Shallow Lakes in Minnesota & Wisconsin

Q: Are shallow lakes safe for swimming?

Many shallow lakes are safe for swimming, especially those with Grade A or B water quality. However, shallow lakes are more prone to algae blooms in late summer due to warmer water temperatures and wind-mixed nutrients. Always check for blue-green algae advisories before swimming.

Q: Why do shallow lakes have more algae?

Shallow lakes warm up faster and wind mixes nutrients from the bottom into the water column, fueling algae growth. Without a thermocline to trap nutrients in deep water, the entire lake becomes a growth zone for algae. This is why shallow lakes are more likely to receive lower water quality grades.

Lakes under 20 feet deep in Minnesota and Wisconsin ranked by water quality. Shallow lakes warm quickly in summer and are great for wading and family swimming, but are more susceptible to algae blooms and winter fish kills.

Maximum-depth data currently comes from the Minnesota and Wisconsin DNR lake surveys, so these rankings cover MN and WI lakes only. Grades for the other 10 covered states are based on clarity and nutrient measurements.

Deep (50+ ft)Medium (20-50 ft)Shallow (<20 ft)

100

Total Lakes

Minnesota

Wisconsin

Rank	Lake	County	State	Grade	Depth	Area	Fish
1	Cabin Lake	Lake	MN	A	3 ft	66 acres	3
2	Cramer Lake	Lake	MN	A	4 ft	68 acres	5
3	South Twin Lake	Polk	WI	A	9 ft	72 acres	3
4	Smith Lake	Marinette	WI	A	11 ft	20 acres	0
5	Crystal Bog Lake	Vilas	WI	A	8 ft	1 acres	0
6	Park Creek Pond	Douglas	WI	A	7 ft	9 acres	2
7	Sanborn Lake	Vilas	WI	A	13 ft	243 acres	3
8	Tambling Lake	Vilas	WI	A	11 ft	172 acres	4
9	Arnegard Dam Lake	McKenzie	ND	A	12.2 ft	24 acres	5
10	Olson Lake	Washington	MN	A	15 ft	87 acres	11
11	Lost Lake	Sawyer	WI	A	13 ft	51 acres	2
12	Signalness Lake	Pope	MN	A	14 ft	42 acres	9
13	Little Whitefish Lake	Itasca	MN	A	15 ft	160 acres	0
14	Dunnigan Lake	Lake	MN	A	14 ft	81 acres	5
15	Cable Lake	Polk	MN	A	14 ft	194 acres	0
16	Hennepin Lake	Hubbard	MN	A	14 ft	418 acres	0
17	Outlet of Onamia Lake on the Rum River	Mille Lacs	MN	A	10 ft	1,044 acres	0
18	Outlet of Ogechie Lake on the Rum River	Mille Lacs	MN	A	6 ft	409 acres	0
19	Bass Lake	Barron	WI	A	14 ft	118 acres	3
20	Bass Lake	Vilas	WI	A	15 ft	272 acres	5
21	Boulder Lake	Oconto	WI	A	11 ft	370 acres	5
22	Mud Lake	Sawyer	WI	A	15 ft	464 acres	4
23	Maple Lake	Oneida	WI	A	15 ft	131 acres	5
24	Snipe Lake	Vilas	WI	A	15 ft	216 acres	4
25	Sams Lake	Shawano	WI	A	13 ft	6 acres	2
26	Mcclaine Lake	Sawyer	WI	A	15 ft	53 acres	5
27	Horseshoe Lake	Cass	MN	B	12 ft	127 acres	0
28	Shallow Lake	Hubbard	MN	B	10 ft	284 acres	13
29	Mill Lake	Becker	MN	B	10 ft	155 acres	14
30	Fourteen Lake	St. Louis	MN	B	14.5 ft	386 acres	7
31	Everett Lake	St. Louis	MN	B	15 ft	113 acres	8
32	Pine Lake	Clearwater	MN	B	15 ft	1,236 acres	12
33	Pine Lake	St. Louis	MN	B	14 ft	450 acres	8
34	Three Island Lake	Cass	MN	B	13 ft	288 acres	8
35	Tait Lake	Cook	MN	B	15 ft	355 acres	6
36	Battle Lake	Itasca	MN	B	15 ft	243 acres	11
37	Ryan Lake	St. Louis	MN	B	13 ft	34 acres	4
38	Laddie Lake	Anoka	MN	B	4 ft	66 acres	0
39	Clara Lake	Cook	MN	B	15 ft	388 acres	6
40	School Section Lake	Stearns	MN	B	14 ft	211 acres	8
41	Dick Lake	Cook	MN	B	12 ft	127 acres	5
42	North Branch Kawishi Lake	Lake	MN	B	13 ft	182 acres	7
43	Town Line Lake	Cass	MN	B	11 ft	698 acres	8
44	Crow River Mill Pond	Kandiyohi	MN	B	14 ft	2,290 acres	13
45	Sargent Lake	Mahnomen	MN	B	15 ft	138 acres	12
46	Big Rice Lake	St. Louis	MN	B	5 ft	1,917 acres	0
47	Dragon Lake	Lake	MN	B	15 ft	79 acres	10
48	Campers Lake	Lake	MN	B	2.5 ft	48 acres	5
49	Pickerel Lake	Oconto	WI	B	10 ft	176 acres	3
50	Pickerel Lake	Lincoln	WI	B	14 ft	49 acres	3
51	Crooked Lake	Burnett	WI	B	13 ft	250 acres	3
52	Cranberry Lake	Bayfield	WI	B	12 ft	131 acres	5
53	Rice Lake	Forest	WI	B	6 ft	201 acres	3
54	Lulu Lake	Shawano	WI	B	13 ft	37 acres	3
55	Walsh Lake	Forest	WI	B	15 ft	45 acres	1
56	Benson Lake	Vilas	WI	B	15 ft	28 acres	7
57	Fay Lake	Florence	WI	B	10 ft	272 acres	4
58	Half Moon Lake	Bayfield	WI	B	10 ft	106 acres	3
59	Hatch Lake	Waupaca	WI	B	12 ft	113 acres	3
60	Jungle Lake	Forest	WI	B	14 ft	180 acres	4
61	Kangaroo Lake	Door	WI	B	12 ft	1,156 acres	5
62	Birch Island Lake	Burnett	WI	B	13 ft	768 acres	3
63	Youngs Lake Waupaca Co	Waupaca	WI	B	15 ft	3 acres	5
64	Glisezinski Lake	Portage	WI	B	11 ft	35 acres	3
65	Horn Lake	Oconto	WI	B	11 ft	131 acres	4
66	Upper Kimball Lake	Washburn	WI	B	11 ft	42 acres	3
67	Halfmoon Lake	Lincoln	WI	B	14 ft	102 acres	3
68	Lower Phantom Lake	Waukesha	WI	B	12 ft	373 acres	3
69	Big Twin Lake	Waushara	WI	B	13 ft	93 acres	3
70	Unnamed Lake	Oneida	WI	B	12 ft	2 acres	0
71	Unnamed Lake	Douglas	WI	B	6 ft	20 acres	0
72	Dads Lake	Vilas	WI	B	15 ft	52 acres	3
73	Unnamed Bog Lake	Vilas	WI	B	15 ft	8 acres	0
74	Morgan Lake	Florence	WI	B	10 ft	44 acres	1
75	Fawn Lake-Deep Hole	Burnett	WI	B	14 ft	29 acres	3
76	Wintergreen Lake	Price	WI	B	15 ft	50 acres	3
77	King Lake	Polk	WI	B	14 ft	53 acres	3
78	Springville Pond	Portage	WI	B	10 ft	14 acres	3
79	Siskiwit Lake	Bayfield	WI	B	13 ft	285 acres	5
80	Little Rice Lake	Forest	WI	B	10 ft	1,201 acres	3
81	Inlet To Dunes Lake	Door	WI	B	1 ft	48 acres	0
82	Siskiwit Lake	Bayfield	WI	B	13 ft	285 acres	5
83	Indian School Lake	Sawyer	WI	B	6 ft	65 acres	3
84	Buck Lake	Burnett	WI	B	6 ft	66 acres	3
85	Little Pigeon Lake	Manitowoc	WI	B	14.5 ft	8 acres	3
86	Davis Dam Lake	Slope	ND	B	5.8 ft	15 acres	1
87	Spider Lake	Chisago	MN	B	9 ft	131 acres	7
88	Rogers Lake	Dakota	MN	B	8 ft	102 acres	7
89	Indian Lake	Sawyer	WI	B	9 ft	76 acres	3
90	Blackhawk Lake	Dakota	MN	B	12 ft	40 acres	7
91	Arrowhead Lake	Crow Wing	MN	B	13 ft	296 acres	16
92	Peary Lake	St. Louis	MN	B	15 ft	116 acres	8
93	Norway Lake	Cass	MN	B	12 ft	515 acres	14
94	Moose Lake	Itasca	MN	B	11 ft	48 acres	0
95	Rice Lake	Cook	MN	B	10 ft	223 acres	6
96	Calhoun Lake	Kandiyohi	MN	B	13 ft	647 acres	15
97	Elbow Lake	Cook	MN	B	9 ft	408 acres	7
98	Upper Twin Lake	Hubbard	MN	B	12 ft	213 acres	18
99	Little Sand Lake	Cass	MN	B	12 ft	413 acres	10
100	Crow R Mill Pond	Kandiyohi	MN	B	14 ft	2,290 acres	13

Frequently Asked Questions

Are shallow lakes safe for swimming?

Many shallow lakes are safe for swimming, especially those with Grade A or B water quality. However, shallow lakes are more prone to algae blooms in late summer due to warmer water temperatures and wind-mixed nutrients. Always check for blue-green algae advisories before swimming.

Why do shallow lakes have more algae?

Shallow lakes warm up faster and wind mixes nutrients from the bottom into the water column, fueling algae growth. Without a thermocline to trap nutrients in deep water, the entire lake becomes a growth zone for algae. This is why shallow lakes are more likely to receive lower water quality grades.

Notable Shallow Lakes

Cabin Lake

Lake County, MN · Grade A · 3 ft

Cramer Lake

Lake County, MN · Grade A · 4 ft

South Twin Lake

Polk County, WI · Grade A · 9 ft

Smith Lake

Marinette County, WI · Grade A · 11 ft

Crystal Bog Lake

Vilas County, WI · Grade A · 8 ft

Park Creek Pond

Douglas County, WI · Grade A · 7 ft

Source: EPA National Aquatic Resource Surveys, 2026.