Published March 9, 2026 · Updated August 18, 2026
Best Lakes for Swimming in America, Ranked (2026)
Out of 13,297 monitored lakes across the 49 states and 2 Canadian provinces, 6,377 currently grade A or B for nutrients and algae. These 15 sit at the top of that list. A high grade is a reason to put a lake on the trip list. It is not permission to skip the water in front of you.
The 15 highest-graded lakes
The current leader is Sunset Lake in Rutland County, VT, at about 36.1 feet of Secchi clarity and chlorophyll-a around 1.3 µg/L. Clarity is shown because it is what a swimmer sees. The letter itself is scored on phosphorus, nitrogen, chlorophyll-a, and turbidity against EPA ecoregion reference lakes — see what A–F actually means.
| Rank | Lake | State | County | Grade | Clarity (ft) | Area |
|---|---|---|---|---|---|---|
| 1 | Sunset Lake | VT | Rutland | A | 36.1 | - |
| 2 | Flaming Gorge Reservoir | UT | Daggett | A | 31.8 | - |
| 3 | Caspian Lake | VT | Orleans | A | 29.5 | 789 acres |
| 4 | Clearwater Lake | MN | Cook | A | 29 | 462 acres |
| 5 | Shadow Lake | VT | Orleans | A | 28.9 | 199 acres |
| 6 | Maidstone Lake | VT | Essex | A | 28.5 | 800 acres |
| 7 | Lake Willoughby | VT | Orleans | A | 28.2 | - |
| 8 | Holland Lake | MN | Dakota | A | 27.9 | 38 acres |
| 9 | Kerbs Lake | MN | Otter Tail | A | 27.7 | - |
| 10 | Little Mcdonald Lake | MN | Otter Tail | A | 26.5 | 1,316 acres |
| 11 | Lake Elligo | VT | Orleans | A | 26.2 | - |
| 12 | Forest Lake | VT | Washington | A | 25.6 | - |
| 13 | Bad Medicine Lake | MN | Becker | A | 25 | 803 acres |
| 14 | Serpent Lake | MN | Crow Wing | A | 25 | 1,116 acres |
| 15 | Big Cormorant Lake | MN | Becker | A | 24.8 | 3,657 acres |
For the always-current table, open the best swimming lakes hub and the cleanest-lakes ranking. A seasonal cut of the same list is in Summer 2026: The Cleanest Lakes to Swim Right Now.
What a high grade is good for — and what it is not
A- and B-graded lakes tend to share a few physical facts: deeper basins that stratify in summer, watersheds that are more forest than feedlot, and chlorophyll-a low enough that the water does not look like soup. Those are useful for picking a cabin weekend. They are silent about the two things that actually close a beach: fecal bacteria after a storm, and a cyanobacteria bloom on a hot still week.
The CDC harmful algal bloom pages and the EPA CyanoHABs program are the day-of authorities. Dogs are especially vulnerable to cyanotoxins; if the water looks wrong, they stay on the sand. The practical checklist is in Is It Safe to Swim? and the swimming safety guide.
One more caveat, because the ATTAINS overlap is large enough to matter: 53.0% of A-graded lakes in the matched set still appear on a state 303(d) list. The listing is usually mercury in fish, PFAS, or pathogens — none of which enter the letter. An A is compatible with a fish-consumption advisory. Read both.
How to use this list on a real trip
- Start here or on the swimming hub to shortlist lakes, not to declare a beach open.
- Open the lake page for the grade, the impairment panel, and the current algae context.
- Check the state health department beach program the morning you go — Minnesota's beach monitoring page is one example; every health department in coverage runs a counterpart.
- Stay out of green scum, and keep pets out too. That rule outranks any letter on this site.
Frequently Asked Questions
Among 9,479 graded lakes across the 49 states and 2 Canadian provinces, the current leader is Sunset Lake in VT. The 15 lakes in the table hold the highest combined nutrient-and-algae scores on record. The continuously updated versions are at lakequality.org/ranking/cleanest and lakequality.org/best/swimming.
No. An A is a long-term nutrient and algae statement, not a beach clearance. It is blind to E. coli and to cyanotoxins on a given afternoon. Cross-checked against EPA ATTAINS, 53.0% of A-graded lakes still carry a Clean Water Act impairment listing. Check current beach and algae advisories before you get in.
It is the same ranking as the cleanest-lakes table: EPA Water Quality Portal samples scored against National Lakes Assessment ecoregion condition classes for phosphorus, nitrogen, chlorophyll-a, and turbidity. Secchi clarity is shown because it is what you see from the beach; it is not the grade.
Look at the water. Stay out of anything that looks like spilled paint, pea soup, or a green surface scum. Skip swimming for a day or two after heavy rain. Check your state health department’s current beach and harmful-algal-bloom advisories — and keep dogs out of scummy water.
No. D and F mean higher nutrients and algae in that ecoregion — Nutrient-rich and Algae-prone — not a skip-the-trip rating. Check local advisories before swimming, and skip the water if you see scum. Cabins and rentals around those lakes are still listed on each lake page.
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