Green Lake
Green Lake in Beltrami County, Minnesota has a water quality grade of A (Excellent). Water clarity: 18.5 ft visibility. Phosphorus: 7 µg/L. Chlorophyll-a (algae): 1.6 µg/L.
- Clarity
- 18.5 ft
- Typical in August
- 74°F
- Type
- Oligotrophic
- Trend
- ↑ Improving
Next lake in Beltrami County
Green Lake is a cold, clear oligotrophic lake in Beltrami County, Minnesota. Water quality is graded A based on 2 sampling years through 2025. Overall water quality is improving over recent sampling years. Compared to the 84 other monitored lakes in Beltrami County, Green Lake ranks #13 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-25. Grade methodology: LakeGrade methodology.
Watch Green Lake water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
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)
Crystal clear, you can see 18.5 ft down. Phosphorus level: 7 µg/L. Chlorophyll-a: 1.6 µg/L. Trophic State Index: 34.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 18.5 ft | Not graded |
| Phosphorus | 7 µg/L | Good |
| Chlorophyll-a (Algae) | 1.6 µg/L | Good |
| Trophic State Index (TSI) | 34 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Green Lake
Compare lakeside cabins, hotels, and vacation rentals near Green Lake in Beltrami 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 Green 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
Green Lake typically sits around 74°F at the surface in August. Summer average is about 72°F. Usually warmest in Jul (about 77°F) and coldest in Jan (about 34°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 85 field readings (2010–2025) via the EPA Water Quality Portal. See the full Green Lake water temperature breakdown →
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Fishing Green Lake
Water Quality Trend: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.4 m/yr | 6 |
| Phosphorus | ↑ Improving | -0.49 µg/L/yr | 6 |
| Chlorophyll-a | ↑ Improving | -0.16 µg/L/yr | 6 |
County Ranking
Ranked #13 of 85 lakes in Beltrami County
Nearby Lakes in Beltrami County
Frequently asked questions about Green Lake
What is the water quality grade for Green Lake?
- Green Lake in Beltrami County, Minnesota has a water quality grade of A (Excellent). Water clarity: 18.5 ft visibility. Phosphorus: 7 µg/L. Chlorophyll-a (algae): 1.6 µg/L.
Is Green Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Green 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 Green Lake?
- Green Lake typically sits around 74°F at the surface in August, from 85 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.
How deep is Green Lake?
- The available depth estimate for Green Lake is shallower than its measured water clarity, which cannot be right, so no depth is shown.
Explore Green Lake across LakeGrade
Fish species and top-graded lakes across Minnesota
Fish species and best lakes in Beltrami County
Species activity outlook by water temperature and season
Where to stay at Minnesota's top lakes, each with its grade
Lakes in the Mississippi Headwaters, ranked by water quality
Low nutrients, clear water, excellent for swimming
Minnesota's cleanest and most-polluted lakes, ranked
More Minnesota Lake Rankings
State Parks Near Green Lake
Other Grade A Lakes in Minnesota
Oligotrophic Lakes in Minnesota
Where this data comes from
96 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Red Lake DNR
REDLAKE_WQX96 samples · 2020–2025
Analytical methods
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- Turbidity by Nephelometry
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)