Deering Reservoir-Deep Spot
Deering Reservoir-Deep Spot in Hillsborough County, New Hampshire has a water quality grade of A (Excellent). Phosphorus: 9.6 µg/L. Chlorophyll-a (algae): 3 µg/L. Surface area: 323 acres.
- Area
- 323 acres
- Type
- Mesotrophic
- Public access
- Yes
Deering Reservoir-Deep Spot is a 323-acre mesotrophic lake in Hillsborough County, New Hampshire. Water quality is graded A based on 2 sampling years through 2025. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 35 other monitored lakes in Hillsborough County, Deering Reservoir-Deep Spot ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2025-08-05. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyBacteria advisory
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.
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A (Excellent)
No clarity data. Phosphorus level: 9.6 µg/L. Chlorophyll-a: 3 µg/L. Trophic State Index: 39.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 9.6 µg/L | Good |
| Chlorophyll-a (Algae) | 3 µg/L | Good |
| Trophic State Index (TSI) | 39 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Deering Reservoir-Deep Spot
Compare lakeside cabins, hotels, and vacation rentals near Deering Reservoir-Deep Spot in Hillsborough 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 Deering Reservoir-Deep Spot
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Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 323 acres |
| Public Access | Yes |
No bathymetric survey has been published for Deering Reservoir-Deep Spot, so its depth is not documented here.
Recreation & Access
- Deering ReservoirPublic
Named access points from the USGS National Boat Ramps inventory, snapped within 5 km. More lakes with boat ramps
Fishing Deering Reservoir-Deep Spot
Reservoir Info (USACE NID)
Deering Reservoir-Deep Spot is a man-made reservoir impounded by the Deering Reservoir Dam (completed 1940), built primarily for recreation on the Piscataquog River; earth-type dam, 25 ft tall and 873 ft long.
- Surface area
- 323 ac
- Normal storage
- 2,730 ac-ft
- Max storage
- 3,143 ac-ft
- Drainage area
- 4.3 sq mi
- Hazard class
- High
- Owner
- NH DES WATER DIVISION
Source: USACE National Inventory of Dams, NID ID NH00282 · Operator website · Matched by proximity (0.6 km)
EPA Impairment Status
Deering Reservoir-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
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit NHLAK700060601-01-02 · Official waterbody report · Matched by proximity (0.54 km)
County Ranking
Ranked #4 of 36 lakes in Hillsborough County
Nearby Lakes in Hillsborough County
Frequently asked questions about Deering Reservoir-Deep Spot
Where is Deering Reservoir-Deep Spot?
- Deering Reservoir-Deep Spot is a lake in Hillsborough County, New Hampshire. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Deering Reservoir-Deep Spot?
- Deering Reservoir-Deep Spot in Hillsborough County, New Hampshire has a water quality grade of A (Excellent). Phosphorus: 9.6 µg/L. Chlorophyll-a (algae): 3 µg/L. Surface area: 323 acres.
Is Deering Reservoir-Deep Spot safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Deering Reservoir-Deep Spot has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 3 µg/L. Always check local health department advisories before swimming.
Are there boat ramps on Deering Reservoir-Deep Spot?
- Deering Reservoir-Deep Spot has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Deering Reservoir. Public access is listed as yes.
Explore Deering Reservoir-Deep Spot 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 A Lakes in New Hampshire
Merrimack County · Excellent
Merrimack County · Excellent
Merrimack County · Excellent
Cheshire County · Excellent
Cheshire County · Excellent
Sullivan County · Excellent
Mesotrophic Lakes in New Hampshire
Where this data comes from
65 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)
1111330065 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)
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
Named boat-access points from the USGS National Boat Ramps inventory