Penacook Lake
Merrimack County, New Hampshire362 acresView mapDirections
No nutrient or algae sampling on record from NHDES for this lake.
- Impaired · Mercury
- 64 ft max depth
Penacook Lake in Merrimack County, New Hampshire has water-quality measurements published by NHDES, shown here as reported. Maximum depth: 64 ft. Surface area: 362 acres.
Penacook Lake is a 362-acre lake in Merrimack County, New Hampshire with a maximum depth of 64 feet (23-foot average).
Source: EPA Water Quality Portal sampling records, your state environmental agency. Methodology: how these readings are compared.
What Penacook Lake is good for
From access and monitoring records, not editorial picks.
- Deep water64 ft surveyed max depth
Swimming conditions
No readingNot rated
Nutrient and algae readings are not a swimming clearance. Penacook Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
Whether Penacook Lake is safe to swim in today is a call for the New Hampshire Department of Environmental Services and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Penacook Lake
These are the measurements NHDES publishes for Penacook Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
No clarity data. TSI undefined.
Ask about Penacook Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
64 ft
Average depth
22.6 ft
Surface area
362 acres
Shoreline
6.3 mi
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Stays near Penacook Lake
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Fishing Penacook Lake
EPA Impairment Status
Penacook Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
Designated uses not supporting: Fish consumption.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit NHLAK700060302-09 · Official waterbody report
Nearby Lakes in Merrimack County
Frequently asked questions about Penacook Lake
Where is Penacook Lake?
- Penacook Lake is a lake in Merrimack County, New Hampshire. Its water-quality measurements are published by NHDES and shown on this page as reported.
What is the water quality of Penacook Lake?
- Penacook Lake in Merrimack County, New Hampshire has water-quality measurements published by NHDES, shown here as reported. Maximum depth: 64 ft. Surface area: 362 acres.
Is Penacook Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Penacook Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
How deep is Penacook Lake?
- Penacook Lake has a maximum depth of 64 feet and an average depth of 22.6 feet. The lake covers 362 acres.
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Where this data comes from
Measurements for Penacook Lake come from the EPA Water Quality Portal. Per-sample source details are not recorded for this lake.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database