Caspian Lake
Orleans County, Vermont789 acresView mapDirections
Clarity, phosphorus, and algae all sit in the cleanest band for this region.
- Oligotrophic
- #1 of 17 in the county
- 57 ft max depth
Caspian Lake in Orleans County, Vermont has a water quality grade of A (Excellent). Water clarity: 29.5 ft visibility. Phosphorus: 7.8 µg/L. Chlorophyll-a (algae): 1.3 µg/L. Surface area: 789 acres.
- Clarity
- 29.5 ft
- Max depth
- ~57 ft est.
- Area
- 789 acres
- Type
- Oligotrophic
- Phosphorus
- 7.8 µg/L
- Chlorophyll-a
- 1.3 µg/L
- Trend
- ↑ Improving
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Watch Caspian Lake’s letter
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Caspian Lake is a 789-acre cold, clear oligotrophic lake in Orleans 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. Compared to the 16 other monitored lakes in Orleans County, Caspian Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, VT DEC, last sampled 2025-08-11. Grade methodology: LakeQuality methodology.
What Caspian Lake is good for
From access and monitoring records, not editorial picks.
- Clear water29.5 ft of visibility
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. Check local advisories before you swim.
Water Quality Grade: A (Excellent)
Crystal clear, you can see 29.5 ft down. Phosphorus 7.8 µg/L. Chlorophyll-a 1.3 µg/L. TSI 32. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 29.5 ft | Not graded |
| Phosphorus | 7.8 µg/L | Good |
| Chlorophyll-a (Algae) | 1.3 µg/L | Good |
| Trophic State Index (TSI) | 32 | Oligotrophic |
Low nutrients, clear water. The letter is not a swimming clearance.
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~57 ft est. |
| Average Depth | ~24 ft est. |
| Surface Area | 789 acres |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Vermont has not published bathymetry for Caspian Lake.
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.
Fishing Caspian Lake
Water Quality Trend: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.143 m/yr | 6 |
| Phosphorus | ↑ Improving | -0.79 µg/L/yr | 6 |
| Chlorophyll-a | ↑ Improving | -0.41 µg/L/yr | 6 |
Reservoir Info (USACE NID)
Caspian Lake is a man-made reservoir impounded by the Caspian Lake (completed 1929), built primarily for hydroelectric on the Greensboro Brook; earth-type dam, 7 ft tall and 205 ft long.
- Surface area
- 789 ac
- Normal storage
- 0 ac-ft
- Max storage
- 4,300 ac-ft
- Drainage area
- 7.05 sq mi
- Hazard class
- Significant
- Owner
- HARDWICK ELECTRIC DEPARTMENT
All listed purposes: Hydroelectric;Recreation.
Source: USACE National Inventory of Dams, NID ID VT00183 · Operator website
County Ranking
Ranked #1 of 17 lakes in Orleans County
Nearby Lakes in Orleans County
Frequently asked questions about Caspian Lake
Where is Caspian Lake?
- Caspian Lake is a lake in Orleans County, Vermont. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Caspian Lake?
- Caspian Lake in Orleans County, Vermont has a water quality grade of A (Excellent). Water clarity: 29.5 ft visibility. Phosphorus: 7.8 µg/L. Chlorophyll-a (algae): 1.3 µg/L. Surface area: 789 acres.
Is Caspian Lake safe to swim in?
- The A is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
How deep is Caspian Lake?
- No published bathymetric survey covers Caspian Lake, 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 789 acres.
Explore Caspian Lake across LakeQuality
Species activity outlook by water temperature and season
Where to stay at Vermont's top lakes, each with its grade
Low nutrients, clear water. The letter is not a swimming clearance.
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Where this data comes from
298 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
1VTDECWQ298 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
- 2130 B ~ Nephelometric Method
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
Lake size & watershed from HydroLAKES (HydroSHEDS)