving
- Public access
- Yes
- Ice-out
- Mar 22
- Open water
- 250 days
Next lake in Anoka County
Round Lake is a mesotrophic lake in Anoka County, Minnesota. Water quality is graded A based on 2 sampling years through 2025. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 22 other monitored lakes in Anoka County, Round Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-24. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLow algae
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)
Moderate clarity, visible to about 8.9 ft. Phosphorus level: 19 µg/L. Chlorophyll-a: 5.3 µg/L. Trophic State Index: 46.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 8.9 ft | Not graded |
| Phosphorus | 19 µg/L | Good |
| Chlorophyll-a (Algae) | 5.3 µg/L | Good |
| Trophic State Index (TSI) | 46 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Round Lake
Compare lakeside cabins, hotels, and vacation rentals near Round Lake in Anoka 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
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
Round Lake typically sits around 76°F at the surface in August. Summer average is about 75°F. Usually warmest in Jul (about 78°F) and coldest in May (about 67°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 56 field readings (2016–2025) via the EPA Water Quality Portal. See the full Round Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Round Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was high (510,505 cells/mL) on May 9, 2026.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Round LakePublic
Fishing Round Lake
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Round Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Public Water Access Sites — RoundPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: ↑ Improving
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.247 m/yr | 4 |
| Phosphorus | ↑ Improving | -1 µg/L/yr | 3 |
| Chlorophyll-a | → Stable | 0 µg/L/yr | 3 |
Ice Season
Historical ice data from Minnesota DNR (9 observations).
Estimated open water season: 250 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2024-03-01 (2024) | 2020-03-28 (2020) |
| Ice-In | 2018-11-10 (2018) | 2016-12-07 (2016) |
Most recent ice-out: 2024-03-01
County Ranking
Ranked #1 of 23 lakes in Anoka County
Nearby Lakes in Anoka County
Frequently asked questions about Round Lake
What is the water quality grade for Round Lake?
- Round Lake in Anoka County, Minnesota has a water quality grade of A (Excellent). Water clarity: 8.9 ft visibility. Phosphorus: 19 µg/L. Chlorophyll-a (algae): 5.3 µg/L.
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 5.3 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Round Lake?
- Round Lake typically sits around 76°F at the surface in August, from 56 EPA Water Quality Portal field readings (2016–2025). That is a typical value for the month, not a live reading.
How deep is Round Lake?
- The available depth estimate for Round Lake is shallower than its measured water clarity, which cannot be right, so no depth is shown.
When does Round Lake thaw?
- Round Lake typically has ice-out around Mar 22. Ice typically forms around Nov 27. The open water season is approximately 250 days.
Does Round Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Round Lake (clouds, ice, or an off-season gap). The most recent reading was high (510,505 cells/mL). Blue-green algae can appear and clear within days, so check Minnesota's current advisory before swimming.
Are there boat ramps on Round Lake?
- Round Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Round Lake. Public access is listed as yes.
Explore Round Lake across LakeGrade
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Where this data comes from
132 measurements from 1 monitoring station, 2021–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA132 samples · 2021–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- Turbidity, Nephelometric Method
- Turbidity, Probe Method
Monitoring station identifiers (1)
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory
Ice data from Minnesota DNR Climate