Lake Winnepocket-Pratt Cove
Lake Winnepocket-Pratt Cove in Merrimack County, New Hampshire has a water quality grade of B (Good). Phosphorus: 5.6 µg/L. Surface area: 1 acres.
- Area
- 1 acres
- Type
- Oligotrophic
Lake Winnepocket-Pratt Cove is a 1-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, Lake Winnepocket-Pratt Cove ranks #18 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2024-06-12. 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: 5.6 µg/L. Trophic State Index: 29.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 5.6 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 29 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Lake Winnepocket-Pratt Cove
Compare lakeside cabins, hotels, and vacation rentals near Lake Winnepocket-Pratt 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.
Top-rated places to stay near Lake Winnepocket-Pratt Cove
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Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 1 acres |
No bathymetric survey has been published for Lake Winnepocket-Pratt Cove, so its depth is not documented here.
Fishing Lake Winnepocket-Pratt Cove
Reservoir Info (USACE NID)
Lake Winnepocket-Pratt Cove is a man-made reservoir impounded by the Blackwater Dam - Dodge Estate Dike (completed 1941), built primarily for flood risk reduction on the Blackwater River; gravity-type dam, 18 ft tall and 400 ft long.
- Surface area
- 1 ac
- Normal storage
- 0 ac-ft
- Max storage
- 93,400 ac-ft
- Drainage area
- 128 sq mi
- Hazard class
- High
- Owner
- USACE - New England District
Source: USACE National Inventory of Dams, NID ID NH03847 · Operator website · Matched by proximity (0.44 km)
EPA Impairment Status
Lake Winnepocket-Pratt Cove is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit NHLAK700030304-08 · Official waterbody report · Matched by proximity (0.56 km)
County Ranking
Ranked #18 of 41 lakes in Merrimack County
Nearby Lakes in Merrimack County
Frequently asked questions about Lake Winnepocket-Pratt Cove
Where is Lake Winnepocket-Pratt Cove?
- Lake Winnepocket-Pratt 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 Lake Winnepocket-Pratt Cove?
- Lake Winnepocket-Pratt Cove in Merrimack County, New Hampshire has a water quality grade of B (Good). Phosphorus: 5.6 µg/L. Surface area: 1 acres.
Is Lake Winnepocket-Pratt Cove safe to swim in?
- Good for swimming, clear water with low algae levels. Lake Winnepocket-Pratt Cove has a water quality grade of B (Good). Always check local health department advisories before swimming.
Explore Lake Winnepocket-Pratt Cove across LakeGrade
More New Hampshire Lake Rankings
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Grade A/B + low algae filter
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Other Grade B Lakes in New Hampshire
Hillsborough County · Good
Hillsborough County · Good
Hillsborough County · Good
Hillsborough County · Good
Belknap County · Good
Hillsborough County · Good
Oligotrophic Lakes in New Hampshire
Where this data comes from
5 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)
111133005 samples · 2022–2024
Analytical methods
- 10-115-01-1 F ~ LACHAT; Total Phosphorus- Manual persulfate digest
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