Muskoka District County Lake Quality

Ontario, 170 lakes, average grade B (Good)

Muskoka District County in Ontario carries 170 graded lakes — one of the lake-richer counties in our dataset. Coverage that dense usually reflects active lake-association sampling alongside state-agency monitoring. With an average grade of B, Muskoka District County sits comfortably above the Ontario median.

Most of the county's monitored lakes are shallow — under 50 feet — which means wind keeps the water column mixed all summer and sediment-bound phosphorus releases back into the surface layer whenever the bottom is disturbed. Bella Lake (A) is the cleanest in the county.

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Quick Answers for Muskoka District County

Cleanest lakes in Muskoka District County →Cleanest lakes in Ontario →Safest swimming lakes in Ontario →

Planning a trip? Check special fishing regulations for Bella Lake — or check the official Ontario fishing regulations.

All Lakes in Muskoka District County

Rank	Lake	Grade	Clarity	Phosphorus
1	Bella Lake	A	16.4 ft	7.6 µg/L
2	Bonnie Lake	A	19.7 ft	5 µg/L
3	Buck Lake	A	20.7 ft	8.3 µg/L
4	Camp Lake	A	23 ft	5.8 µg/L
5	Clear Lake	A	21.3 ft	5 µg/L
6	Clearwater Lake	A	18 ft	6 µg/L
7	Deer Lake	A	21.3 ft	5.9 µg/L
8	Deer Lake	A	27.9 ft	-
9	Fifteen Mile Lake	A	18 ft	6.8 µg/L
10	Grandview Lake	A	23 ft	-
11	Harp Lake	A	15.7 ft	6.6 µg/L
12	Joseph Lake	A	21.3 ft	3.3 µg/L
13	Lake of Bays	A	18 ft	6 µg/L
14	Margaret Lake	A	21.8 ft	3 µg/L
15	Rosseau Lake	A	16.4 ft	10.3 µg/L
16	Shoe Lake	A	14.9 ft	5 µg/L
17	Six Mile Lake	A	16.1 ft	-
18	Skeleton Lake	A	29.7 ft	3.9 µg/L
19	Spring Lake	A	19.7 ft	5.4 µg/L
20	Sunny Lake	A	15.3 ft	-
21	Tackaberry Lake	A	17.7 ft	4.6 µg/L
22	Tucker Lake	A	22.6 ft	6.2 µg/L
23	Walker Lake	A	16.4 ft	6.8 µg/L
24	Wolfkin Lake	A	17.1 ft	6.5 µg/L
25	Arrowhead Lake	A	-	11.7 µg/L
26	Barnes Lake	A	-	7.7 µg/L
27	Cronk Lake	A	-	11.4 µg/L
28	Echo Lake	A	-	7.5 µg/L
29	Highland Pond	A	-	9.3 µg/L
30	Hillman Lake	A	-	8.5 µg/L
31	Marion Lake	A	-	13.8 µg/L
32	Mossy Lake	A	-	10.4 µg/L
33	North Healey Lake	A	-	4.9 µg/L
34	South Tasso Lake	A	-	6 µg/L
35	Thorne Lake	A	-	12.7 µg/L
36	Atkins Lake	A	-	9.2 µg/L
37	Bastedo Lake	A	-	8.2 µg/L
38	Bing Lake	A	-	4.4 µg/L
39	Camel Lake	A	-	9.3 µg/L
40	Clearwater Lake	A	-	14.5 µg/L
41	Devine Lake	A	-	15.4 µg/L
42	Flatrock Lake	A	-	8.6 µg/L
43	Galla Lake	A	-	6.7 µg/L
44	Grindstone Lake	A	-	9.1 µg/L
45	Gullwing Lake	A	-	12.7 µg/L
46	Halfway Lake	A	-	12.2 µg/L
47	Heney Lake	A	-	6.5 µg/L
48	Mainhood Lake	A	-	7.3 µg/L
49	Robinson Lake	A	-	20 µg/L
50	Rose Lake	A	-	14.4 µg/L
51	Siding Lake	A	-	11.9 µg/L
52	Thinn Lake	A	-	9.1 µg/L
53	Tooke Lake	A	-	3.8 µg/L
54	Wildcat Lake	A	-	10.7 µg/L
55	Bass Lake	A	11.5 ft	13.4 µg/L
56	Baxter Lake	A	11.2 ft	9.8 µg/L
57	Bigwind Lake	A	14.8 ft	5.4 µg/L
58	Brooks Lake	A	11.5 ft	6.6 µg/L
59	Chub Lake	A	11 ft	6.3 µg/L
60	Cognashene Lake	A	11.5 ft	7.7 µg/L
61	Cooper Lake	A	11.8 ft	8.9 µg/L
62	Cornall Lake	A	11.2 ft	19.6 µg/L
63	Echo Lake	A	10.8 ft	7.5 µg/L
64	Ennis Lake	A	10.2 ft	7.9 µg/L
65	Frau Lake	A	10.8 ft	12.9 µg/L
66	Go Home Lake	A	13.8 ft	6.3 µg/L
67	Gull Lake	A	12.1 ft	8 µg/L
68	Henshaw Lake	A	14.4 ft	5.7 µg/L
69	Hesners Lake	A	13.1 ft	6.7 µg/L
70	High Lake	A	13.8 ft	4.6 µg/L
71	Leech Lake	A	12.3 ft	7.3 µg/L
72	Leonard Lake	A	11.5 ft	6.3 µg/L
73	Little Long Lake	A	12.8 ft	9.3 µg/L
74	Long Lake	A	14.8 ft	7.3 µg/L
75	Long Turtle Lake	A	11.5 ft	9.7 µg/L
76	Loon Lake	A	10.5 ft	12 µg/L
77	Mccrae Lake	A	10.2 ft	9.1 µg/L
78	Medora Lake	A	11.2 ft	8 µg/L
79	Muskoka Lake	A	11.5 ft	7.2 µg/L
80	Nutt Lake	A	11.8 ft	10.4 µg/L
81	Otter Lake	A	12.8 ft	6.2 µg/L
82	Oxbow Lake	A	13.1 ft	5.7 µg/L
83	Palette Lake	A	11.8 ft	10.6 µg/L
84	Peninsula Lake	A	14.8 ft	10.3 µg/L
85	Pigeon Lake	A	14.4 ft	9.1 µg/L
86	Pine Lake	A	12.5 ft	7.9 µg/L
87	Pine Lake	A	11.2 ft	7.1 µg/L
88	Rebecca Lake	A	12.1 ft	7 µg/L
89	Ripple Lake	A	11.8 ft	10.7 µg/L
90	Silver Lake	A	10.2 ft	10.3 µg/L
91	South Muldrew Lake	A	10.5 ft	7.4 µg/L
92	South Nelson Lake	A	11.2 ft	8 µg/L
93	St Mary Lake	A	11.5 ft	7.8 µg/L
94	Tasso Lake	A	10.8 ft	4.6 µg/L
95	Torrance Lake	A	13.1 ft	4.7 µg/L
96	Turtle Lake	A	10.8 ft	7.7 µg/L
97	Waseosa Lake	A	12.1 ft	6.6 µg/L
98	Wood Lake	A	11.8 ft	7.4 µg/L
99	Ada Lake	B	6.9 ft	17.6 µg/L
100	Bird Lake	B	9.8 ft	10.1 µg/L
101	Bruce Lake	B	9.8 ft	11.1 µg/L
102	Butterfly Lake	B	9.2 ft	14.3 µg/L
103	Cherry Island Lake	B	13.5 ft	-
104	Dickie Lake	B	8.2 ft	6.2 µg/L
105	Dotty Lake	B	10.2 ft	-
106	Fairy Lake	B	8.5 ft	8.1 µg/L
107	Gibson Lake	B	7.2 ft	12.9 µg/L
108	Jevins Lake	B	6.9 ft	10.5 µg/L
109	Kahshe Lake	B	9.2 ft	13.1 µg/L
110	Longline Lake	B	9.8 ft	17.6 µg/L
111	Mansell Lake	B	7.2 ft	10.5 µg/L
112	Mary Lake	B	9.4 ft	7.4 µg/L
113	Mckay Lake	B	9.2 ft	9.3 µg/L
114	Mirror Lake	B	9 ft	5.7 µg/L
115	Moon River Lake	B	9.8 ft	6.5 µg/L
116	Morrison Lake	B	8.5 ft	6.8 µg/L
117	Myers Lake	B	11.5 ft	-
118	North Muldrew Lake	B	9.8 ft	8.9 µg/L
119	Oudaze Lake	B	6.9 ft	10 µg/L
120	Penfold Lake	B	9.2 ft	16.4 µg/L
121	Porcupine Lake	B	9.8 ft	7.8 µg/L
122	Prospect Lake	B	9.8 ft	7.7 µg/L
123	Ril Lake	B	9.5 ft	7.5 µg/L
124	Spence Lake	B	8.9 ft	9.5 µg/L
125	Stewart Lake	B	9.8 ft	6.2 µg/L
126	Tadenac Lake	B	9.8 ft	7.9 µg/L
127	Toad Lake	B	8.9 ft	6.5 µg/L
128	Vernon Lake	B	7.9 ft	7.9 µg/L
129	Young Lake	B	8.5 ft	10.9 µg/L
130	Fawn Lake	B	-	21.1 µg/L
131	Nelson Lake	B	9.8 ft	12.2 µg/L
132	Ben Lake	B	4.9 ft	8.6 µg/L
133	Cardwell Lake	B	4.9 ft	9.9 µg/L
134	Chub Lake	B	6.6 ft	10.4 µg/L
135	Dark Lake	B	4.9 ft	14.1 µg/L
136	Fox Lake	B	6.6 ft	9.1 µg/L
137	Gilleach Lake	B	4.9 ft	10.6 µg/L
138	Golden City Lake	B	6.6 ft	12.8 µg/L
139	Gullfeather Lake	B	6.6 ft	12.4 µg/L
140	Haggart Lake	B	4.9 ft	9.7 µg/L
141	Healey Lake	B	6.2 ft	9.4 µg/L
142	Longs Lake	B	5.6 ft	8 µg/L
143	Mcdonald Lake	B	6.6 ft	11.4 µg/L
144	Mcrey Lake	B	6.6 ft	14.7 µg/L
145	Moot Lake	B	6.6 ft	14.6 µg/L
146	Neilson Lake	B	4.9 ft	19.4 µg/L
147	Nine Mile Lake	B	6.2 ft	7.6 µg/L
148	Pells Lake	B	6.6 ft	11.8 µg/L
149	Ricketts Lake	B	6.6 ft	9.6 µg/L
150	Riley Lake	B	6.6 ft	14.4 µg/L
151	Ryde Lake	B	4.9 ft	19.1 µg/L
152	Silver Sand Lake	B	5.2 ft	9.4 µg/L
153	Stoneleigh Lake	B	3.9 ft	15.5 µg/L
154	Three Mile Lake	B	6.6 ft	15.3 µg/L
155	Toronto Lake	B	6.6 ft	7.8 µg/L
156	Webster Lake	B	4.3 ft	13.3 µg/L
157	Weismuller Lake	B	6.6 ft	11.6 µg/L
158	Bass Lake	C	5.9 ft	26.6 µg/L
159	Brandy Lake	C	3.6 ft	24.9 µg/L
160	Clark Lake	C	3.3 ft	13.1 µg/L
161	Doe Lake	C	5.6 ft	25.3 µg/L
162	Jessop Lake	C	3.3 ft	9.1 µg/L
163	Menominee Lake	C	7.9 ft	-
164	Onawa Lake	C	2.3 ft	19.7 µg/L
165	Roundabout Lake	C	7.7 ft	-
166	Three Mile Lake	C	5.2 ft	21.8 µg/L
167	Barron Lake	C	2.6 ft	28.4 µg/L
168	Bearpaw Lake	D	4.9 ft	-
169	Black Lake	D	4.1 ft	-
170	Garter Snake Lake	D	5.9 ft	-

Other Counties in Ontario

Southwestern Ontario County

1 lake · Avg grade A

Dufferin County

1 lake · Avg grade A

Unorganized Division No. 1 County

1 lake · Avg grade A

Renfrew County

83 lakes · Avg grade A

Lanark County

29 lakes · Avg grade A

Hastings County

66 lakes · Avg grade A

See how Muskoka District County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 38 states.

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Source: EPA National Aquatic Resource Surveys, 2026.