Cass County Lake Quality

Minnesota, 130 lakes, average grade A (Excellent)

Cass County has 130 graded lakes, enough that within-county variation matters as much as the county average. Some are deep glacial basins, others are shallow agricultural-watershed waters, and the grade distribution reflects that mix. On average, Cass County lakes grade an A. That puts it near the top of the Minnesota county ranking.

A meaningful share of Cass's lakes break 50 feet of depth, which matters because deep lakes hold cooler water all summer and resist the resuspended-sediment problems that plague shallow basins. The county's best-graded lake is Rainy Lake (A).

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Quick Answers for Cass County

Cleanest lakes in Cass County →Cleanest lakes in Minnesota →Safest swimming lakes in Minnesota →

Planning a trip? Check special fishing regulations for Rainy Lake — or browse the full Minnesota regulations index.

Fishing in Cass County

Cass County Fishing Guide

Fish species and best-graded lakes in Cass County

DNR Reports (40)

Minnesota DNR LakeFinder resources for lakes in Cass County. browse all reports →

These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).

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Fisheries Lake Survey — Widow
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Welch
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Webb
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Washburn
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Wabedo
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Vermillion
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Variety
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Upper Trelipe
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Upper Sucker
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Upper Gull
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Trillium
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Town Line
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Thunder
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Three Island
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Ten Mile
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Swift
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Sugar
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Stony
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Stevens
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Steamboat
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Leech
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Spider
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Six Mile
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Silver
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Sand
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Sanborn
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Roosevelt
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Rock
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Ray
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Rainy
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Portage
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Portage
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Portage
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Ponto
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Pleasant
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Pine Mountain
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Pine
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Pillager
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Ox Yoke
Fisheries Lake Survey · MN DNR LakeFinder
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Fisheries Lake Survey — Norway
Fisheries Lake Survey · MN DNR LakeFinder

All Lakes in Cass County

130 lakes · 103 graded, 27 not rated103 graded lakes · 27 not rated, hidden

Include not-rated lakes (27)

#	Lake	Grade	Clarity	Phosphorus	Algae	Trophic	Max Depth	Access
1	ARainy LakeCass	A	13.9 ft	11.5 µg/L	1.8 µg/L	No recent samples	29 ft	Carry-in
2	ADeep Portage LakeCass	A	15.4 ft	9 µg/L	1.6 µg/L	No recent samples	105 ft	Carry-in
3	ABirch LakeCass	A	14 ft	12 µg/L	4 µg/L	No recent samples	45 ft	✓ Public
4	AAda LakeCass	A	14 ft	10 µg/L	2.7 µg/L	No recent samples	60 ft	✓ Public
5	AHorseshoe LakeCass	A	8.9 ft	18 µg/L	2.7 µg/L	No recent samples	12 ft	✓ Public
6	AWashburn LakeCass	A	14.1 ft	11 µg/L	3.7 µg/L	No recent samples	111 ft	✓ Public
7	ALong LakeCass	A	21.5 ft	9 µg/L	3 µg/L	No recent samples	115 ft	✓ Public
8	AMaple LakeCass	A	13.3 ft	11 µg/L	2.2 µg/L	No recent samples	45 ft	Carry-in
9	ANorway LakeCass	A	6.9 ft	21 µg/L	5.1 µg/L	No recent samples	12 ft	✓ Public
10	AWoman LakeCass	A	15 ft	11 µg/L	3.2 µg/L	No recent samples	No recent samples	✓ Public
11	AGirl LakeCass	A	17.6 ft	12 µg/L	2.7 µg/L	No recent samples	81 ft	✓ Public
12	AUpper Gull LakeCass	A	9.5 ft	20 µg/L	5.6 µg/L	No recent samples	54 ft	Carry-in
13	ALeech LakeCass	A	12.5 ft	12 µg/L	2.7 µg/L	No recent samples	No recent samples	✓ Public
14	AIsland LakeCass	A	15.5 ft	21.5 µg/L	2.6 µg/L	No recent samples	45 ft	✓ Public
15	AIsland LakeCass	A	17.5 ft	9 µg/L	2.7 µg/L	No recent samples	40 ft	✓ Public
16	AIsland LakeCass	A	8.2 ft	20 µg/L	3.9 µg/L	No recent samples	No recent samples	Carry-in
17	ACrooked LakeCass	A	12 ft	13 µg/L	4 µg/L	No recent samples	74 ft	Carry-in
18	APortage LakeCass	A	7 ft	20 µg/L	5.9 µg/L	No recent samples	No recent samples	Carry-in
19	ASpider LakeCass	A	10.2 ft	12.5 µg/L	5 µg/L	No recent samples	17 ft	✓ Public
20	AGull LakeCass	A	15 ft	13.5 µg/L	3 µg/L	No recent samples	80 ft	✓ Public
21	AUpper Trelipe LakeCass	A	14 ft	12 µg/L	3.1 µg/L	No recent samples	69 ft	✓ Public
22	ARay LakeCass	A	10.3 ft	11.5 µg/L	3 µg/L	No recent samples	27 ft	✓ Public
23	ALawrence LakeCass	A	9.8 ft	17 µg/L	4.8 µg/L	No recent samples	71 ft	✓ Public
24	ASilver LakeCass	A	13 ft	14 µg/L	4.5 µg/L	No recent samples	20 ft	✓ Public
25	AChild LakeCass	A	12.1 ft	14 µg/L	3.7 µg/L	No recent samples	29 ft	✓ Public
26	ABaby LakeCass	A	12.5 ft	10 µg/L	2.9 µg/L	No recent samples	69 ft	✓ Public
27	AInguadona LakeCass	A	12 ft	15 µg/L	4.5 µg/L	No recent samples	79 ft	✓ Public
28	ACrystal LakeCass	A	16 ft	7.5 µg/L	2.3 µg/L	No recent samples	40 ft	✓ Public
29	APleasant LakeCass	A	15.5 ft	10 µg/L	3.1 µg/L	No recent samples	72 ft	✓ Public
30	ARoosevelt LakeCass	A	11.1 ft	12.5 µg/L	3.6 µg/L	No recent samples	129 ft	✓ Public
31	AWebb LakeCass	A	18 ft	9.5 µg/L	2.9 µg/L	No recent samples	84 ft	✓ Public
32	ABroadwater Bay LakeCass	A	14.4 ft	13.5 µg/L	3.6 µg/L	No recent samples	54 ft	✓ Public
33	ABlackwater LakeCass	A	14.1 ft	12 µg/L	4 µg/L	No recent samples	67 ft	✓ Public
34	AHoward LakeCass	A	16 ft	9 µg/L	1.7 µg/L	No recent samples	60 ft	Carry-in
35	AMan LakeCass	A	11 ft	10 µg/L	2.7 µg/L	No recent samples	93 ft	Carry-in
36	ALittle Boy LakeCass	A	11 ft	14 µg/L	5.1 µg/L	No recent samples	74 ft	✓ Public
37	AThunder LakeCass	A	16.5 ft	10 µg/L	2.4 µg/L	No recent samples	95 ft	✓ Public
38	ALittle Portage LakeCass	A	16.4 ft	12 µg/L	2.7 µg/L	No recent samples	No recent samples	Carry-in
39	APine LakeCass	A	16 ft	14 µg/L	3.2 µg/L	No recent samples	25 ft	✓ Public
40	AThree Island LakeCass	A	9 ft	12 µg/L	3.3 µg/L	No recent samples	13 ft	✓ Public
41	ATen Mile LakeCass	A	20.5 ft	8.5 µg/L	1.9 µg/L	No recent samples	208 ft	✓ Public
42	APonto LakeCass	A	19 ft	8 µg/L	2.1 µg/L	No recent samples	60 ft	✓ Public
43	AWabedo LakeCass	A	10.5 ft	16 µg/L	4.9 µg/L	No recent samples	95 ft	✓ Public
44	ALittle Sand LakeCass	A	7.5 ft	22.5 µg/L	5.6 µg/L	No recent samples	12 ft	✓ Public
45	ALoon LakeCass	A	12.1 ft	14 µg/L	3.5 µg/L	No recent samples	25 ft	✓ Public
46	ASylvan LakeCass	A	19.5 ft	7 µg/L	2.1 µg/L	No recent samples	No recent samples	Carry-in
47	AHunter LakeCass	A	31 ft	11 µg/L	1.7 µg/L	No recent samples	48 ft	✓ Public
48	ASugar LakeCass	A	13.5 ft	18 µg/L	7 µg/L	No recent samples	44 ft	✓ Public
49	AHattie LakeCass	A	10.3 ft	16.5 µg/L	4.5 µg/L	No recent samples	30 ft	Carry-in
50	ALost LakeCass	A	14.8 ft	10.5 µg/L	2.3 µg/L	No recent samples	26 ft	Carry-in
51	ABoy LakeCass	A	10.5 ft	21 µg/L	6.3 µg/L	No recent samples	45 ft	✓ Public
52	AStony LakeCass	A	23 ft	7 µg/L	2 µg/L	No recent samples	50 ft	✓ Public
53	ASteamboat LakeCass	A	12 ft	11 µg/L	3.4 µg/L	No recent samples	93 ft	✓ Public
54	ABig Portage (E Bay LakeCass	A	8.9 ft	19 µg/L	6.4 µg/L	No recent samples	23 ft	✓ Public
55	ALeavitt LakeCass	A	7.9 ft	19 µg/L	5.3 µg/L	No recent samples	60 ft	✓ Public
56	ABarnum LakeCass	A	16.1 ft	9 µg/L	3 µg/L	No recent samples	30 ft	✓ Public
57	AMule LakeCass	A	18 ft	10 µg/L	2.4 µg/L	No recent samples	47 ft	✓ Public
58	APillager LakeCass	A	15.1 ft	9 µg/L	2.9 µg/L	No recent samples	39 ft	✓ Public
59	ADade LakeCass	A	5.2 ft	12 µg/L	2 µg/L	No recent samples	No recent samples	✓ Public
60	ABig Portage (W Bay LakeCass	A	8.5 ft	18.5 µg/L	5.6 µg/L	No recent samples	23 ft	✓ Public
61	APine Mountain LakeCass	A	12.5 ft	17.5 µg/L	2.3 µg/L	No recent samples	80 ft	✓ Public
62	ACooper LakeCass	A	17.1 ft	13 µg/L	3.1 µg/L	No recent samples	70 ft	Carry-in
63	ASwift LakeCass	A	8.5 ft	13 µg/L	4.9 µg/L	No recent samples	52 ft	Carry-in
64	ASteamboat Bay LakeCass	A	9.8 ft	15 µg/L	3 µg/L	No recent samples	150 ft	✓ Public
65	AMckeown LakeCass	A	16.1 ft	11 µg/L	2.7 µg/L	No recent samples	37 ft	✓ Public
66	AKid LakeCass	A	15.5 ft	11.5 µg/L	3.3 µg/L	No recent samples	52 ft	Carry-in
67	AHay LakeCass	A	13.2 ft	16.5 µg/L	2.4 µg/L	No recent samples	56 ft	✓ Public
68	ABoy Bay LakeCass	A	7.4 ft	13 µg/L	3.6 µg/L	No recent samples	No recent samples	✓ Public
69	AShingobee Bay LakeCass	A	10.6 ft	19.5 µg/L	6.3 µg/L	No recent samples	No recent samples	✓ Public
70	APortage Bay LakeCass	A	11.3 ft	15 µg/L	4.9 µg/L	No recent samples	No recent samples	✓ Public
71	ATraders Bay LakeCass	A	10 ft	18.5 µg/L	3.8 µg/L	No recent samples	No recent samples	✓ Public
72	AHeadquarters Bay LakeCass	A	7.5 ft	16.5 µg/L	3.6 µg/L	No recent samples	No recent samples	✓ Public
73	ASucker Bay LakeCass	A	8.8 ft	17 µg/L	3.6 µg/L	No recent samples	No recent samples	✓ Public
74	AWalker Bay LakeCass	A	16.5 ft	10 µg/L	1.7 µg/L	No recent samples	No recent samples	✓ Public
75	AAgency Bay LakeCass	A	15.2 ft	11 µg/L	2.5 µg/L	No recent samples	No recent samples	✓ Public
76	AKabekona Bay LakeCass	A	17.2 ft	10 µg/L	2.7 µg/L	No recent samples	150 ft	✓ Public
77	ABoxell LakeCass	A	14.5 ft	14 µg/L	3.6 µg/L	No recent samples	27 ft	Carry-in
78	AUpper Sucker LakeCass	A	10.8 ft	19 µg/L	6.3 µg/L	No recent samples	25 ft	Carry-in
79	ALower Sucker LakeCass	A	8.3 ft	21 µg/L	6.5 µg/L	No recent samples	35 ft	✓ Public
80	AFive Point LakeCass	A	12.8 ft	19 µg/L	2.6 µg/L	No recent samples	37 ft	✓ Public
81	ASix Mile LakeCass	A	11.5 ft	14.5 µg/L	6.7 µg/L	No recent samples	68 ft	✓ Public
82	AWelsh LakeCass	A	12.5 ft	12 µg/L	4.2 µg/L	No recent samples	59 ft	✓ Public
83	AJack LakeCass	A	15.7 ft	9 µg/L	3.1 µg/L	No recent samples	110 ft	✓ Public
84	ABig Deep LakeCass	A	19.4 ft	7 µg/L	1.9 µg/L	No recent samples	107 ft	Carry-in
85	AWelch LakeCass	A	12.5 ft	11 µg/L	3.9 µg/L	No recent samples	59 ft	✓ Public
86	ACass Lake Pike BayCass	A	13.6 ft	10.5 µg/L	3.4 µg/L	No recent samples	95 ft	✓ Public
87	CPortage LakeCass	C	7.5 ft	22 µg/L	7.1 µg/L	No recent samples	55 ft	✓ Public
88	CGeorge LakeCass	C	5 ft	40 µg/L	7.3 µg/L	No recent samples	20 ft	✓ Public
89	CRock LakeCass	C	5.9 ft	29.5 µg/L	10.9 µg/L	No recent samples	17 ft	✓ Public
90	CLower Trelipe LakeCass	C	6.9 ft	23 µg/L	11.9 µg/L	No recent samples	32 ft	✓ Public
91	CFaherty LakeCass	C	6.2 ft	26.5 µg/L	10.7 µg/L	No recent samples	No recent samples	✓ Public
92	CGould LakeCass	C	5 ft	13.5 µg/L	1.9 µg/L	No recent samples	No recent samples	Carry-in
93	CBowen LakeCass	C	13.7 ft	30 µg/L	2.6 µg/L	No recent samples	25 ft	✓ Public
94	CTown Line LakeCass	C	6.6 ft	11 µg/L	2.1 µg/L	No recent samples	11 ft	✓ Public
95	CBueber LakeCass	C	6.2 ft	37 µg/L	6.2 µg/L	No recent samples	32 ft	✓ Public
96	CStevens LakeCass	C	10.2 ft	28.5 µg/L	5.8 µg/L	No recent samples	63 ft	✓ Public
97	CLake WinnibigoshishCass	C	12.1 ft	29 µg/L	5.2 µg/L	No recent samples	69.8 ft	✓ Public
98	CVermillion LakeCass	C	12.6 ft	25 µg/L	10 µg/L	No recent samples	27 ft	✓ Public
99	CTamarack Bay LakeCass	C	11.5 ft	26 µg/L	4.6 µg/L	No recent samples	69.8 ft	✓ Public
100	CLittle Wolf LakeCass	C	7 ft	26.5 µg/L	12.7 µg/L	No recent samples	24 ft	✓ Public
101	DMargaret LakeCass	D	5.5 ft	38.5 µg/L	21.5 µg/L	No recent samples	26 ft	Carry-in
102	DMiddle Sucker LakeCass	D	4.8 ft	34 µg/L	17.7 µg/L	No recent samples	20 ft	Carry-in
103	DMiddle Sucker LakeCass	D	4.8 ft	35 µg/L	17.5 µg/L	No recent samples	No recent samples	Carry-in
	NRHorseshoe LakeCass	NR	21 ft	No recent samples	No recent samples	No recent samples	51 ft	✓ Public
	NRLong LakeCass	NR	17 ft	No recent samples	No recent samples	No recent samples	37 ft	✓ Public
	NRSand LakeCass	NR	20 ft	No recent samples	No recent samples	No recent samples	54 ft	✓ Public
	NRLeech LakeCass	NR	9 ft	No recent samples	No recent samples	No recent samples	No recent samples	✓ Public
	NRBass LakeCass	NR	No recent samples	9 µg/L	2 µg/L	No recent samples	55 ft	✓ Public
	NRPortage LakeCass	NR	21 ft	No recent samples	No recent samples	No recent samples	84 ft	Carry-in
	NRPortage LakeCass	NR	12 ft	No recent samples	No recent samples	No recent samples	65 ft	✓ Public
	NRKidney LakeCass	NR	11.5 ft	No recent samples	No recent samples	No recent samples	55 ft	Carry-in
	NRHand LakeCass	NR	17 ft	No recent samples	No recent samples	No recent samples	57 ft	✓ Public
	NROx Yoke LakeCass	NR	17.5 ft	No recent samples	No recent samples	No recent samples	42 ft	✓ Public
	NRSanburn LakeCass	NR	19 ft	No recent samples	No recent samples	No recent samples	48 ft	✓ Public
	NRTrillium LakeCass	NR	11.2 ft	17 µg/L	3.1 µg/L	No recent samples	48 ft	Carry-in
	NRAndrus LakeCass	NR	12 ft	No recent samples	No recent samples	No recent samples	55 ft	Carry-in
	NRLittle Andrus LakeCass	NR	13 ft	No recent samples	No recent samples	No recent samples	37 ft	✓ Public
	NRWidow LakeCass	NR	18.5 ft	No recent samples	No recent samples	No recent samples	46 ft	✓ Public
	NRVariety LakeCass	NR	10.8 ft	No recent samples	No recent samples	No recent samples	29 ft	Carry-in
	NRLittle Webb LakeCass	NR	16.5 ft	No recent samples	No recent samples	No recent samples	37 ft	✓ Public
	NRL Thunder LakeCass	NR	14 ft	No recent samples	No recent samples	No recent samples	No recent samples	✓ Public
	NRFawn LakeCass	NR	20 ft	No recent samples	No recent samples	No recent samples	29 ft	✓ Public
	NRThunder LakeCass	NR	20 ft	No recent samples	No recent samples	No recent samples	95 ft	✓ Public
	NRBlackwater LakeCass	NR	13.1 ft	No recent samples	No recent samples	No recent samples	67 ft	✓ Public
	NRGrave LakeCass	NR	17.2 ft	No recent samples	No recent samples	No recent samples	55 ft	✓ Public
	NRInguadona LakeCass	NR	12.5 ft	No recent samples	No recent samples	No recent samples	79 ft	✓ Public
	NRLong LakeCass	NR	21.5 ft	No recent samples	No recent samples	No recent samples	115 ft	✓ Public
	NRAbel LakeCass	NR	5.7 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRMillion LakeCass	NR	5 ft	21 µg/L	3.8 µg/L	No recent samples	20 ft	Carry-in
	NRPine Mountain LakeCass	NR	17.5 ft	No recent samples	No recent samples	No recent samples	80 ft	✓ Public

NR = not rated: the monitoring record does not meet the evidence bar for a grade. That is EPA Integrated Reporting Category 3 (insufficient information), not a failing grade. How grading works.

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