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LakeQuality
B

Thunder Bay District County Lake Quality

Ontario, 300 lakes, average grade B (Good)

Thunder Bay District County has 300 graded lakes, enough that within-county variation matters as much as the county average. Some are deep glacial basins, others are shallow agricultural-watershed waters, and the grade distribution reflects that mix. The county-wide average lands at B — solid water quality with most lakes carrying clear summer transparency and low-to-moderate phosphorus.

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. Arrow Lake (A) is the cleanest in the county.

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All Lakes in Thunder Bay District County

RankLakeGradeClarityPhosphorus
1Arrow LakeA24 ft7.5 µg/L
2Athelstane LakeA-12.1 µg/L
3Batwing LakeA-13.8 µg/L
4Burchell LakeA-7.5 µg/L
5Deception LakeA20.2 ft5.8 µg/L
6Hawkeye LakeA-12.8 µg/L
7Hazelwood LakeA-8.3 µg/L
8Hoof LakeA-15.9 µg/L
9Little Athelstane LakeA-11.9 µg/L
10Loon LakeA-8.9 µg/L
11Myrt LakeA-6.4 µg/L
12Oliver LakeA19 ft5.2 µg/L
13Pagwachuan LakeA17.4 ft-
14Prelate LakeA-14.5 µg/L
15Silver LakeA16.1 ft5.1 µg/L
16Sunday LakeA-13.4 µg/L
17Sunset LakeA15.6 ft7.9 µg/L
18Two Island LakeA-11.1 µg/L
19Obonga LakeA-7.5 µg/L
20Deer LakeA-8.2 µg/L
21Elizabeth LakeA-9.7 µg/L
22Firehill LakeA-8.5 µg/L
23Florence LakeA-6.1 µg/L
24Foxxe LakeA-4.4 µg/L
25Frazer LakeA-6.8 µg/L
26Hicks LakeA-8.9 µg/L
27Jackfish LakeA-10.1 µg/L
28Little Santoy LakeA-7.1 µg/L
29Lofquist LakeA-6.2 µg/L
30Maki LakeA-9.1 µg/L
31Mary LakeA-11.3 µg/L
32Mcleish LakeA-8.4 µg/L
33Milton LakeA-16.6 µg/L
34Paul LakeA-9 µg/L
35Polly LakeA-11.6 µg/L
36Rolland LakeA-7.6 µg/L
37Sandstone LakeA-7.9 µg/L
38Santoy LakeA-5.1 µg/L
39Stewart LakeA-6.5 µg/L
40Timmus LakeA-4.8 µg/L
41Walkinshaw LakeA-10.5 µg/L
42Whitelily LakeA-11.9 µg/L
43Whitesand LakeA15.1 ft5.6 µg/L
44Windigokan LakeA-8 µg/L
45Yellowhammer LakeA-6.1 µg/L
46Arnott LakeA23 ft14.3 µg/L
47Bamoos LakeA16.4 ft12.3 µg/L
48Burchell L. LakeA20.7 ft3.2 µg/L
49Castle L. LakeA16.7 ft6.3 µg/L
50Cry L. LakeA24.3 ft4.2 µg/L
51Empire LakeA20.8 ft12.2 µg/L
52Greenwater LakeA47.9 ft1.8 µg/L
53Greenwater L. LakeA15.4 ft6.1 µg/L
54Grouse L. LakeA15.1 ft6.3 µg/L
55Little Moraine LakeA22.6 ft9.6 µg/L
56Magone LakeA26.2 ft12.7 µg/L
57Minchin LakeA15.7 ft6.2 µg/L
58Mishi LakeA18 ft3.9 µg/L
59Pagwachuan LakeA15.4 ft6.8 µg/L
60Pringle LakeA17.6 ft5.1 µg/L
61Squeers LakeA19.7 ft11.4 µg/L
62Sturgeon LakeA21 ft-
63Unknown LakeA19.7 ft5.8 µg/L
64Walotka L. LakeA16.4 ft5.4 µg/L
65Waweig L. LakeA19 ft5.9 µg/L
66Wig LakeA14.9 ft9 µg/L
67Bass LakeA11.8 ft8.3 µg/L
68Greenwater LakeA12.6 ft13 µg/L
69Icarus LakeA11.8 ft9.2 µg/L
70Island LakeA12.6 ft8.2 µg/L
71Shebandowan LakeA10.8 ft9.3 µg/L
72Superior LakeA10.8 ft5.2 µg/L
73White LakeA11.2 ft8.2 µg/L
74Windigoostigwan LakeA11.5 ft5.6 µg/L
75Arrow L. LakeA12.8 ft6.1 µg/L
76Athelstane L. LakeA10.5 ft8.5 µg/L
77Atik L. LakeA12.1 ft8.3 µg/L
78Barbara LakeA10.8 ft3.5 µg/L
79Beatty L. LakeA13.5 ft9.7 µg/L
80Bisect LakeA11.5 ft6.4 µg/L
81Camel Read LakeA13.1 ft4.8 µg/L
82Cliff LakeA14.8 ft5.5 µg/L
83Crevasse LakeA13.8 ft6.9 µg/L
84De Lesseps LakeA11.5 ft4.5 µg/L
85Disraeli LakeA13.1 ft7.4 µg/L
86Eileen LakeA14.8 ft11.1 µg/L
87Fallingsnow L. LakeA12.8 ft5.3 µg/L
88Fernow LakeA13.1 ft9.1 µg/L
89Frazer L. LakeA10.5 ft7.4 µg/L
90Hilma LakeA10.5 ft11.2 µg/L
91Huronian L. LakeA10.5 ft5.3 µg/L
92Innes L. LakeA10 ft7.4 µg/L
93Jackfish LakeA13.1 ft9.3 µg/L
94Jeno LakeA12.1 ft18.6 µg/L
95Kagiano LakeA11.5 ft6.2 µg/L
96Kamikau L. LakeA10.8 ft5.1 µg/L
97Killala LakeA13.3 ft7.4 µg/L
98Klotz LakeA10.3 ft11 µg/L
99Lake NipigonA11.5 ft9.2 µg/L
100Little North LakeA19.7 ft25.6 µg/L
101Long LakeA10.2 ft7 µg/L
102Mack LakeA11.2 ft16.2 µg/L
103Mckay LakeA11.5 ft9.9 µg/L
104North Mccrea LakeA11.5 ft5.7 µg/L
105Parks LakeA10.3 ft6.7 µg/L
106Saganagons LakeA10 ft8.6 µg/L
107Sandspit LakeA12.3 ft10.7 µg/L
108Sandstone L. LakeA10.2 ft8.4 µg/L
109Shacabac LakeA13.1 ft19 µg/L
110Springwater LakeA13.5 ft10.9 µg/L
111Stetham L. LakeA10.2 ft5.9 µg/L
112Tilly L. LakeA11.2 ft3.9 µg/L
113Tinto L. LakeA10.5 ft6.7 µg/L
114Titmarsh L. LakeA12.1 ft5.2 µg/L
115Twinhouse L. LakeA11.8 ft6.3 µg/L
116Wawang LakeA11.2 ft10.6 µg/L
117Weewullee L. LakeA10.5 ft7.7 µg/L
118Wideman L. LakeA12.8 ft6.5 µg/L
119Wildgoose LakeA11.6 ft7.7 µg/L
120Wintering LakeA12.3 ft8 µg/L
121Barnum LakeB7.2 ft9.2 µg/L
122Burk LakeB9.8 ft6 µg/L
123Elbow LakeB9.5 ft8.3 µg/L
124Iron Range LakeB8.9 ft7.7 µg/L
125Kashabowie LakeB7.4 ft6.9 µg/L
126Loon LakeB7.5 ft12.5 µg/L
127Lyne LakeB9.8 ft7.1 µg/L
128Marks LakeB6.9 ft10.4 µg/L
129Peterkin LakeB7.5 ft12.2 µg/L
130Roundtable LakeB7.9 ft8.8 µg/L
131Shebandowan LakeB8 ft12 µg/L
132Shebandowan LakeB9.2 ft7.9 µg/L
133Spike LakeB7.4 ft10.5 µg/L
134Sunbow LakeB7.5 ft8.9 µg/L
135Swallow LakeB-23.4 µg/L
136Tomlinson LakeB7.5 ft9.1 µg/L
137Tornroos LakeB9.2 ft9.3 µg/L
138Upper Hunter'S LakeB9.5 ft6.8 µg/L
139Walker LakeB9 ft5.4 µg/L
140Warnica LakeB9.5 ft12.9 µg/L
141Whitefish LakeB8 ft10.7 µg/L
142Beck LakeB6.9 ft11.1 µg/L
143Bedivere LakeB7.7 ft13.6 µg/L
144Bell LakeB12.8 ft-
145Black Sturgeon L. LakeB9.8 ft4.4 µg/L
146Buckaday LakeB9.4 ft10.1 µg/L
147Burrows LakeB6.9 ft11.4 µg/L
148Cairngorm LakeB8.7 ft5.1 µg/L
149Charon LakeB8.2 ft15.6 µg/L
150Circle L. LakeB6.9 ft10.5 µg/L
151Clegge LakeB8.9 ft5.6 µg/L
152Diablo LakeB9.8 ft11.4 µg/L
153Dilla LakeB8.5 ft9.9 µg/L
154Dog L. LakeB7.5 ft7.9 µg/L
155Elbow L. LakeB8.2 ft10 µg/L
156Ellen LakeB8.5 ft4 µg/L
157Gamsby LakeB8.2 ft6.8 µg/L
158Gennis LakeB8.5 ft8.1 µg/L
159Granite LakeB8.2 ft7.6 µg/L
160Greenbush LakeB9.7 ft7.3 µg/L
161Greenwich L. LakeB7.5 ft4.2 µg/L
162Hamilton LakeB9.2 ft6.4 µg/L
163Harmon LakeB7.2 ft8.3 µg/L
164Hine LakeB6.9 ft8.6 µg/L
165Icarus L. LakeB6.9 ft10.4 µg/L
166Kashabowie L. LakeB8.9 ft7.8 µg/L
167Kashishibog LakeB8.2 ft8.3 µg/L
168Kawaweogama LakeB9.4 ft9.2 µg/L
169Kearns L. LakeB6.9 ft10.9 µg/L
170Kilbarry LakeB8.2 ft7.9 µg/L
171Kilgour LakeB7.2 ft8.2 µg/L
172Kwinkwaga LakeB7.9 ft6.6 µg/L
173Little Hilma LakeB7.2 ft6 µg/L
174Louise LakeB8.2 ft7 µg/L
175Lower Shebandowan LakeB7.2 ft10.5 µg/L
176Macintosh LakeB7.2 ft7.5 µg/L
177Marie Louise LakeB8.2 ft8.6 µg/L
178Mccrea LakeB9.2 ft7.4 µg/L
179Middle Shebandowan LakeB9 ft7.4 µg/L
180Middle Shebandowan LakeB7.5 ft10 µg/L
181Mikinak LakeB7.2 ft10 µg/L
182Mowe L. LakeB8.2 ft10.7 µg/L
183Nalla LakeB13 ft20.2 µg/L
184Northern Light L. LakeB8.5 ft11.4 µg/L
185Obonga L. LakeB9.2 ft5.3 µg/L
186Onaman LakeB7.4 ft10.4 µg/L
187One Island LakeB7.4 ft4.2 µg/L
188Oskawe LakeB8.2 ft9.5 µg/L
189Pakashkan L. LakeB9.8 ft9.9 µg/L
190Partridge LakeB8.2 ft6.5 µg/L
191Proctor LakeB9.8 ft8.3 µg/L
192Randolph LakeB9.8 ft7.1 µg/L
193Ripple LakeB7.9 ft7.9 µg/L
194Rudge L. LakeB9.8 ft5.1 µg/L
195Savant LakeB13.8 ft-
196Scruffy LakeB7.2 ft10 µg/L
197Shawanibis LakeB7.2 ft6.1 µg/L
198Silver LakeB7.5 ft8.2 µg/L
199South Beatty LakeB8.2 ft9.7 µg/L
200Stingray LakeB9.8 ft5.3 µg/L
201Upper Shebandowan LakeB9.2 ft7.2 µg/L
202Victoria LakeB13.5 ft-
203Weese LakeB8.2 ft7.5 µg/L
204White Otter LakeB8.7 ft9.1 µg/L
205Cummins LakeB5.2 ft11.3 µg/L
206Fodder LakeB3.6 ft13.1 µg/L
207Greenpike LakeB6.4 ft8.3 µg/L
208Ham LakeB6.2 ft11.3 µg/L
209Howcum LakeB5.7 ft12.6 µg/L
210Lenore LakeB6.6 ft12.3 µg/L
211Little Cedar LakeB6.2 ft16.4 µg/L
212Lottit LakeB4.9 ft11.8 µg/L
213Maccormack LakeB6.2 ft9.2 µg/L
214Madalaine LakeB6.6 ft9.8 µg/L
215One Island LakeB6.1 ft8 µg/L
216Reta LakeB6.1 ft7.4 µg/L
217Shaco LakeB6.4 ft8 µg/L
218Surprise LakeB5.6 ft10.8 µg/L
219Trout LakeB5.9 ft10.5 µg/L
220Wartman LakeB4.9 ft9 µg/L
221Addie LakeB6.2 ft11.7 µg/L
222Arrowroot LakeB4.9 ft8.2 µg/L
223Barbara LakeB6.2 ft12.5 µg/L
224Batwing L. LakeB5.6 ft8.8 µg/L
225Big Duck LakeB4.9 ft12.1 µg/L
226Bigamy LakeB3.4 ft10.1 µg/L
227Blunder LakeB5.1 ft12.3 µg/L
228Brightsand LakeB4.9 ft10.8 µg/L
229Catlonite LakeB6.2 ft7.1 µg/L
230Cavell LakeB4.9 ft6.6 µg/L
231Crayfish LakeB5.9 ft8.6 µg/L
232Frank LakeB5.2 ft12.5 µg/L
233Grassy LakeB6.6 ft9.8 µg/L
234Greenwood LakeB6.6 ft9 µg/L
235Heathcote LakeB4.9 ft6.4 µg/L
236Holinshead L. LakeB5.9 ft15.9 µg/L
237Holly L. LakeB6.6 ft7.3 µg/L
238Jacob LakeB6.2 ft19.9 µg/L
239Jolly L. LakeB5.2 ft13.5 µg/L
240Kekekuab LakeB4.9 ft14.6 µg/L
241Lac des Iles LakeB6.6 ft18.4 µg/L
242Des Mille Lacs LakeB5.9 ft17.7 µg/L
243Lac du Milieu LakeB5.9 ft16.2 µg/L
244Marks LakeB3.9 ft16.6 µg/L
245Little Metionga LakeB5.2 ft12.7 µg/L
246Loganberry LakeB4.9 ft15.1 µg/L
247Lost L. LakeB5.6 ft9.1 µg/L
248Mackenzie LakeB6.6 ft13.7 µg/L
249Maggotte L. LakeB5.2 ft8.7 µg/L
250Mccrea LakeB6.2 ft7 µg/L
251Metionga LakeB5.6 ft10.2 µg/L
252Muskeg LakeB5.6 ft19.4 µg/L
253Muskrat L. LakeB5.9 ft18.7 µg/L
254Nelson LakeB6.6 ft12.4 µg/L
255Pearson LakeB6.2 ft16.2 µg/L
256Penassen LakeB6.6 ft8.2 µg/L
257Pinel LakeB5.6 ft8.9 µg/L
258Purdom L. LakeB5.2 ft10.9 µg/L
259Rabbitbelly LakeB5.2 ft12.2 µg/L
260Redhead LakeB4.3 ft9.3 µg/L
261Ricestalk LakeB4.3 ft14.4 µg/L
262Sandison LakeB4.3 ft7.3 µg/L
263Sassenach LakeB5.6 ft6.2 µg/L
264Savas LakeB4.6 ft13.3 µg/L
265Shabuskwia LakeB4.9 ft9.7 µg/L
266Sparkling L. LakeB6.6 ft8.7 µg/L
267Sprat LakeB3.9 ft9.5 µg/L
268Union LakeB6.6 ft13.6 µg/L
269Upper Hunters LakeB6.6 ft8.6 µg/L
270Upper Kaogomok LakeB4.9 ft15.9 µg/L
271Wabakimi LakeB6.6 ft6.6 µg/L
272Wabinosh LakeB5.6 ft15.5 µg/L
273Wapikaimaski LakeB5.7 ft8.2 µg/L
274Weaver LakeB5.9 ft12.1 µg/L
275Webster LakeB5.9 ft8.3 µg/L
276Weikwabinonaw LakeB5.2 ft10.1 µg/L
277West Arm Armistice LakeB4.9 ft10.5 µg/L
278Whiteclay LakeB6.6 ft7 µg/L
279Young LakeB3.6 ft17.3 µg/L
280Beaverkit LakeC2.6 ft11.4 µg/L
281Cloud LakeC4.3 ft23.9 µg/L
282Cushing LakeC3.8 ft21.1 µg/L
283Lac des Mille Lacs LakeC4.3 ft22.7 µg/L
284No Name LakeC9.2 ft-
285Upsala LakeC7.9 ft-
286Arc LakeC7.5 ft-
287Bukemiga LakeC6.6 ft23.3 µg/L
288Kenogamisis LakeC3.3 ft15.1 µg/L
289Seseganaga LakeC7.5 ft-
290Snowshoe LakeC6.6 ft22.1 µg/L
291Cox LakeD2 ft51.3 µg/L
292Wabikoba LakeD6.6 ft-
293Bertaud LakeD6.2 ft-
294Fitchie LakeD5.2 ft-
295Fog LakeD5.9 ft-
296Frain LakeD4.9 ft-
297Miniss L. LakeD6.2 ft-
298Pashkokogan LakeD6.2 ft-
299Selwyn LakeD4.3 ft-
300Smye LakeD4.9 ft-

See how Thunder Bay 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.