Blaisdell Lake-Deep Spot
Merrimack County, New Hampshire161 acresView mapDirections
NHDES publishes the water-quality measurements for Blaisdell Lake-Deep Spot. Here is what has been measured.
- Mesotrophic
- Impaired · Mercury
- Public access
Blaisdell Lake-Deep Spot in Merrimack County, New Hampshire has water-quality measurements published by NHDES, shown here as reported. Phosphorus: 8.2 µg/L. Chlorophyll-a (algae): 2.8 µg/L. Surface area: 161 acres.
Blaisdell Lake-Deep Spot is a 161-acre mesotrophic lake in Merrimack County, New Hampshire. Limited fish-species data available. Public access is available. Compared to the 40 other monitored lakes in Merrimack County, Blaisdell Lake-Deep Spot ranks #8 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2025-08-07. Methodology: how these readings are compared.
Swimming conditions
Readings onlyLow algae
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Blaisdell Lake-Deep Spot is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury, pH / acidity. Check local advisories before you swim.
Whether Blaisdell Lake-Deep Spot 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 Blaisdell Lake-Deep Spot
These are the measurements NHDES publishes for Blaisdell Lake-Deep Spot, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
No clarity data. Phosphorus 8.2 µg/L. Chlorophyll-a 2.8 µg/L. TSI 38.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | No reading How deep a black-and-white disk stays visible from the surface. Higher is clearer. | |
| Total phosphorus | 8.2µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 2.8µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 38 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Blaisdell Lake-Deep Spot
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
161 acres
Public access
Yes
Listed by NHDES
No bathymetric survey has been published for Blaisdell Lake-Deep Spot, so its depth is not documented here.
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Fishing Blaisdell Lake-Deep Spot
Reservoir Info (USACE NID)
Blaisdell Lake-Deep Spot is a man-made reservoir impounded by the Blaisdell Lake Dam (completed 1916), built primarily for recreation on the Tr Warner River; concrete-type dam, 9 ft tall and 150 ft long.
- Surface area
- 161 ac
- Normal storage
- 425 ac-ft
- Max storage
- 600 ac-ft
- Drainage area
- 2.48 sq mi
- Hazard class
- Low
- Owner
- BLAISDELL LAKE PROTECTIVE ASSOC
Source: USACE National Inventory of Dams, NID ID NH00563 · Operator website · Matched by proximity (0.86 km)
EPA Impairment Status
Blaisdell Lake-Deep Spot 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: Aquatic life, Fish consumption.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit NHLAK700030302-02 · Official waterbody report
Nearby Lakes in Merrimack County
Frequently asked questions about Blaisdell Lake-Deep Spot
Where is Blaisdell Lake-Deep Spot?
- Blaisdell Lake-Deep Spot 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 Blaisdell Lake-Deep Spot?
- Blaisdell Lake-Deep Spot in Merrimack County, New Hampshire has water-quality measurements published by NHDES, shown here as reported. Phosphorus: 8.2 µg/L. Chlorophyll-a (algae): 2.8 µg/L. Surface area: 161 acres.
Is Blaisdell Lake-Deep Spot safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Blaisdell Lake-Deep Spot is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury, pH / acidity. Check local advisories before you swim.
Can I fish at Blaisdell Lake-Deep Spot?
- Public access to Blaisdell Lake-Deep Spot is listed as yes on the lake record. Seasons, size and bag limits, and whether you need a license are set by New Hampshire's fish and wildlife agency, so check its current regulations before you go.
Explore Blaisdell Lake-Deep Spot across LakeQuality
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Mesotrophic Lakes in New Hampshire
Where this data comes from
17 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- New Hampshire Department Of Environmental Services (BEACH)
1111330017 samples · 2020–2025
Analytical methods
- 10-115-01-1 F ~ LACHAT; Total Phosphorus- Manual persulfate digest
- CHLOROPHYLL A-B-C DETERMINATION (MODIFIED)
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database