Washtenaw County Lake Quality

Wisconsin, 17 lakes, average grade C (Fair)

Washtenaw County's 17 graded lakes fall in the moderate-density bracket for Michigan. The county-level average smooths over real differences — a single agricultural watershed near the southwest corner can pull the average down even if the rest of the county runs clean. The county average is C — the middle of the rubric, with one or two lakes pulling the average up or down depending on year.

The county's lakes lean shallow, which makes the grades sensitive to wind, sediment-resuspension, and any nutrient inputs from the watershed. The cleanest lake on the books is Silver Lake (A); the most-stressed is First Sister Lake (F).

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Quick Answers for Washtenaw County

Cleanest lakes in Washtenaw County →Cleanest lakes in Wisconsin →Safest swimming lakes in Wisconsin →

Planning a trip? Check special fishing regulations for Silver Lake, whether the fish are safe to eat, and the best times to fish — or browse the full Wisconsin regulations index.

All Lakes in Washtenaw County

Rank	Lake	Grade	Clarity	Max Depth	Phosphorus
1	Silver Lake	A	11.5 ft	-	-
2	North Lake North Central Basin; Dexter Township	A	12 ft	-	-
3	Silver Lake	B	11.5 ft	-	-
4	Portage Lake South Basin; Dexter Township	B	13 ft	-	-
5	Little Portage Lake Northeast Basin; Dexter Township	B	11 ft	-	-
6	Base Line Lake	B	11 ft	-	-
7	North Lake	B	12 ft	-	-
8	Little Portage Lake	B	12 ft	-	-
9	Sugarloaf Lake; Lyndon Twp	B	9.5 ft	-	-
10	Pleasant Lake Central Basin; Freedom Township	C	7.2 ft	-	-
11	Pleasant Lake Northwest Basin; Freedom Township	C	5.8 ft	-	-
12	Sugarloaf Lake	C	9.5 ft	-	-
13	Long Lake Southeast Basin; Lyndon Township	C	9 ft	-	-
14	Pleasant Lake	D	6.3 ft	-	-
15	First Sister Lake	F	3 ft	-	-
16	Second Sister Lake	F	3 ft	-	-
17	Ford Lake Central Basin; Ypsilanti Township	F	3 ft	-	-

Source: EPA National Aquatic Resource Surveys, 2026.