Mesotrophic Lakes in Washington

12 mesotrophic lakes in Washington. 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. 12 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	Lake: Ward Lake	Thurston	A	-	-	40
2	Nla Lake	Grant	A	12.8 ft	-	41
3	Nla Lake	Mason	A	-	-	47
4	Spearhead Lake	Skagit	A	10.8 ft	-	43
5	Lake: Hicks Lake	Thurston	A	-	-	48
6	Nla Lake	Douglas	B	13 ft	-	49
7	Lake Sammamish	King	B	11.5 ft	-	42
8	Stickney Lake	Snohomish	B	11.8 ft	-	42
9	Liberty Lake	Spokane	B	13 ft	-	40
10	Spokane Arm -Potential Discharge Location Lake	Stevens	B	-	-	47
11	Moses Lake	Grant	B	-	-	47
12	Nla Lake	Jefferson	B	9.7 ft	-	49

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 →Idaho version →Montana version →New Mexico version →Tennessee version →Alabama version →Virginia version →Kentucky version →Utah version →Wyoming version →All Washington lakes →

Source: EPA National Aquatic Resource Surveys, 2026.