Late afternoon sun over Slim Lake, scattering a bright path across wind-textured water

Thurston County Lake Quality

Washington, 29 lakes, average grade D (Nutrient-rich)

There are 29 monitored lakes in Thurston County. The mix is varied enough that the county-level average tells you the broad strokes, not the choose-this-cabin specifics. 12 of those lakes carry an A–F grade. The county-level summary describes that subset, not every water body listed. The county-wide average grade is D — water quality issues are persistent across most of the monitored basins. 1 lakes fall into the F bracket outright.

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. Lake (C) is the cleanest in the county.

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Quick Answers for Thurston County

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Planning a trip? Check special fishing regulations for Lake — or check the official Washington fishing regulations.

All Lakes in Thurston County

29 lakes · 12 graded, 17 not rated12 graded lakes · 17 not rated, hidden

Include not-rated lakes (17)

#	Lake	Grade	Clarity	Phosphorus	Algae	Trophic	Access
1	CLakeThurston	C	No recent samples	7 µg/L	1.3 µg/L	No recent samples	✓ Public
2	CLakeThurston	C	No recent samples	8.5 µg/L	3 µg/L	No recent samples	✓ Public
3	DLakeThurston	D	No recent samples	19.5 µg/L	3.2 µg/L	No recent samples	✓ Public
4	DLakeThurston	D	No recent samples	14.5 µg/L	3 µg/L	No recent samples	✓ Public
5	DLakeThurston	D	No recent samples	28 µg/L	8.3 µg/L	No recent samples	✓ Public
6	DLakeThurston	D	No recent samples	31 µg/L	17 µg/L	No recent samples	Not recorded
7	DLakeThurston	D	No recent samples	20.5 µg/L	6.1 µg/L	No recent samples	✓ Public
8	DLakeThurston	D	No recent samples	24.5 µg/L	14 µg/L	No recent samples	Not recorded
9	DLakeThurston	D	No recent samples	25.5 µg/L	6.1 µg/L	No recent samples	Not recorded
10	DLakeThurston	D	No recent samples	29.5 µg/L	9.4 µg/L	No recent samples	✓ Public
11	DLakeThurston	D	No recent samples	26 µg/L	7.2 µg/L	No recent samples	✓ Public
12	FLakeThurston	F	No recent samples	126.5 µg/L	34 µg/L	No recent samples	✓ Public
	NRLakeThurston	NR	No recent samples	32 µg/L	2.7 µg/L	No recent samples	Not recorded
	NRLakeThurston	NR	No recent samples	33 µg/L	7.5 µg/L	No recent samples	Not recorded
	NRLakeThurston	NR	No recent samples	27 µg/L	11.6 µg/L	No recent samples	Not recorded
	NRBald Hill LakeThurston	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRAlder LakeThurston	NR	No recent samples	No recent samples	No recent samples	No recent samples	✓ Public
	NRLa Grande ReservoirThurston	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRElbow LakeThurston	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRSkookumchuck ReservoirThurston	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRScott LakeThurston	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRPitman LakeThurston	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRMunn LakeThurston	NR	No recent samples	No recent samples	No recent samples	No recent samples	✓ Public
	NRSimmons LakeThurston	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRHewitt LakeThurston	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRChambers LakeThurston	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRPattison LakeThurston	NR	No recent samples	No recent samples	No recent samples	No recent samples	✓ Public
	NRTempo LakeThurston	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRMcIntosh LakeThurston	NR	No recent samples	No recent samples	No recent samples	No recent samples	✓ Public

NR = not rated: there is not enough recent sampling to support a letter. That is EPA Integrated Reporting Category 3 (insufficient information), not a failing grade. How grading works.

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Other Counties in Washington

Lincoln County

22 lakes · Avg grade A

Grant County

48 lakes · Avg grade A

Whatcom County

34 lakes · Avg grade B

Yakima County

23 lakes · Avg grade C

Snohomish County

52 lakes · Avg grade C

Kitsap County

12 lakes · Not rated

See how Thurston County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all United States (49 states), Canada (Ontario, Québec, Nova Scotia, British Columbia and Newfoundland and Labrador), and 38 other country hubs..

Source: EPA National Aquatic Resource Surveys, 2026.