What are oligotrophic lakes in Utah?

25 oligotrophic lakes in Utah. Low nutrients, clear water, excellent for swimming.

What does oligotrophic mean?

Low nutrients, clear water, excellent for swimming.

Oligotrophic Lakes in Utah

An oligotrophic lake is what most people picture when they think of pristine northern lake country: clarity to depth, no algal scum, cold water that holds dissolved oxygen all the way to the bottom even in August. Across Utah, 25 lakes register as oligotrophic — 0% of them break 50 feet of depth, which is the structural condition that underwrites the trophic class. Without depth and a low-nutrient watershed, oligotrophy is hard to sustain.

On our A–F scale, oligotrophic lakes almost always pull an A or B — the same low-nutrient conditions that produce the trophic class also produce the high grade.

#	Lake	County	Grade	Clarity	Depth	TSI
1	Flaming Gorge Reservoir Antelope Flat	Daggett	A	25.3 ft	-	31
2	Flaming Gorge Reservoir	Daggett	A	31.8 ft	-	30
3	Starvation Reservoir	Duchesne	A	11.2 ft	-	38
4	Recapture Reservoir	San Juan	A	8.9 ft	-	42
5	Little Dell Reservoir	Salt Lake	A	14.8 ft	-	36
6	Red Fleet Reservoir	Uintah	A	5.9 ft	-	45
7	Silver Lake Flat Reservoir	Utah	A	10.5 ft	-	37
8	Settlement Canyon Reservoir	Tooele	A	8.5 ft	-	39
9	Lake Mary	Salt Lake	A	26.9 ft	-	26
10	Millsite Reservoir	Emery	A	10.5 ft	-	43
11	Newton Reservoir	Cache	A	15.4 ft	-	42
12	Mantua Reservoir N	Box Elder	A	3 ft	-	46
13	Third Dam Lake	Cache	A	4.3 ft	-	42
14	Quail Creek Reservoir	Washington	A	14.6 ft	-	33
15	Ferron Reservoir	Sanpete	A	19 ft	-	34
16	Posey Lake	Garfield	A	16.4 ft	-	39
17	Palisade Lake	Sanpete	A	5.1 ft	-	44
18	Tropic Reservoir	Garfield	A	12.3 ft	-	34
19	Lake Powell Off Cha Canyon	San Juan	B	13.1 ft	-	38
20	Lake Powell Off Davis Gulch	Kane	B	15.4 ft	-	39
21	Lyman Lake	Summit	B	19.7 ft	-	37
22	Causey Reservoir	Weber	B	15.1 ft	-	36
23	Jordanelle Reservoir	Wasatch	C	8.2 ft	-	44
24	Strawberry Reservoir Bryants Fk T	Wasatch	C	15.6 ft	-	41
25	Strawberry Reservoir Narrows T	Wasatch	C	17.1 ft	-	42

All oligotrophic lakes →Minnesota version →Wisconsin version →Illinois version →Michigan version →Iowa version →Ohio version →Pennsylvania version →New York version →Missouri version →Indiana version →North Dakota version →South Dakota version →Florida version →Colorado version →North Carolina version →Vermont version →Texas version →Oregon version →Arkansas version →Oklahoma version →Kansas version →Nebraska version →Nevada version →Arizona version →Idaho version →Montana version →New Mexico version →Tennessee version →Alabama version →Virginia version →Kentucky version →Washington version →Wyoming version →Georgia version →Massachusetts version →Ontario version →Québec version →Nova Scotia version →British Columbia version →Newfoundland and Labrador version →All Utah lakes →

Source: EPA National Aquatic Resource Surveys, 2026.