What are eutrophic lakes in Idaho?

9 eutrophic lakes in Idaho. High nutrients, frequent algae, reduced clarity.

What does eutrophic mean?

High nutrients, frequent algae, reduced clarity.

Eutrophic Lakes in Idaho

A eutrophic lake is a productive ecosystem with the trade-offs that come with productivity: more food at the base of the food web, more clarity reduction by mid-summer, more dissolved-oxygen variability near the bottom. 9 Idaho lakes register as eutrophic. Only 0% are deep — eutrophy correlates with shallowness, agricultural watersheds, and the kind of nutrient-input history that takes decades to shift.

Eutrophic lakes typically grade C or D on our A–F scale. The same nutrient richness that defines the trophic class drives the lower grade.

#	Lake	County	Grade	Clarity	Depth	TSI
1	Mud Lake	Bear Lake	C	-	-	59
2	Cas Reservoir Inlet Between Lf And	Valley	D	4.3 ft	-	56
3	Lake Walcott	Cassia	D	4.3 ft	-	58
4	Island Park Lake	Fremont	D	9.8 ft	-	50
5	Cascade R W of Sugarloaf Island Lake	Valley	D	8.2 ft	-	50
6	Island Pk Reservoir	Fremont	D	2.3 ft	-	60
7	Littlewood Lake	Blaine	D	12.5 ft	-	50
8	Mountain View Lake	Owyhee	D	-	-	57
9	American Falls R-Little Hole Draw Lake	Power	D	-	-	60

All eutrophic 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 →Georgia version →Massachusetts version →Ontario version →Québec version →Nova Scotia version →British Columbia version →Newfoundland and Labrador version →All Idaho lakes →

Source: EPA National Aquatic Resource Surveys, 2026.