Lake Memphremagog
Orleans County, VermontView mapDirections
Nutrients and algae sit mid-range for this region.
↓ down from B at the last regrade
- Mesotrophic
- Impaired · Hydrologic alteration
- #14 of 17 in the county
- 292 ft max depth
- Public access
Lake Memphremagog in Orleans County, Vermont has a water quality grade of C (Fair). Water clarity: 10.5 ft visibility. Phosphorus: 16.4 µg/L. Chlorophyll-a (algae): 5.5 µg/L.
- Clarity
- 10.5 ft
- Max depth
- ~292 ft est.
- Type
- Mesotrophic
- Phosphorus
- 16.4 µg/L
- Chlorophyll-a
- 5.5 µg/L
- Trend
- → Stable
- Public access
- Yes
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Watch Lake Memphremagog’s letter
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Lake Memphremagog is a mesotrophic lake in Orleans County, Vermont with an estimated average depth of about 292 feet. Water quality is graded C based on 2 sampling years through 2025. Water clarity is declining over recent sampling years. Limited fish-species data available. Public access is available with 2 public boat landings. Compared to the 16 other monitored lakes in Orleans County, Lake Memphremagog ranks #14 for water quality.
Source: EPA Water Quality Portal sampling records, VT DEC, last sampled 2025-08-19. Grade methodology: LakeQuality methodology.
What Lake Memphremagog is good for
From access and monitoring records, not editorial picks.
- Clear water10.5 ft of visibility
- Boat launch2 documented ramps
Swimming Safety
Grade onlyModerate
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 C is nutrients and algae, not a swimming clearance. Lake Memphremagog is listed impaired under Clean Water Act §303(d) (IR 4A) for hydrologic alteration, nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Water Quality Grade: C (Fair)
Good clarity, visible to about 10.5 ft. Phosphorus 16.4 µg/L. Chlorophyll-a 5.5 µg/L. TSI 45. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10.5 ft | Not graded |
| Phosphorus | 16.4 µg/L | Fair |
| Chlorophyll-a (Algae) | 5.5 µg/L | Fair |
| Trophic State Index (TSI) | 45 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~292 ft est. |
| Average Depth | ~121 ft est. |
| 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 Memphremagog.
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
- Johns RiverPublic
- Whipple PointPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Lake Memphremagog
Water Quality Trend: → Stable
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.219 m/yr | 6 |
| Phosphorus | → Stable | -0.12 µg/L/yr | 6 |
| Chlorophyll-a | ↑ Improving | -0.43 µg/L/yr | 6 |
EPA Impairment Status
Lake Memphremagog is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit VT17-01L01_01 · Official waterbody report
County Ranking
Ranked #14 of 17 lakes in Orleans County
Nearby Lakes With Higher Grades
Lake Memphremagog holds Grade C. 2 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Orleans County
Frequently asked questions about Lake Memphremagog
Where is Lake Memphremagog?
- Lake Memphremagog is a lake in Orleans County, Vermont. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Lake Memphremagog?
- Lake Memphremagog in Orleans County, Vermont has a water quality grade of C (Fair). Water clarity: 10.5 ft visibility. Phosphorus: 16.4 µg/L. Chlorophyll-a (algae): 5.5 µg/L.
Is Lake Memphremagog safe to swim in?
- The C is nutrients and algae, not a swimming clearance. Lake Memphremagog is listed impaired under Clean Water Act §303(d) (IR 4A) for hydrologic alteration, nutrients (phosphorus, nitrogen). Check local advisories before you swim.
How deep is Lake Memphremagog?
- No published bathymetric survey covers Lake Memphremagog, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 292 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Are there boat ramps on Lake Memphremagog?
- Lake Memphremagog has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Johns River, Whipple Point. Public access is listed as yes.
Explore Lake Memphremagog across LakeQuality
Depth, room, public access, and the state wake-sport rules
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
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Other Grade C Lakes in Vermont
Mesotrophic Lakes in Vermont
Where this data comes from
503 measurements from 4 monitoring stations, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Vermont Dept of Environmental Conservation
1VTDECWQ503 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 (4)
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