Cleanest Small Lakes in America 2026

Driving the news

Winner among 1,078 complete U.S. grades with known area under 500 acres: Clearwater Lake (MN), 462 acres.
lake.com’s 2025 “cleanest small lakes” winner, Lake Louise in Isleworth, Florida, is in our file as Louise Lake — Grade B, phosphorus 8 µg/L. It is not an A, and acreage is unpublished here, so it cannot top a size ranking.
Axhandle Lake in Chippewa County, Wisconsin — listed near the top of that same 276-lake chemistry report — grades B here, with phosphorus 14 µg/L on 86 acres. That is not the 0.170 mg/L (170 µg/L) phosphorus figure the chemistry list attached to the name.

A small-lake ranking has to start with size

lake.com’s “Cleanest Small Lakes in the US” report is easy to misread as an acreage ranking. Its methodology, as published, selected 276 lakes with samples taken in water five meters deep or shallower between January 1, 2023 and May 28, 2024, required the word “lake” in the name, and scored eight chemicals. Depth of the sample is not surface area of the lake. A large, shallow reservoir can enter that set; a 40-acre kettle lake with no recent shallow-station chemistry cannot.

This page answers the acreage question the title implies. A lake qualifies only if we know its surface area, that area is under 500 acres, the U.S. nutrient-and-algae grade is complete (not limited-data), and the name is clean enough to put in a ranked table. 1,078 lakes currently clear that bar across the 39 states and 2 Canadian provinces we grade. Missing acreage is missing — those lakes still have pages; they just cannot win a size contest.

The 10 cleanest small lakes, named

In order: Clearwater Lake (MN, 462 acres), Holland Lake (MN, 38 acres), Turtle Lake (MN, 196 acres), Six Lake (MN, 197 acres), Swenson Lake (MN, 412 acres), Mayhew Lake (MN, 221 acres), Long Lake (MN, 159 acres), Gilmore Lake (MN, 93 acres), Little Sand Lake (MN, 410 acres), and Long Lake (MN, 412 acres).

The 15 cleanest U.S. lakes under 500 acres

Rank is the complete nutrient-and-algae grade, then Secchi depth, then lower phosphorus. Area is published acres. These are not swimming clearances.

Rank	Lake	State	Grade	Acres	Clarity (ft)	Phosphorus (µg/L)
1	Clearwater Lake	MN	A	462	29	4
2	Holland Lake	MN	A	38	27.9	14
3	Turtle Lake	MN	A	196	23	8
4	Six Lake	MN	A	197	21	7
5	Swenson Lake	MN	A	412	20.7	8
6	Mayhew Lake	MN	A	221	20.6	5
7	Long Lake	MN	A	159	20.5	7
8	Gilmore Lake	MN	A	93	20.3	10
9	Little Sand Lake	MN	A	410	20	7
10	Long Lake	MN	A	412	20	7
11	Scalp Lake	MN	A	254	20	9
12	Long Lake	MN	A	415	19.5	8
13	Lone Lake	MN	A	69	19.4	7
14	East Silent Lake	MN	A	324	19.2	10
15	Ponto Lake	MN	A	388	19	8

What the 276-lake chemistry list actually measured

Two names from that report are in our file, and they are the right test of whether “cleanest small” meant clean, or meant a shallow-sample chemical index.

Louise Lake in Orange County, Florida, is the Butler Chain waterbody behind the Isleworth headline. It grades B on EPA ecoregion classes, with 9.2 feet of Secchi and 8 µg/L phosphorus. A B is a solid recreational grade for subtropical Florida. It is not the national A-grade small-lake champion, and without published acres it cannot enter the table above.

Axhandle Lake in Chippewa County, Wisconsin, does have a size: 86 acres. It grades B, 10.2 feet of Secchi, phosphorus 14 µg/L. A chemistry list that put it near the top with phosphorus of 0.170 mg/L was ranking a different measurement, or a different sample, than the ecoregion grade on this site.

The same report named Utah Lake the dirtiest in that 276-lake set. On our scale Utah Lake grades F, with chlorophyll-a around 157 µg/L and phosphorus around 530 µg/L — among the worst complete U.S. grades, and not a small lake. That part of the chemistry story and our nutrient grade agree on direction, not on sample size.

How to use a small-lake list

Small oligotrophic lakes are often clearer than famous reservoirs because they sit in forested catchments with less phosphorus, not because they were sampled in five meters of water. Use this table for cabin and paddling shortlists. Pair it with the national cleanest-and-dirtiest report (no size filter), the Secchi ranking, and current algae advisories. A 40-acre A-grade lake can still close a beach after a calm, hot week.

14,370 monitored lakes sit behind these 15 rows. Most never appear in a 46-lake or 276-lake chemistry roundup. That is the point of grading the full set.

Frequently Asked Questions

A lake with a published surface area under 500 acres, a complete (not limited-data) U.S. nutrient-and-algae grade, and a name clean enough for a ranking table. Lakes with unknown acreage are excluded — missing size is not treated as small.

That report scored 276 lakes whose samples were taken in water five meters deep or less, required the word “lake” in the name, and ranked on eight chemicals. It was not an acreage ranking. Our list is an acreage ranking: known area under 500 acres, complete EPA ecoregion grades, Secchi as the tie-breaker.

Lake Louise (Orange County, Florida — the Butler Chain / Isleworth waterbody in our file as Louise Lake) grades B in our data, with 9.2 feet of Secchi and 8 µg/L phosphorus. It is not an A, and it has no published acreage in this dataset, so it cannot win a size-filtered ranking.

No. The letter is nutrients and algae against an ecoregion class over a typical summer. It is not E. coli, not a same-day HAB clearance, and not a depth-safety rating. Check posted beach and algae advisories the day you go.