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

Coos County Lake Quality

New Hampshire, 51 lakes, measured by NHDES

Coos County has 51 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. 13 of those lakes carry recent nutrient and algae readings. The county-level summary describes that subset, not every water body listed. Most monitored lakes in Coos County carry favourable nutrient and algae readings for New Hampshire.

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. Akers Pond-Deep Spot has the lowest nutrient and algae readings in the county.

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Quick Answers for Coos County

Cleanest lakes in Coos County →Best swimming lakes in New Hampshire →

Planning a trip? Check special fishing regulations for Akers Pond-Deep Spot — or check the official New Hampshire fishing regulations.

All Lakes in Coos County

51 lakes · 13 ranked on readings, 38 without enough sampling13 lakes ranked on readings · 38 without enough sampling, hidden

Include not-rated lakes (38)

#	Lake	Clarity	Phosphorus	Algae	Trophic	Max Depth	Access
1	Akers Pond-Deep SpotCoos	No recent samples	9 µg/L	No recent samples	No recent samples	No recent samples	✓ Public
2	Big Dummer Pond-Deep SpotCoos	No recent samples	10.5 µg/L	No recent samples	No recent samples	No recent samples	Not recorded
3	Forest Lake-Deep SpotCoos	No recent samples	10 µg/L	4.6 µg/L	No recent samples	No recent samples	Not recorded
4	Forest Lake-FinkelCoos	No recent samples	10.6 µg/L	No recent samples	No recent samples	No recent samples	Not recorded
5	Forest Lake-Newt CottageCoos	No recent samples	7.7 µg/L	No recent samples	No recent samples	No recent samples	✓ Public
6	Forest Lake-Sundman CottageCoos	No recent samples	8.9 µg/L	No recent samples	No recent samples	No recent samples	Not recorded
7	Jericho Lake-Deep SpotCoos	No recent samples	13 µg/L	No recent samples	No recent samples	No recent samples	✓ Public
8	Little Dummer Pond-Deep SpotCoos	No recent samples	9.6 µg/L	No recent samples	No recent samples	No recent samples	Not recorded
9	Martin Meadow Pond-MccartenCoos	No recent samples	6.5 µg/L	No recent samples	No recent samples	No recent samples	Not recorded
10	Martin Meadow Pond-WeeksCoos	No recent samples	6.6 µg/L	No recent samples	No recent samples	No recent samples	Not recorded
11	Martin Meadow Pond-WhithedCoos	No recent samples	5.6 µg/L	No recent samples	No recent samples	No recent samples	✓ Public
12	Stratford Bog Pond-Deep SpotCoos	No recent samples	8.8 µg/L	No recent samples	No recent samples	No recent samples	Not recorded
13	Martin Meadow Pond-Deep SpotCoos	No recent samples	17.1 µg/L	3.1 µg/L	No recent samples	No recent samples	Not recorded
	Back LakeCoos	No recent samples	No recent samples	No recent samples	No recent samples	15 ft	Not recorded
	Back PondCoos	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	✓ Public
	Big Brook BogCoos	No recent samples	No recent samples	No recent samples	No recent samples	5 ft	Not recorded
	Burns Pond-Deep SpotCoos	No recent samples	13.6 µg/L	5.5 µg/L	No recent samples	No recent samples	✓ Public
	Cedar PondCoos	No recent samples	No recent samples	No recent samples	No recent samples	50 ft	✓ Public
	Cherry PondCoos	No recent samples	No recent samples	No recent samples	No recent samples	4.3 ft	Not recorded
	Christine LakeCoos	No recent samples	No recent samples	No recent samples	No recent samples	65 ft	Not recorded
	Diamond PondCoos	No recent samples	No recent samples	No recent samples	No recent samples	100 ft	✓ Public
	East Inlet FlowageCoos	No recent samples	No recent samples	No recent samples	No recent samples	5 ft	Not recorded
	First Connecticut Lake-Deep SpotCoos	No recent samples	7.4 µg/L	No recent samples	No recent samples	No recent samples	✓ Public
	Fish PondCoos	No recent samples	No recent samples	No recent samples	No recent samples	5 ft	✓ Public
	Greenough PondCoos	No recent samples	No recent samples	No recent samples	No recent samples	103 ft	Not recorded
	Head PondCoos	No recent samples	No recent samples	No recent samples	No recent samples	7.9 ft	Not recorded
	Lake FrancisCoos	No recent samples	No recent samples	No recent samples	No recent samples	82 ft	✓ Public
	Lake GlorietteCoos	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Little Bog PondCoos	No recent samples	No recent samples	No recent samples	No recent samples	10 ft	Not recorded
	Little Diamond PondCoos	No recent samples	No recent samples	No recent samples	No recent samples	10 ft	✓ Public
	Little Greenough PondCoos	No recent samples	No recent samples	No recent samples	No recent samples	10 ft	Not recorded
	Long PondCoos	No recent samples	No recent samples	No recent samples	No recent samples	10 ft	Not recorded
	Millsfield PondCoos	No recent samples	No recent samples	No recent samples	No recent samples	14 ft	✓ Public
	Mirror LakeCoos	No recent samples	No recent samples	No recent samples	No recent samples	20 ft	✓ Public
	Moose PondCoos	No recent samples	No recent samples	No recent samples	No recent samples	10 ft	Not recorded
	Mud PondCoos	No recent samples	No recent samples	No recent samples	No recent samples	7.9 ft	Not recorded
	Munn PondCoos	No recent samples	No recent samples	No recent samples	No recent samples	30 ft	Not recorded
	Nay PondCoos	No recent samples	No recent samples	No recent samples	No recent samples	5 ft	✓ Public
	Phillips PondCoos	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Pontook ReservoirCoos	No recent samples	No recent samples	No recent samples	No recent samples	15 ft	Not recorded
	Reflection PondCoos	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	✓ Public
	Round PondCoos	No recent samples	No recent samples	No recent samples	No recent samples	40 ft	Not recorded
	Scott BogCoos	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Second Connecticut LakeCoos	No recent samples	No recent samples	No recent samples	No recent samples	60 ft	✓ Public
	Sessions PondCoos	No recent samples	No recent samples	No recent samples	No recent samples	30 ft	Not recorded
	South PondsCoos	No recent samples	No recent samples	No recent samples	No recent samples	80 ft	✓ Public
	Success PondCoos	No recent samples	No recent samples	No recent samples	No recent samples	25 ft	✓ Public
	Sweat MeadowsCoos	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Third Connecticut LakeCoos	No recent samples	No recent samples	No recent samples	No recent samples	100 ft	Not recorded
	Trio PondsCoos	No recent samples	No recent samples	No recent samples	No recent samples	30 ft	Not recorded
	Umbagog LakeCoos	No recent samples	No recent samples	No recent samples	No recent samples	40 ft	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 New Hampshire Department of Environmental Services. See data sources.