Oligotrophic

Oligotrophic Lakes Across 38 States

Low nutrients, clear water, excellent for swimming. 100 lakes (21% of all graded lakes).

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 the 49 states and 2 Canadian provinces LakeQuality covers, 100 lakes register as oligotrophic — 62% 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.

Oligotrophic Mesotrophic Eutrophic Hypereutrophic

Lake	County	State	Grade	Clarity	Depth
Rainy Lake	Cass	MN	A	13.9 ft	29 ft
East Fox Lake	Crow Wing	MN	A	16.4 ft	65 ft
Deep Portage Lake	Cass	MN	A	15.4 ft	105 ft
Clearwater Lake	Cook	MN	A	29 ft	65 ft
Lower Hay Lake	Crow Wing	MN	A	18.5 ft	100 ft
Latoka Lake	Douglas	MN	A	19 ft	108 ft
Bad Medicine Lake	Becker	MN	A	25 ft	84 ft
Big Sugar Bush Lake	Becker	MN	A	16.5 ft	42 ft
Pelican Lake	Crow Wing	MN	A	14.3 ft	104 ft
Fullers Lake: East Basin	Beltrami	MN	A	15 ft	-
Birch Lake	Cook	MN	A	18 ft	69 ft
Round Lake	Aitkin	MN	A	14.5 ft	125 ft
Round Lake	Cook	MN	A	16.5 ft	45 ft
Round Lake	Beltrami	MN	A	18 ft	38 ft
Ada Lake	Cass	MN	A	14 ft	60 ft
Pike Lake	Cook	MN	A	17.4 ft	45 ft
Long Lake	Clearwater	MN	A	20.5 ft	80 ft
Long Lake	Cass	MN	A	21.5 ft	115 ft
Long Lake	Beltrami	MN	A	20 ft	87 ft
Long Lake	Becker	MN	A	19.5 ft	61 ft
Long Lake	Beltrami	MN	A	14 ft	-
Long Lake	Itasca	MN	A	16.7 ft	72 ft
Long Lake	Itasca	MN	A	16.9 ft	85 ft
Dead Lake	Hubbard	MN	A	16 ft	34 ft
Maple Lake	Cass	MN	A	13.3 ft	45 ft
Maple Lake	Itasca	MN	A	15.3 ft	39 ft
West Twin Lake	Crow Wing	MN	A	13.3 ft	42 ft
Shallow Lake	Itasca	MN	A	16.4 ft	85 ft
Trout Lake	Itasca	MN	A	18 ft	157 ft
Trout Lake	Cook	MN	A	18.4 ft	77 ft
Deer Lake	Itasca	MN	A	13.1 ft	121 ft
Cowdry Lake	Douglas	MN	A	17.1 ft	52 ft
Ossawinnamakee Lake	Crow Wing	MN	A	20 ft	63 ft
Clear Lake	Crow Wing	MN	A	18 ft	63 ft
Clear Lake	Itasca	MN	A	14.9 ft	30 ft
Spectacle Lake	Isanti	MN	A	13.8 ft	51.5 ft
Bear Lake	Lake	MN	A	17.4 ft	31 ft
Blue Lake	Hubbard	MN	A	17.3 ft	84 ft
Eagle Lake	Otter Tail	MN	A	22.6 ft	46 ft
West Fox Lake	Crow Wing	MN	A	15 ft	55 ft
Star Lake	Crow Wing	MN	A	19 ft	83 ft
Fish Lake	Otter Tail	MN	A	18 ft	69 ft
Benedict Lake	Hubbard	MN	A	11.5 ft	91 ft
Square Lake	Washington	MN	A	17 ft	68 ft
Shell Lake	Beltrami	MN	A	13 ft	-
Woman Lake	Cass	MN	A	15 ft	-
Green Lake	Beltrami	MN	A	18.5 ft	-
Girl Lake	Cass	MN	A	17.6 ft	81 ft
Mow Lake	Hubbard	MN	A	14.5 ft	34 ft
Charlotte Lake	Wright	MN	A	17.1 ft	46 ft
Big Mcdonald Lake	Otter Tail	MN	A	17.4 ft	46 ft
Bass Lake	Otter Tail	MN	A	17.4 ft	-
Bass Lake	Crow Wing	MN	A	16.1 ft	47 ft
Bass Lake	Itasca	MN	A	18.2 ft	65 ft
Island Lake	St. Louis	MN	A	14.5 ft	65 ft
Island Lake	Crow Wing	MN	A	15.1 ft	76 ft
Island Lake	Cass	MN	A	17.5 ft	40 ft
Island Lake	Beltrami	MN	A	16 ft	-
Island Lake	Hubbard	MN	A	16.4 ft	32 ft
Moose Lake	Beltrami	MN	A	15.1 ft	71 ft
Crooked Lake	Hubbard	MN	A	19 ft	-
Crooked Lake	Crow Wing	MN	A	15 ft	54 ft
Cedar Lake	Morrison	MN	A	16.2 ft	88 ft
Big Pine Lake	Aitkin	MN	A	17 ft	78 ft
Lizzie Lake	Otter Tail	MN	A	16.4 ft	66 ft
Turtle Lake	Becker	MN	A	23 ft	73 ft
Turtle Lake	Itasca	MN	A	17.1 ft	54 ft
Lower Bottle Lake	Hubbard	MN	A	15 ft	110 ft
Pokegama Lake	Itasca	MN	A	16.1 ft	112 ft
Sandy Lake	Beltrami	MN	A	16 ft	-
Pickerel Lake	Becker	MN	A	18 ft	74 ft
Strawberry Lake	Becker	MN	A	17.5 ft	40 ft
Gull Lake	Cook	MN	A	15.5 ft	-
Henderson Lake	Kandiyohi	MN	A	13.5 ft	57 ft
Upper Birch Lake	Isanti	MN	A	10.8 ft	-
Upper Bottle Lake	Hubbard	MN	A	16 ft	55 ft
Courthouse Lake	Carver	MN	A	18.9 ft	57 ft
Silver Lake	St. Louis	MN	A	19.3 ft	29 ft
Heart Lake	Beltrami	MN	A	14.5 ft	-
West Battle Lake	Otter Tail	MN	A	18 ft	108 ft
Wabana Lake	Itasca	MN	A	18 ft	115 ft
Roy Lake	Crow Wing	MN	A	11.7 ft	26 ft
Little Mantrap Lake	Hubbard	MN	A	17 ft	54 ft
Clitherall Lake	Otter Tail	MN	A	14.1 ft	69 ft
Kimball Lake	Crow Wing	MN	A	18.4 ft	77 ft
Baby Lake	Cass	MN	A	12.5 ft	69 ft
Crystal Lake	Cass	MN	A	16 ft	40 ft
West Sylvia Lake	Wright	MN	A	22 ft	97 ft
Serpent Lake	Crow Wing	MN	A	25 ft	65 ft
North Twin Lake	Beltrami	MN	A	17.4 ft	59 ft
Stuart Lake	Otter Tail	MN	A	17.5 ft	49 ft
North Star Lake	Itasca	MN	A	19 ft	90 ft
Pleasant Lake	Cass	MN	A	15.5 ft	72 ft
Little Bass Lake	Beltrami	MN	A	16 ft	22 ft
Pulaski Lake	Wright	MN	A	18 ft	-
Little Mcdonald Lake	Otter Tail	MN	A	26.5 ft	109 ft
Bay Lake	Crow Wing	MN	A	18.5 ft	74 ft
Webb Lake	Cass	MN	A	18 ft	84 ft
Little Hubert Lake	Crow Wing	MN	A	18 ft	41 ft
Big Trout Lake	Crow Wing	MN	A	16.9 ft	128 ft

Frequently Asked Questions

What is an oligotrophic lake?

Low nutrients, clear water, excellent for swimming. There are 100 oligotrophic lakes across the 49 states and 2 Canadian provinces LakeQuality covers, representing 21% of all graded lakes.