Warren Lake-Deep Spot
Cheshire County, New Hampshire200 acresView mapDirections
NHDES publishes the water-quality measurements for Warren Lake-Deep Spot. Here is what has been measured.
- Eutrophic
- Impaired · Algal growth
Warren Lake-Deep Spot in Cheshire County, New Hampshire has water-quality measurements published by NHDES, shown here as reported. Phosphorus: 16.8 µg/L. Chlorophyll-a (algae): 7.6 µg/L. Surface area: 200 acres.
Warren Lake-Deep Spot is a 200-acre productive, nutrient-rich eutrophic lake in Cheshire County, New Hampshire. Compared to the 37 other monitored lakes in Cheshire County, Warren Lake-Deep Spot ranks #29 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2025-09-02. Methodology: how these readings are compared.
Swimming conditions
Readings onlyModerate 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. Warren Lake-Deep Spot is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, mercury, nutrients (phosphorus, nitrogen), pH / acidity. Check local advisories before you swim.
Whether Warren 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 Warren Lake-Deep Spot
These are the measurements NHDES publishes for Warren 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 16.8 µg/L. Chlorophyll-a 7.6 µg/L. TSI 48.
| 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 | 16.8µg/L | Fair GoodFairPoor |
| Chlorophyll-a (algae) | 7.6µg/L | Fair GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 48 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Warren Lake-Deep Spot
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
200 acres
No bathymetric survey has been published for Warren Lake-Deep Spot, so its depth is not documented here.
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Stays near Warren Lake-Deep Spot
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Fishing Warren Lake-Deep Spot
Reservoir Info (USACE NID)
Warren Lake-Deep Spot is a man-made reservoir impounded by the Warren Lake Dam (completed 1771), built primarily for recreation on the Warren Brook; rockfill-type dam, 13 ft tall and 170 ft long.
- Surface area
- 200 ac
- Normal storage
- 501 ac-ft
- Max storage
- 1,739 ac-ft
- Drainage area
- 4.88 sq mi
- Hazard class
- High
- Owner
- TOWN OF ALSTEAD
Source: USACE National Inventory of Dams, NID ID NH00008 · Operator website · Matched by proximity (0.95 km)
EPA Impairment Status
Warren 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.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit NHLAK801070203-01 · Official waterbody report
Nearby Lakes in Cheshire County
Frequently asked questions about Warren Lake-Deep Spot
Where is Warren Lake-Deep Spot?
- Warren Lake-Deep Spot is a lake in Cheshire County, New Hampshire. Its water-quality measurements are published by NHDES and shown on this page as reported.
What is the water quality of Warren Lake-Deep Spot?
- Warren Lake-Deep Spot in Cheshire County, New Hampshire has water-quality measurements published by NHDES, shown here as reported. Phosphorus: 16.8 µg/L. Chlorophyll-a (algae): 7.6 µg/L. Surface area: 200 acres.
Is Warren Lake-Deep Spot safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Warren Lake-Deep Spot is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, mercury, nutrients (phosphorus, nitrogen), pH / acidity. Check local advisories before you swim.
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Where this data comes from
31 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)
1111330031 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