Cleanest Lake in Utah 2026: Top Rankings

The single cleanest lake in Utah is Flaming Gorge Reservoir (Daggett County, UT), ranked first on its measured clarity and nutrients in the 2026 sampling record. Cleanliness here is measured by Secchi depth (clarity), total phosphorus, and chlorophyll-a — all sourced from EPA Water Quality Portal and state agency sampling, shown as reported. The full top 25 ranked list appears below.

Ranking the cleanest Utah lakes means picking the basins with the lowest nutrient and algae readings, then the clearer water among lakes that tie. Flaming Gorge Reservoir (Daggett County, UT) leads the list, with Wide Hollow Reservoir close behind.

The top of the cleanest-lakes list is dominated by deep, glacial, cold-water basins — the same basins that carry the lowest nutrient readings overall. The pattern is not coincidence: depth and watershed land-use are the dominant inputs to water-clarity and nutrient-loading both.

Rank	Lake	County	Clarity	Phosphorus	Chlorophyll-a	Area
1	Flaming Gorge Reservoir (Daggett County, UT)	Daggett	31.8 ft	6.8 µg/L	1 µg/L	-
2	Wide Hollow Reservoir	Garfield	13.8 ft	36.5 µg/L	3.4 µg/L	-
3	Starvation Reservoir	Duchesne	11.2 ft	10 µg/L	1.4 µg/L	3,310 acres
4	Recapture Reservoir	San Juan	8.9 ft	15.1 µg/L	1.7 µg/L	-
5	Red Fleet Reservoir	Uintah	5.9 ft	20 µg/L	1.8 µg/L	521 acres
6	Newton Reservoir	Cache	15.4 ft	26 µg/L	1.7 µg/L	297 acres
7	Hyrum Reservoir	Cache	6.9 ft	17.9 µg/L	2.2 µg/L	480 acres
8	Moon Lake	Duchesne	9.5 ft	11.2 µg/L	2.7 µg/L	773 acres
9	Lake Powell Off Cha Canyon	San Juan	13.1 ft	9.4 µg/L	—	-
10	Lake Powell Goodhope Bay Midchannel	Garfield	6.1 ft	26 µg/L	—	-
11	Lake Powell Off Davis Gulch	Kane	15.4 ft	13.1 µg/L	—	-
12	Lake Powell Halls Xing	Kane	12.3 ft	15.9 µg/L	—	-
13	Jordanelle Reservoir	Wasatch	8.2 ft	20 µg/L	1.9 µg/L	-
14	Mona Reservoir	Juab	2 ft	53.5 µg/L	4.3 µg/L	-
15	Strawberry Reservoir Bryants Fk T	Wasatch	15.6 ft	20 µg/L	2 µg/L	-
16	Porcupine Reservoir	Cache	8.5 ft	13.3 µg/L	3.8 µg/L	-
17	Willard Bay Reservoir	Box Elder	2.3 ft	55 µg/L	7.9 µg/L	9,950 acres
18	Gsl Farmington Bay Outflow Lake	Davis	1 ft	484.5 µg/L	27.8 µg/L	-
19	Lower Bowns Reservoir	Garfield	9.2 ft	34 µg/L	9 µg/L	-
20	Cutler Reservoir	Cache	1.2 ft	109 µg/L	17.4 µg/L	5,460 acres
21	Mill Meadow Reservoir	Wayne	5.9 ft	66 µg/L	22.7 µg/L	-
22	Baker Dam Reservoir	Washington	3.6 ft	78 µg/L	29.5 µg/L	-
23	Matt Warner Reservoir E	Uintah	6.2 ft	72 µg/L	15.2 µg/L	-
24	Utah Lake Sp	Utah	0.7 ft	132 µg/L	55.3 µg/L	-
25	Farmington Bay Lake	Davis	—	405 µg/L	106 µg/L	-

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New nutrient and algae samples can move a lake up or down this ranking. Unsubscribe anytime.

All-states list →Clearest lakes in Utah (by Secchi clarity) →Minnesota version →Wisconsin version →Illinois version →Best swimming lakes in Utah →All Utah lakes →

Clearest lakes in Utah by water clarity

“Clearest” ranks by Secchi depth — how far you can see into the water — which can differ from the combined cleanliness score above. The clearest water in Utah is Flaming Gorge Reservoir at 31.8 ft of Secchi visibility.

1. Flaming Gorge Reservoir — 31.8 ft, Daggett County
2. Lake Mary — 26.9 ft, Salt Lake County
3. Flaming Gorge Reservoir Antelope Flat — 25.3 ft, Daggett County
4. Strawberry Marina Lake — 23.6 ft, Wasatch County
5. Strawberry Mid Res Lake — 22 ft, Wasatch County

See the full clearest-lakes ranking for Utah →

Frequently Asked Questions

What is the cleanest lake in Utah?

Flaming Gorge Reservoir (Daggett County, UT) ranks first on measured clarity and nutrients in the 2026 Utah sampling record. Each lake's nutrient and algae readings — total phosphorus, total nitrogen, chlorophyll-a, and turbidity — are shown beside the EPA National Lakes Assessment 2022 condition class for that lake's own ecoregion, so a reading is compared against the lakes it would naturally resemble. LakeQuality publishes no letter grade. Cleanliness here means a low nutrient load and little algae, measured directly from EPA and state DNR samples; where two lakes tie on nutrients and algae, the deeper Secchi reading ranks first.

Where in Utah has the cleanest water?

Utah's clearest waters are concentrated in deeper, lower-nutrient glacial basins with forested or low-agriculture watersheds. Among the current top-ranked lakes above, counties like Cache, Garfield, and Duchesne produce the highest-scoring lakes.

What is the clearest lake in Utah?

Flaming Gorge Reservoir is the clearest lake in Utah by water clarity, with a Secchi depth of 31.8 feet — the deepest transparency in our 2026 dataset. "Clearest" ranks by Secchi depth (how far you can see into the water) specifically, while "cleanest" combines clarity with phosphorus and chlorophyll-a. See our full clearest-lakes ranking for Utah for the top 25 by Secchi clarity.

Are these lakes safe to swim in?

Not on these readings alone. Clarity and nutrient readings are not a swimming clearance: they do not measure E. coli, cyanotoxins, or a posted beach closure, and a lake with low chlorophyll-a can still bloom. Always check current posted advisories before swimming: water quality changes seasonally, especially in late summer when blue-green algae bloom risk peaks.

How is this ranking calculated?

Lakes are ranked on phosphorus, chlorophyll-a and clarity as measured by EPA and state agency sampling, read against EPA National Lakes Assessment 2022 condition classes for that lake’s ecoregion, not a Utah-only 0–100 average. Water clarity is shown beside the nutrient readings. Lakes with limited sampling do not headline the table.

What are the top 5 cleanest lakes in the US?

There is no single national ranking of cleanest lakes — each state agency uses different metrics. Crater Lake (Oregon) is widely cited as the clearest US lake, with Secchi depths over 30 m. Lake Tahoe and Lake Superior are also top-tier nationally. Within Utah, the 25 lakes ranked above have the lowest nutrient and algae readings in our 2026 dataset.

How we rank cleanest lakes

Cleanliness here means three things working together:

Secchi clarity — how deep you can see into the water (in feet). Greater depth = clearer water = lower suspended sediment and algae.
Total phosphorus — the nutrient that fuels algae. Lower phosphorus levels mean less algae growth potential.
Chlorophyll-a — the green pigment in algae. Direct measurement of how much algae is currently in the water.

Each signal is normalized against Utah state norms and combined into a single 0–100 score. The lakes above are sorted by that combined score.Full methodology →

More on clean water

Lake Water Quality Explained: What the Readings Mean

How nutrient and algae readings are read against EPA ecoregion condition classes, what each class means in the water, and why a clean reading is not a clearance.

Cleanest Small Lakes in America 2026

The cleanest U.S. lakes under 500 acres, ranked on measured nutrients, algae, and water clarity — with the size cutoff applied to the lake, not the sample.

How to Choose a Clean Lake for a Cabin or Weekend Trip

A practical checklist for picking a lake with good water quality — clarity, phosphorus, algae history, depth, and the data to check before you commit.

Where to stay near Utah's cleanest lakes

Compare cabins, resorts, and rentals around Flaming Gorge Reservoir (Daggett County, UT) and the other lakes in this ranking, with live availability and prices for your trip. Each pin on the map is one of the ranked lakes above.

Top-rated places to stay near Flaming Gorge Reservoir (Daggett County, UT)

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Source: EPA National Aquatic Resource Surveys, 2026.