Highland Lake-Outlet
Merrimack County, New Hampshire210 acresView mapDirections
NHDES publishes the water-quality measurements for Highland Lake-Outlet. Here is what has been measured.
- Mesotrophic
Highland Lake-Outlet in Merrimack County, New Hampshire has water-quality measurements published by NHDES, shown here as reported. Phosphorus: 16.6 µg/L. Surface area: 210 acres.
Highland Lake-Outlet is a 210-acre mesotrophic lake in Merrimack County, New Hampshire. Compared to the 40 other monitored lakes in Merrimack County, Highland Lake-Outlet ranks #32 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2025-09-18. 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. Check local advisories before you swim.
Whether Highland 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 Highland Lake-Outlet
These are the measurements NHDES publishes for Highland 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 16.6 µg/L. TSI 45.
| 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 | 16.6µg/L | Fair 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. | 45 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Highland Lake-Outlet
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
210 acres
No bathymetric survey has been published for Highland Lake-Outlet, so its depth is not documented here.
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Fishing Highland Lake-Outlet
Reservoir Info (USACE NID)
Highland Lake-Outlet is a man-made reservoir impounded by the Highland Lake Dam (completed 1935), built primarily for recreation on the Tr Sucker Brook; earth-type dam, 10 ft tall and 180 ft long.
- Surface area
- 210 ac
- Normal storage
- 440 ac-ft
- Max storage
- 1,050 ac-ft
- Drainage area
- 5.02 sq mi
- Hazard class
- Significant
- Owner
- TOWN OF ANDOVER
Source: USACE National Inventory of Dams, NID ID NH00035 · Operator website · Matched by proximity (0.01 km)
Nearby Lakes in Merrimack County
Frequently asked questions about Highland Lake-Outlet
Where is Highland Lake-Outlet?
- Highland Lake-Outlet 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 Highland Lake-Outlet?
- Highland Lake-Outlet in Merrimack County, New Hampshire has water-quality measurements published by NHDES, shown here as reported. Phosphorus: 16.6 µg/L. Surface area: 210 acres.
Is Highland Lake-Outlet safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Explore Highland Lake-Outlet across LakeQuality
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Where this data comes from
13 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)
1111330013 samples · 2020–2025
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.