Pleasant Lake-Southeast Cove
Pleasant Lake-Southeast Cove in Merrimack County, New Hampshire has a water quality grade of B (Good). Phosphorus: 5 µg/L. Surface area: 604 acres.
- Area
- 604 acres
- Type
- Oligotrophic
Pleasant Lake-Southeast Cove is a 604-acre cold, clear oligotrophic lake in Merrimack County, New Hampshire. Water quality is graded B based on 1 sampling years through 2024. Compared to the 40 other monitored lakes in Merrimack County, Pleasant Lake-Southeast Cove ranks #20 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2024-09-10. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLimited data
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Good for swimming, clear water with low algae levels
Water Quality Grade: B (Good)
No clarity data. Phosphorus level: 5 µg/L. Trophic State Index: 27.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 5 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 27 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Pleasant Lake-Southeast Cove
Compare lakeside cabins, hotels, and vacation rentals near Pleasant Lake-Southeast Cove in Merrimack County, New Hampshire — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
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Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 604 acres |
No bathymetric survey has been published for Pleasant Lake-Southeast Cove, so its depth is not documented here.
Fishing Pleasant Lake-Southeast Cove
Reservoir Info (USACE NID)
Pleasant Lake-Southeast Cove is a man-made reservoir impounded by the Pleasant Lake Dam (completed 1850), built primarily for recreation on the Tr Blackwater River; earth-type dam, 13 ft tall and 360 ft long.
- Surface area
- 604 ac
- Normal storage
- 6,806 ac-ft
- Max storage
- 9,295 ac-ft
- Drainage area
- 11.03 sq mi
- Hazard class
- High
- Owner
- TOWN OF NEW LONDON
Source: USACE National Inventory of Dams, NID ID NH00362 · Operator website · Matched by proximity (0.89 km)
EPA Impairment Status
Pleasant Lake-Southeast Cove is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit NHLAK700030402-02-01 · Official waterbody report · Matched by proximity (0.72 km)
County Ranking
Ranked #20 of 41 lakes in Merrimack County
Nearby Lakes in Merrimack County
Frequently asked questions about Pleasant Lake-Southeast Cove
Where is Pleasant Lake-Southeast Cove?
- Pleasant Lake-Southeast Cove is a lake in Merrimack County, New Hampshire. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Pleasant Lake-Southeast Cove?
- Pleasant Lake-Southeast Cove in Merrimack County, New Hampshire has a water quality grade of B (Good). Phosphorus: 5 µg/L. Surface area: 604 acres.
Is Pleasant Lake-Southeast Cove safe to swim in?
- Good for swimming, clear water with low algae levels. Pleasant Lake-Southeast Cove has a water quality grade of B (Good). Always check local health department advisories before swimming.
Explore Pleasant Lake-Southeast Cove across LakeGrade
More New Hampshire Lake Rankings
Top 25 by overall water quality score
Top 25 by Secchi water clarity
Grade A/B + low algae filter
Panfish-rich, public access
Full state directory
Other Grade B Lakes in New Hampshire
Oligotrophic Lakes in New Hampshire
Where this data comes from
10 measurements from 1 monitoring station, 2022–2024. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- New Hampshire Department Of Environmental Services (BEACH)
1111330010 samples · 2022–2024
Analytical methods
- 10-115-01-1 F ~ LACHAT; Total Phosphorus- Manual persulfate digest
- Phosphorus by Two Reagent Colorimetry
- 2130 B ~ Nephelometric Method
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database