Silver Lake-Deep Spot
Hillsborough County, New Hampshire34 acresView mapDirections
NHDES publishes the water-quality measurements for Silver Lake-Deep Spot. Here is what has been measured.
- Oligotrophic
- Impaired · Algal growth
- Public access
Silver Lake-Deep Spot in Hillsborough County, New Hampshire has water-quality measurements published by NHDES, shown here as reported. Phosphorus: 11.4 µg/L. Surface area: 34 acres.
Silver Lake-Deep Spot is a 34-acre cold, clear oligotrophic lake in Hillsborough County, New Hampshire. Limited fish-species data available. Public access is available. Compared to the 35 other monitored lakes in Hillsborough County, Silver Lake-Deep Spot ranks #5 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2025-08-03. Methodology: how these readings are compared.
Swimming conditions
Readings onlyBacteria advisory
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. Silver Lake-Deep Spot is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, biotoxins, mercury, nutrients (phosphorus, nitrogen), pH / acidity. Check local advisories before you swim.
Whether Silver 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 Silver Lake-Deep Spot
These are the measurements NHDES publishes for Silver 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 11.4 µg/L. TSI 39.
| 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 | 11.4µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 39 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Silver Lake-Deep Spot
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
34 acres
Public access
Yes
Listed by NHDES
No bathymetric survey has been published for Silver Lake-Deep Spot, so its depth is not documented here.
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Fishing Silver Lake-Deep Spot
Reservoir Info (USACE NID)
Silver Lake-Deep Spot is a man-made reservoir impounded by the Silver Lake Dam (completed 1930), built primarily for recreation on the Pennichuck Brook; earth-type dam, 8 ft tall and 16.6 ft long.
- Surface area
- 34 ac
- Normal storage
- 90 ac-ft
- Max storage
- 120 ac-ft
- Drainage area
- 0.34 sq mi
- Hazard class
- Low
- Owner
- NH DNCR
Source: USACE National Inventory of Dams, NID ID NH01056 · Operator website · Matched by proximity (0.34 km)
EPA Impairment Status
Silver Lake-Deep Spot is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Aquatic life, Fish consumption, Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit NHLAK700061001-02-01 · Official waterbody report
Nearby Lakes in Hillsborough County
Frequently asked questions about Silver Lake-Deep Spot
Where is Silver Lake-Deep Spot?
- Silver Lake-Deep Spot is a lake in Hillsborough County, New Hampshire. Its water-quality measurements are published by NHDES and shown on this page as reported.
What is the water quality of Silver Lake-Deep Spot?
- Silver Lake-Deep Spot in Hillsborough County, New Hampshire has water-quality measurements published by NHDES, shown here as reported. Phosphorus: 11.4 µg/L. Surface area: 34 acres.
Is Silver Lake-Deep Spot safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Silver Lake-Deep Spot is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, biotoxins, mercury, nutrients (phosphorus, nitrogen), pH / acidity. Check local advisories before you swim.
Can I fish at Silver Lake-Deep Spot?
- Public access to Silver 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 Silver Lake-Deep Spot across LakeQuality
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Where this data comes from
21 measurements from 1 monitoring station, 2022–2025. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- New Hampshire Department Of Environmental Services (BEACH)
1111330021 samples · 2022–2025
Analytical methods
- 10-115-01-1 F ~ LACHAT; Total Phosphorus- Manual persulfate digest
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