Best Swimming Lakes in Minnesota: Clearest Water, Lowest Algae (2026)

Best-for-swimming on LakeQuality weights water clarity heavily: a swimmer cares whether they can see their feet, whether the water looks inviting on a 90-degree July day, and whether there is a real harmful-algal-bloom risk. The top Minnesota swimming lake on current data is Rainy Lake.

The swimming-best list filters more aggressively on chlorophyll-a than the cleanest list — even very clear lakes can have harmful-algal-bloom risk under specific conditions, so the swimming ranking is more conservative on that front.

Rank	Lake	County	Advisories & bacteria	Clarity	Algae	Phosphorus	Area
1	Rainy Lake	Cass	Low algae	13.9 ft	1.8 µg/L	11.5 µg/L	129 acres
2	Crane Lake	Otter Tail	Low algae	9 ft	6.4 µg/L	15 µg/L	350 acres
3	Lobster Lake	Douglas	Low algae	13 ft	3.6 µg/L	20.5 µg/L	1,334 acres
4	East Fox Lake	Crow Wing	Low algae	16.4 ft	2.7 µg/L	10 µg/L	241 acres
5	Deep Portage Lake	Cass	Low algae	15.4 ft	1.6 µg/L	9 µg/L	129 acres
6	Clearwater Lake	Cook	Low algae	29 ft	1.3 µg/L	4 µg/L	462 acres
7	Clearwater Lake	Wright	Low algae	9.8 ft	6.3 µg/L	22 µg/L	3,187 acres
8	Clearwater Lake	Clearwater	Low algae	10 ft	3.2 µg/L	16 µg/L	999 acres
9	Lower Hay Lake	Crow Wing	Low algae	18.5 ft	2.7 µg/L	13 µg/L	700 acres
10	Latoka Lake	Douglas	Low algae	19 ft	2.2 µg/L	11 µg/L	767 acres
11	Little Birch Lake	Todd	Low algae	13 ft	3.1 µg/L	19 µg/L	839 acres
12	North Long Lake	Crow Wing	Low algae	15.1 ft	2.7 µg/L	14 µg/L	6,190 acres
13	Bad Medicine Lake	Becker	Low algae	25 ft	1.6 µg/L	6 µg/L	803 acres
14	Mud Lake	Becker	Low algae	12.5 ft	5.9 µg/L	22 µg/L	1,178 acres
15	Big Lake	Beltrami	Low algae	9.7 ft	4.8 µg/L	15 µg/L	3,598 acres
16	Big Lake	Carlton	Low algae	10 ft	3.2 µg/L	13.5 µg/L	526 acres
17	Big Lake	Sherburne	Low algae	13.6 ft	6.1 µg/L	10.5 µg/L	254 acres
18	Big Sugar Bush Lake	Becker	Low algae	16.5 ft	2.7 µg/L	10 µg/L	522 acres
19	Pelican Lake	Otter Tail	Low algae	16.4 ft	3 µg/L	15 µg/L	3,962 acres
20	Pelican Lake	Crow Wing	Low algae	14.3 ft	2.7 µg/L	11 µg/L	8,367 acres
21	Fullers Lake	Beltrami	Low algae	15 ft	2.4 µg/L	10 µg/L	-
22	Birch Lake	Ramsey	Low algae	5.9 ft	3.3 µg/L	21 µg/L	-
23	Birch Lake	Wright	Low algae	15 ft	4 µg/L	17 µg/L	100 acres
24	Birch Lake	Cass	Low algae	14 ft	4 µg/L	12 µg/L	1,267 acres
25	Round Lake	Aitkin	Low algae	14.5 ft	2.7 µg/L	10 µg/L	737 acres

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All-states list →Wisconsin version →Illinois version →Michigan version →Cleanest lakes in Minnesota →Swimming safety guide →Algae bloom guide →

Frequently Asked Questions

What is the best lake to swim in Minnesota?

Rainy Lake in Cass County ranks first for swimming in the 2026 Minnesota sampling record, combining the clearest water with low algae and public access. The full top 25 above is ranked the same way.

How do you know if a lake is safe to swim in Minnesota?

That is a call for MPCA and county health departments, who post seasonal and same-day advisories — always check before you swim, especially in late summer when blue-green algae bloom risk peaks. The readings on this page show what past sampling found: Secchi depth above 6 feet is a strong sign of low suspended sediment, and chlorophyll-a below 10 µg/L means a low algae load. Neither is a clearance.

Are lakes in Minnesota safe to swim in?

Whether a given lake is safe to swim in on a given day is answered by MPCA and the county health department, not by a water-quality reading. The lakes ranked above are filtered to the clearest, lowest-nutrient readings in the sampling record with chlorophyll-a below 10 µg/L, which means they have tested cleaner and carried less algae than the state average. Always check posted advisories before swimming and avoid water after heavy rain, when bacteria spikes from runoff.

What lakes have algae blooms in Minnesota?

Algae blooms (especially blue-green / cyanobacteria) are most common in shallow, warm, nutrient-rich (eutrophic) lakes during late summer. Lakes with high phosphorus and chlorophyll-a measurements are at higher risk. The lakes on this page are filtered to exclude high-algae lakes; each lake page shows its own phosphorus and chlorophyll-a readings.

When is it safe to swim in lakes in Minnesota?

Algae load in Minnesota lakes is typically lowest from late spring through early summer (May–July), when water is cool. It rises in late summer and early fall (August–September) when warm water and accumulated nutrients drive cyanobacteria blooms. Avoid swimming after heavy rainfall, when bacteria spikes from runoff, and check MPCA's current advisories the day you go.

What's the cleanest lake in Minnesota?

The single cleanest lake on measured clarity and nutrients leads the Minnesota cleanest-lakes ranking, linked below. The lakes on this page are filtered for swimming — the same clarity and nutrient readings, plus low chlorophyll-a (an active algae filter).

Our swimming filter

Lakes here have to pass three filters:

Clear, low-nutrient water — the top of the state’s measured range for clarity, phosphorus and chlorophyll-a
Chlorophyll-a below 10 µg/L — actively low algae density, low risk of harmful blue-green blooms
Multi-year sampling data — excludes lakes with limited sampling history (data confidence)

The Advisories & bacteria column adds a direct bacteria signal: where the EPA Water Quality Portal has enough E. coli or fecal-coliform samples, we show how often the lake has exceeded the EPA recreation threshold. It is a record of past testing, never a live "safe today" reading — bacteria spike fast after rain. Where a lake carries an EPA 303(d) bacteria or recreation listing, that advisory runs above the bacteria record in the table rather than beside it.

The ranking within the filter is by combined water-quality score (Secchi clarity + phosphorus + chlorophyll-a). Always check current MPCA advisories before swimming.

Where to swim near a Minnesota city

Looking for a lake close to home? These pages rank swimming lakes within driving distance of Minnesota's largest cities.

Swim near Minneapolis →Swim near St. Paul →Swim near Duluth →Swim near Rochester →Swim near Brainerd →Swim near St. Cloud →Swim near Mankato →Swim near Bemidji →Swim near Grand Rapids →Swim near Alexandria →Swim near Moorhead →Swim near Willmar →Swim near Park Rapids →Swim near Detroit Lakes →Swim near Ely →

Where to stay near Minnesota swimming lakes

Book a cabin, resort, or rental near Minnesota's cleanest swim lakes — live availability and prices for your beach weekend.

Top-rated places to stay near Minnesota swim lakes

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More on swimming water quality

Best Lakes for Swimming in America, Ranked (2026)

The cleanest lakes for swimming, ranked on EPA nutrient and algae data — plus the one thing a reading cannot tell you the day you go.

Is It Safe to Swim in a Lake? E. coli and Advisories

What a swim advisory actually means, how E. coli monitoring works, how fast a lake clears after rain, and why a long-term reading is not a swim guide.

Lake Water Temperature by Month: How Warm Lakes Get

Typical lake surface temperatures month by month and state by state, from years of monitoring readings — when lakes warm up, how warm they get, and when they turn.

Best Month to Swim, by State — Typical Lake Temperatures

The month when the cleanest lakes in each state are typically warmest, from long-run Water Quality Portal readings rather than this year’s weather.

Source: EPA National Aquatic Resource Surveys, 2026.