Mesotrophic Lakes in Idaho

26 mesotrophic lakes in Idaho. Moderate nutrients, good water quality.

Mesotrophic lakes are the productive middle of the trophic scale — TSI between 40 and 50. Clear enough to be inviting, productive enough to support a strong fishery, with moderate phosphorus and a modest algal community that does not dominate the optical signal. 26 lakes in {{stateName}} sit in the mesotrophic band. About 0% are deep (50+ ft); the rest are shallower basins where watershed management keeps nutrients from pushing the system into eutrophy.

Mesotrophic lakes tend to grade B or C on the LakeGrade rubric — the productive-but-clear band lines up with the middle of the letter grades.

#	Lake	County	Grade	Clarity	Depth	TSI
1	Nla Lake	Valley	A	-	-	45
2	Ririe Reservoir	Bonneville	A	-	-	44
3	Cat Creek Lake	Elmore	A	-	-	45
4	Cat Creek Reference Lake	Elmore	A	-	-	46
5	Pasisades Reservoir	Bonneville	A	10.5 ft	-	42
6	Palisades Reservoir	Bonneville	A	12.5 ft	-	41
7	Deadwood Res Off Face of Dam Lake	Valley	A	-	-	45
8	Nla Lake	Bonner	B	6.9 ft	-	42
9	Palisades Lake	Bonneville	B	13.1 ft	-	42
10	Lake Lowell	Canyon	B	7.2 ft	-	43
11	Arrowrock Reservoir	Elmore	B	12.5 ft	-	44
12	Nla Lake	Adams	B	12.5 ft	-	46
13	Nla Lake	Owyhee	B	10.8 ft	-	47
14	Nla Lake	Gooding	B	-	-	43
15	Black Cnyn Reservoir Ns of	Gem	B	7.5 ft	-	48
16	Cascade Reservoir A Sugar Loaf Island	Valley	B	8.5 ft	-	43
17	Chatcolet Lake	Benewah	B	-	-	49
18	Nla Lake	Bingham	B	8.1 ft	-	50
19	Waha Reservoir Middle	Nez Perce	B	9.7 ft	-	49
20	Cascade R W of Sugarloaf Island Lake	Valley	B	8.2 ft	-	50
21	Littlewood Lake	Blaine	B	12.5 ft	-	50
22	Cascade Reservoir	Valley	B	8.2 ft	-	44
23	Lake Lowell Across From Upper Embankment	Canyon	B	7.2 ft	-	49
24	Cascade R Lake	Valley	C	9.2 ft	-	49
25	Island Park Lake	Fremont	C	9.8 ft	-	50
26	Nla Lake	Cassia	C	3 ft	-	46

All mesotrophic lakes →Minnesota version →Wisconsin version →Illinois version →Michigan version →Iowa version →Ohio version →Pennsylvania version →New York version →Missouri version →Indiana version →North Dakota version →South Dakota version →Florida version →Colorado version →North Carolina version →Vermont version →Texas version →Oregon version →Arkansas version →Oklahoma version →Kansas version →Nebraska version →Nevada version →Arizona version →Montana version →New Mexico version →Tennessee version →Alabama version →Virginia version →Kentucky version →Utah version →Washington version →Wyoming version →All Idaho lakes →

Source: EPA National Aquatic Resource Surveys, 2026.