Crystal Lake-Outlet
Belknap County, New Hampshire1,155 acresView mapDirections
NHDES publishes the water-quality measurements for Crystal Lake-Outlet. Here is what has been measured.
- Oligotrophic
- Public access
Crystal Lake-Outlet in Belknap County, New Hampshire has water-quality measurements published by NHDES, shown here as reported. Phosphorus: 11.6 µg/L. Surface area: 1155 acres.
Crystal Lake-Outlet is a 1,155-acre cold, clear oligotrophic lake in Belknap County, New Hampshire. Limited fish-species data available. Public access is available. Compared to the 26 other monitored lakes in Belknap County, Crystal Lake-Outlet ranks #12 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2025-08-25. Methodology: how these readings are compared.
What Crystal Lake-Outlet is good for
From access and monitoring records, not editorial picks.
- Big water1,155 acres
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. Check local advisories before you swim.
Whether Crystal Lake-Outlet 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 Crystal Lake-Outlet
These are the measurements NHDES publishes for Crystal Lake-Outlet, 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 11.6 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 | 11.6µg/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 Crystal Lake-Outlet
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
1,155 acres
Public access
Yes
Listed by NHDES
No bathymetric survey has been published for Crystal Lake-Outlet, so its depth is not documented here.
Stays via Stay22
Stays near Crystal Lake-Outlet
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Top-rated places to stay near Crystal Lake-Outlet
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Fishing Crystal Lake-Outlet
Reservoir Info (USACE NID)
Crystal Lake-Outlet is a man-made reservoir impounded by the Crystal Lake Dam (completed 1881), built primarily for recreation on the Mascoma River; concrete-type dam, 18 ft tall and 575 ft long.
- Surface area
- 1,155 ac
- Normal storage
- 8,332 ac-ft
- Max storage
- 18,300 ac-ft
- Drainage area
- 153 sq mi
- Hazard class
- High
- Owner
- NH DES WATER DIVISION
Source: USACE National Inventory of Dams, NID ID NH00018 · Operator website · Matched by proximity (0.03 km)
Nearby Lakes in Belknap County
Frequently asked questions about Crystal Lake-Outlet
Where is Crystal Lake-Outlet?
- Crystal Lake-Outlet is a lake in Belknap County, New Hampshire. Its water-quality measurements are published by NHDES and shown on this page as reported.
What is the water quality of Crystal Lake-Outlet?
- Crystal Lake-Outlet in Belknap County, New Hampshire has water-quality measurements published by NHDES, shown here as reported. Phosphorus: 11.6 µg/L. Surface area: 1155 acres.
Is Crystal Lake-Outlet safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Can I fish at Crystal Lake-Outlet?
- Public access to Crystal Lake-Outlet 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.
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Where this data comes from
17 measurements from 1 monitoring station, 2021–2025. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- New Hampshire Department Of Environmental Services (BEACH)
1111330017 samples · 2021–2025
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.