Grade C Lakes, Fair

1,114 lakes (20% of all graded lakes)

C is the largest bracket on the rubric for many states: productive, swimmable most days, with the occasional July week where blooms make the water unappealing. 1,114 lakes grade C.

Eutrophic conditions dominate, with the bracket reflecting the algal pressure that comes from elevated phosphorus and the right summer temperatures. About 9% of the C-grade bracket is deep lakes, with the remainder shallow. Depth helps but does not guarantee a grade — watershed land use does most of the heavy lifting.

A B C D F

1,114

Total Lakes

States Covered

MN 482WI 300MI 132MO 71ND 57NY 30IA 18IL 16IN 5OH 3

Lake	County	State	Clarity	Depth	Fish
Horseshoe Lake	Chisago	MN	4.6 ft	53 ft	14
Bass Lake	Washington	MN	6.5 ft	-	0
Schram Lake	Beltrami	MN	3.9 ft	-	0
Green Lake	Chisago	MN	6 ft	32 ft	15
Crystal Lake	Dakota	MN	7 ft	37 ft	13
Duck Lake	Hennepin	MN	5.9 ft	-	0
Wild Rice Lake	Carlton	MN	3.2 ft	-	0
Lost Lake	Washington	MN	6.3 ft	34 ft	11
O'Dowd Lake	Scott	MN	5.5 ft	22 ft	10
Simian Lake	St. Louis	MN	3.9 ft	-	0
Spruce Lake	Carlton	MN	2.3 ft	-	0
Hardwood Lake	Carlton	MN	5.1 ft	-	0
Rice Portage Lake	Carlton	MN	1.3 ft	-	0
Turtle Lake Deep	Cook	MN	-324.8 ft	-	0
Middle Pigeon Lake	Itasca	MN	7.5 ft	-	0
Westwood Lake	Hennepin	MN	5.6 ft	-	0
Ml-Seventeen Lake	Aitkin	MN	6.2 ft	42 ft	21
Teal Lake Deep	Cook	MN	3.3 ft	-	0
Hornbean Lake	Dakota	MN	7.2 ft	-	0
Cut Foot Sioux Lake	Itasca	MN	8.5 ft	-	0
Jellums Lake	Washington	MN	6 ft	-	0
Gaslyn Lake	Burnett	WI	4.5 ft	12 ft	3
Chippewa Flowage -Pokegema Lake	Sawyer	WI	5.8 ft	92 ft	8
Quarry Lake	Brown	WI	8 ft	-	0
Back Bay Lake	Chippewa	MI	4.9 ft	-	0
Irondequoit Bay Lake	Monroe	NY	7 ft	-	0
Pomme de Terre L. Lake	Hickory	MO	4.8 ft	-	0
Table Rock L. Nr. Greens Hollow Lake	Barry	MO	5 ft	-	0
Table Rock L. Nr. S. Kanakuk-Kanakom Beach Lake	Stone	MO	5.2 ft	-	0
Lost Valley Lake	Gasconade	MO	3.9 ft	-	0
Little Prairie Lake by Dam	Phelps	MO	4.9 ft	-	0
Port Hudson Lake	Franklin	MO	6.1 ft	-	0
Bowling Green Lake	Pike	MO	5.5 ft	-	0
Stockton Lake-L.Sac Arm	Dade	MO	4.3 ft	-	0
Aspen Lake Along Southern Arm	Warren	MO	3.8 ft	-	0
Clearwater Lake	Reynolds	MO	2.3 ft	-	0
Waukomis Lake	Platte	MO	4.7 ft	-	0
Hazel Creek Lk. Lake	Adair	MO	3.6 ft	-	0
Little Prairie Lake	Phelps	MO	8.6 ft	-	0
Lake Tishomingo Nr. Dam	Jefferson	MO	5.4 ft	-	0
Loto Lake	Morgan	MO	5.3 ft	-	0
Loto Lake	Morgan	MO	5.6 ft	-	0
Loto Lake	Camden	MO	7 ft	-	0
Loto Lake	Morgan	MO	4.9 ft	-	0
Peaceful Valley Lake	Gasconade	MO	4 ft	-	0
Loto Lake	Camden	MO	7.7 ft	-	0
Loto Lake	Morgan	MO	4.5 ft	-	0
Namakan Lake	St. Louis	MN	8.2 ft	150 ft	18
Rainy Lake	St. Louis	MN	9.5 ft	161 ft	17
Sand Point Lake	St. Louis	MN	7.5 ft	184 ft	21
Oslo Lake	St. Louis	MN	9.2 ft	36 ft	2
Namakan Lake	St. Louis	MN	9.8 ft	150 ft	18
Jorgens Lake	St. Louis	MN	7.2 ft	21 ft	3
Rainy Lake	St. Louis	MN	7.2 ft	161 ft	17
War Club Lake	St. Louis	MN	7.9 ft	40 ft	8
Round Lake	Hennepin	MN	6.6 ft	37 ft	8
Round Lake	Ramsey	MN	8 ft	-	0
Round Lake	Itasca	MN	7.5 ft	16 ft	0
Horseshoe Lake	Cook	MN	7.7 ft	26 ft	0
Horseshoe Lake	Lake	MN	8 ft	40 ft	0
Stark Lake	Crow Wing	MN	8 ft	66 ft	10
Long Lake	Itasca	MN	7.5 ft	34 ft	14
Long Lake	Meeker	MN	7.5 ft	28 ft	12
Big Swan Lake	Todd	MN	9 ft	45 ft	16
Medicine Lake	Hennepin	MN	7.9 ft	49 ft	15
Twin Lake	Ramsey	MN	7.5 ft	33 ft	8
Bryant Lake	Hennepin	MN	9.8 ft	45 ft	11
Clear Lake	Otter Tail	MN	7 ft	29 ft	13
One Pine Lake	St. Louis	MN	4.5 ft	13 ft	13
Fish Lake	Dakota	MN	7.2 ft	33.5 ft	7
Battle Creek Lake	Washington	MN	7.2 ft	15.3 ft	10
Shell Lake	St. Louis	MN	9 ft	15 ft	8
Florence Lake	Isanti	MN	8.9 ft	26 ft	15
Birch Lake	Ramsey	MN	5.9 ft	-	0
Birch Lake	Sherburne	MN	5.8 ft	18 ft	13
Birch Lake	St. Louis	MN	3.9 ft	25 ft	10
Gibson Lake	Lake	MN	7 ft	24 ft	0
Leech Lake	Cass	MN	9 ft	-	0
Bass Lake	Pine	MN	8.3 ft	24 ft	9
Bass Lake	Otter Tail	MN	8.5 ft	36 ft	7
Crooked Lake	Lake	MN	9 ft	165 ft	0
Crooked Lake	Lake	MN	3 ft	4 ft	0
Mille Lacs Lake	Mille Lacs	MN	9 ft	42 ft	21
Cedar Lake	Aitkin	MN	8.8 ft	18 ft	9
Carp Lake	Unknown	MN	8.5 ft	34 ft	10
Pelican Lake	St. Louis	MN	7.5 ft	38 ft	11
Fairy Lake	St. Louis	MN	7 ft	19 ft	0
Clearwater Lake	Itasca	MN	9.5 ft	16 ft	0
Mud Lake	Wright	MN	5.6 ft	65 ft	15
Unnamed Lake	Dakota	MN	6 ft	-	3
Unnamed Lake	Crow Wing	MN	6.6 ft	-	0
Unnamed Lake	Morrison	MN	6.9 ft	-	0
Unnamed Lake	Itasca	MN	7.9 ft	-	0
Unnamed Lake	St. Louis	MN	4.8 ft	7 ft	6
Unnamed Lake	Grant	MN	6.7 ft	-	0
Unnamed Lake	Otter Tail	MN	3.9 ft	-	0
Maple Lake	Wright	MN	9 ft	-	0
Stella Lake	Meeker	MN	7.5 ft	75 ft	15
Wind Lake	Lake	MN	9 ft	32 ft	10
Blue Lake	Isanti	MN	8.9 ft	31 ft	13

Showing 100 of 1,114 Grade C lakes.

Frequently Asked Questions

How many lakes have a grade of C?

There are 1,114 Grade C (Fair) lakes across the 12 states LakeQuality covers, led by Minnesota (482) and Wisconsin (300). This represents 20% of all graded lakes.

What does a Grade C mean?

Grade C means fair water quality with moderate clarity (7-10 ft visibility), moderate phosphorus, and some algae presence. Generally safe for swimming but algae blooms possible in summer.

Featured Grade C Lakes

Horseshoe Lake

Chisago County, MN · 4.6 ft clarity

Bass Lake

Washington County, MN · 6.5 ft clarity

Schram Lake

Beltrami County, MN · 3.9 ft clarity

Green Lake

Chisago County, MN · 6 ft clarity

Crystal Lake

Dakota County, MN · 7 ft clarity

Duck Lake

Hennepin County, MN · 5.9 ft clarity

Source: EPA National Aquatic Resource Surveys, 2026.