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

Flathead County Lake Quality

Montana, 108 lakes, measured by Montana DEQ

Flathead County has 108 monitored 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 measurements reflect that mix. 9 of those lakes carry recent nutrient and algae readings. The county-level summary describes that subset, not every water body listed. The county-wide picture is low-to-moderate phosphorus with clear summer transparency across most monitored lakes.

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. Tally Lake has the lowest nutrient and algae readings in the county.

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Quick Answers for Flathead County

Cleanest lakes in Flathead County →Cleanest lakes in Montana →Best swimming lakes in Montana →

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

All Lakes in Flathead County

108 lakes · 9 ranked on readings, 99 without enough sampling9 lakes ranked on readings · 99 without enough sampling, hidden

Include not-rated lakes (99)

#	Lake	Clarity	Phosphorus	Algae	Trophic	Max Depth	Access
1	Tally LakeFlathead	15.2 ft	4.7 µg/L	0.8 µg/L	No recent samples	No recent samples	Not recorded
2	Whitefish LakeFlathead	22 ft	2.8 µg/L	0.9 µg/L	No recent samples	No recent samples	✓ Public
3	Smith LakeFlathead	No recent samples	7.4 µg/L	0.8 µg/L	No recent samples	No recent samples	Not recorded
4	Little Bitterroot Lake CenterFlathead	No recent samples	4 µg/L	1 µg/L	No recent samples	No recent samples	Not recorded
5	Mcgilvray LakeFlathead	No recent samples	5.9 µg/L	1.7 µg/L	No recent samples	No recent samples	Not recorded
6	Hanson-Doyle LakeFlathead	No recent samples	7.3 µg/L	2.3 µg/L	No recent samples	No recent samples	Not recorded
7	Bailey LakeFlathead	No recent samples	6.9 µg/L	2 µg/L	No recent samples	No recent samples	Not recorded
8	Foys LakeFlathead	No recent samples	15.8 µg/L	4.1 µg/L	No recent samples	No recent samples	Not recorded
9	Rogers LakeFlathead	No recent samples	11.6 µg/L	2.6 µg/L	No recent samples	No recent samples	Not recorded
	Halfmoon LakeFlathead	17.8 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Spencer LakeFlathead	13.5 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Lost Coon LakeFlathead	11.8 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Bailey LakeFlathead	19.5 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Blanchard LakeFlathead	19 ft	No recent samples	No recent samples	No recent samples	No recent samples	✓ Public
	Echo LakeFlathead	15.2 ft	No recent samples	No recent samples	No recent samples	No recent samples	✓ Public
	Rogers LakeFlathead	13.6 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Dickey LakeFlathead	17.7 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Mcgilvray LakeFlathead	21 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Fish LakeFlathead	16.6 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Lower Stillwater LakeFlathead	21 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Skyles LakeFlathead	17 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Beaver LakeFlathead	18.8 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Upper Whitefish LakeFlathead	20.5 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Bootjack LakeFlathead	20.8 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Foy LakeFlathead	17.5 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Lake BlaineFlathead	17.1 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Ashley LakeFlathead	33.1 ft	No recent samples	No recent samples	No recent samples	No recent samples	✓ Public
	Hanson-Doyle LakeFlathead	21.8 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Abbot LakeFlathead	15 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Peterson LakeFlathead	14.9 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Lake FiveFlathead	16 ft	No recent samples	No recent samples	No recent samples	No recent samples	✓ Public
	Murray LakeFlathead	22 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Dollar LakeFlathead	19.2 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Upper Stillwater LakeFlathead	21.9 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Lake of the WoodsFlathead	No recent samples	5 µg/L	0.1 µg/L	No recent samples	No recent samples	Not recorded
	Lake McdonaldFlathead	No recent samples	No recent samples	0.7 µg/L	No recent samples	No recent samples	Not recorded
	Lost Loon LakeFlathead	No recent samples	10.1 µg/L	2.6 µg/L	No recent samples	No recent samples	Not recorded
	Hubbart ReservoirFlathead	No recent samples	No recent samples	No recent samples	No recent samples	73 ft	Not recorded
	Little McGregor LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	McGregor LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Lynch LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Dahl LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Pearson ReservoirFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Smith LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	✓ Public
	Lake MonroeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Lone LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Middle Foy LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	McWenneger SloughFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Egan SloughFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Church SloughFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Wileys SloughFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Fennon SloughFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Lake of the WoodsFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Mud LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Margaret LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Handkerchief LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Pilgrim LakesFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Birch LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Black LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Wildcat LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Clayton LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Hungry Horse ReservoirFlathead	No recent samples	No recent samples	No recent samples	No recent samples	490 ft	Not recorded
	Lion LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Lore LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Bowser LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Boyle LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Spoon LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Harrison LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Lincoln LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Lake Ellen WilsonFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Avalanche LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Logging LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Trout LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Arrow LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Lake EvangelineFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Ruger LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Cerulean LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Gyrfalcon LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Grace LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Lower Quartz LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Middle Quartz LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Quartz LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Bowman LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Winona LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Cyclone LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Finger LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Duck LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Dog LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Tepee LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Long Bow LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Upper Kintla LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Pocket LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Hidden LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Buffalo Woman LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Beaver Woman LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Striped Elk LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Lake IsabelFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Stanton LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Marion LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Moose LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Elk LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Bradley LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Flotilla LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Scott LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Sunburst LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Palisade LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Mud LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Big Salmon LakeFlathead	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded

NR = no nutrient or algae reading on record. The measurements are published as the authority reports them. Where the data comes from.

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Source: the Montana Department of Environmental Quality. See data sources.