Lake Dunmore
Addison County, Vermont985 acresView mapDirections
Clarity, phosphorus, and algae all sit in the cleanest band for this region.
- Mesotrophic
- Impaired · Hydrologic alteration
- #1 of 5 in the county
- 57 ft max depth
- Public access
Lake Dunmore in Addison County, Vermont has a water quality grade of A (Excellent). Water clarity: 16.4 ft visibility. Phosphorus: 10.9 µg/L. Chlorophyll-a (algae): 2.9 µg/L. Surface area: 985 acres.
- Clarity
- 16.4 ft
- Max depth
- ~57 ft est.
- Area
- 985 acres
- Type
- Mesotrophic
- Phosphorus
- 10.9 µg/L
- Chlorophyll-a
- 2.9 µg/L
- Trend
- ↑ Improving
- Public access
- Yes
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Watch Lake Dunmore’s letter
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Lake Dunmore is a 985-acre mesotrophic lake in Addison County, Vermont with an estimated average depth of about 57 feet. Water quality is graded A based on 2 sampling years through 2025. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 4 other monitored lakes in Addison County, Lake Dunmore ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, VT DEC, last sampled 2025-08-13. Grade methodology: LakeQuality methodology.
What Lake Dunmore is good for
From access and monitoring records, not editorial picks.
- Clear water16.4 ft of visibility
- Boat launch1 documented ramp
Swimming Safety
Grade onlyLow algae
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.
The A is nutrients and algae, not a swimming clearance. Lake Dunmore is listed impaired under Clean Water Act §303(d) (IR 4C) for hydrologic alteration. Check local advisories before you swim.
Water Quality Grade: A (Excellent)
Crystal clear, you can see 16.4 ft down. Phosphorus 10.9 µg/L. Chlorophyll-a 2.9 µg/L. TSI 39. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 16.4 ft | Not graded |
| Phosphorus | 10.9 µg/L | Good |
| Chlorophyll-a (Algae) | 2.9 µg/L | Good |
| Trophic State Index (TSI) | 39 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~57 ft est. |
| Average Depth | ~48 ft est. |
| Surface Area | 985 acres |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Vermont has not published bathymetry for Lake Dunmore.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Recreation & Access
- MagoonPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Lake Dunmore
Water Quality Trend: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.064 m/yr | 6 |
| Phosphorus | ↑ Improving | -1.03 µg/L/yr | 6 |
| Chlorophyll-a | ↑ Improving | -0.71 µg/L/yr | 6 |
Reservoir Info (USACE NID)
Lake Dunmore is a man-made reservoir impounded by the Lake Dunmore (completed 1920), built primarily for hydroelectric on the Leicester River; earth-type dam, 8 ft tall and 70 ft long.
- Surface area
- 985 ac
- Normal storage
- 0 ac-ft
- Max storage
- 4,900 ac-ft
- Drainage area
- 20.42 sq mi
- Hazard class
- Low
- Owner
- GREEN MOUNTAIN POWER CORP
Source: USACE National Inventory of Dams, NID ID VT00191 · Operator website
EPA Impairment Status
Lake Dunmore is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 4C).
Causes of impairment
Source: EPA ATTAINS assessment unit VT03-04L05_01 · Official waterbody report
County Ranking
Ranked #1 of 5 lakes in Addison County
Nearby Lakes in Addison County
Frequently asked questions about Lake Dunmore
Where is Lake Dunmore?
- Lake Dunmore is a lake in Addison County, Vermont. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Lake Dunmore?
- Lake Dunmore in Addison County, Vermont has a water quality grade of A (Excellent). Water clarity: 16.4 ft visibility. Phosphorus: 10.9 µg/L. Chlorophyll-a (algae): 2.9 µg/L. Surface area: 985 acres.
Is Lake Dunmore safe to swim in?
- The A is nutrients and algae, not a swimming clearance. Lake Dunmore is listed impaired under Clean Water Act §303(d) (IR 4C) for hydrologic alteration. Check local advisories before you swim.
How deep is Lake Dunmore?
- No published bathymetric survey covers Lake Dunmore, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 57 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 985 acres.
Are there boat ramps on Lake Dunmore?
- Lake Dunmore has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Magoon. Public access is listed as yes.
Explore Lake Dunmore across LakeQuality
2 documented falls within 11 mi, nearest Texas Falls
Species activity outlook by water temperature and season
Where to stay at Vermont's top lakes, each with its grade
Moderate nutrients, good water quality
Vermont's cleanest and most-polluted lakes, ranked
More Vermont Lake Rankings
Other Grade A Lakes in Vermont
Mesotrophic Lakes in Vermont
Where this data comes from
271 measurements from 2 monitoring stations, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Vermont Dept of Environmental Conservation
1VTDECWQ271 samples · 2020–2025
Analytical methods
- EPA approved Alternate Test Procedure for 4500 P H. Has a 28 day hold without acid preservation.
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
Monitoring station identifiers (2)
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory