Merrill Lake
St. Louis County, MinnesotaView mapDirections
Minnesota PCA publishes the water-quality measurements for Merrill Lake. Here is what has been measured.
- Limited data
Merrill Lake in St. Louis County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 16 ft visibility.
Merrill Lake is a lake in St. Louis County, Minnesota. Limited fish-species data available. No public access — the lake is private or restricted.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-24. Methodology: how these readings are compared.
The median ice-out date is April 30, which is when the open-water season begins. For a place on the water, look through cabin and lake-house rentals near Merrill Lake on Vrbo. For a hotel or motel room, Booking.com and Expedia both search around the lake.
What Merrill Lake is good for
From access and monitoring records, not editorial picks.
- Clear water16 ft of visibility
- Ice seasonIce-out around Apr 30
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Merrill Lake is safe to swim in today is a call for the Minnesota Pollution Control Agency and the Minnesota DNR and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Merrill Lake
These are the measurements Minnesota PCA publishes for Merrill Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Crystal clear, you can see 16 ft down. TSI 37.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 16ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 37 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Merrill Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Merrill Lake typically sits around 65°F at the surface in September. Summer average is about 72°F. Usually warmest in Jul (about 74°F) and coldest in May (about 62°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (62°F) to its warmest (74°F).
Typical surface water temperature by month, from 16 field readings (2025–2025) via the EPA Water Quality Portal. See the full Merrill Lake water temperature breakdown →
Stays via Stay22
Stays near Merrill Lake
Compare lakeside cabins, hotels, and vacation rentals near Merrill Lake in St. Louis 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 Merrill Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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 →
Follow Merrill Lake’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fishing Merrill Lake
Water Quality Trend: Stable
Based on 6 years of monitoring (2020–2025).
Water clarity
Stable6 years
Ice season
Typical ice-out
Apr 30
Earliest Apr 12, 2015 · Latest May 11, 2013
Typical ice-in
Nov 22
Earliest Nov 15, 2014 · Latest Nov 28, 2015
Most recent ice-out
Apr 12
2015
9 observations · Minnesota PCA ice records
Nearby Lakes in St. Louis County
Frequently asked questions about Merrill Lake
Where is Merrill Lake?
- Merrill Lake is a lake in St. Louis County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Merrill Lake?
- Merrill Lake in St. Louis County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 16 ft visibility.
Is Merrill Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Merrill Lake?
- Merrill Lake typically sits around 65°F at the surface in September, from 16 EPA Water Quality Portal field readings (2025–2025). That is a typical value for the month, not a live reading.
When does Merrill Lake thaw?
- Merrill Lake typically has ice-out around Apr 30. Ice typically forms around Nov 22. The open water season is approximately 206 days.
Can I fish at Merrill Lake?
- Public access to Merrill Lake is listed as no on the lake record, so confirm before you make the trip. Seasons, size and bag limits, and whether you need a license are set by Minnesota's fish and wildlife agency, so check its current regulations before you go.
Explore Merrill Lake across LakeQuality
Fish species and the cleanest lakes across Minnesota
Fish species and best lakes in St. Louis County
Species activity outlook by water temperature and season
Top lakes and where to stay in the Lake Vermilion Area area
Where to stay at Minnesota's top lakes, each with its readings
Lakes in the Lake Superior Basin (MN+WI), ranked by water quality
Lakes in the Rainy Lake Watershed, ranked by water quality
Minnesota's cleanest lakes, ranked on agency measurements
More lakes in Minnesota
State Parks Near Merrill Lake
Other Lakes in Minnesota
Oligotrophic Lakes in Minnesota
Where this data comes from
16 measurements from 1 monitoring station, 2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA16 samples · 2025
Analytical methods
- Field measurement/observation, generic method
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Ice data from Minnesota DNR Climate