Long Pond
Barnstable County, Massachusetts53 acresView mapDirections
Not enough samples to grade — no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). No letter yet. Here is what we do have.
- Impaired · Impaired biota (cause unknown)
- 38 ft max depth
- Public access
- Limited data
Long Pond in Barnstable County, Massachusetts is not rated for water quality — its monitoring record does not meet the evidence bar. Chlorophyll-a (algae): 5 µg/L. Surface area: 53 acres.
- Max depth
- ~38 ft est.
- Area
- 53 acres
- Chlorophyll-a
- 5 µg/L
- Public access
- Yes
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Watch Long Pond’s letter
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Why Long Pond has no grade
We grade a lake only when the monitoring record supports a letter: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Long Pond, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). Sampling here has recorded algae (chlorophyll-a), but not water clarity and phosphorus.
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by MassDEP and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Long Pond is a 53-acre lake in Barnstable County, Massachusetts with an estimated average depth of about 38 feet. Limited fish-species data available. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, MassDEP, last sampled 2018-08-08. Grade methodology: LakeQuality methodology.
What Long Pond is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Swimming Safety
Not ratedBacteria advisory
The letter is not a swimming clearance. Long Pond is listed impaired under Clean Water Act §303(d) (IR 4A) for impaired biota (cause unknown), nutrients (phosphorus, nitrogen), pathogens (E. coli, fecal). Check local advisories before you swim.
Water quality measurements for Long Pond
These readings exist but are not enough for an A–F grade — see why.
No clarity data. Chlorophyll-a 5 µg/L. TSI 46.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | 5 µg/L | Not graded |
| Trophic State Index (TSI) | 46 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~38 ft est. |
| Average Depth | ~8 ft est. |
| Surface Area | 53 acres |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Massachusetts has not published bathymetry for Long Pond.
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
- Long PondPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Long Pond
Reservoir Info (USACE NID)
Long Pond is a man-made reservoir impounded by the Long Pond Dam (completed 1966), built primarily for recreation on the Tributary to Parkers River; earth-type dam, 7 ft tall and 95 ft long.
- Surface area
- 53 ac
- Normal storage
- 80 ac-ft
- Max storage
- 330 ac-ft
- Drainage area
- 1.9 sq mi
- Hazard class
- Low
- Owner
- Town of Yarmouth
Source: USACE National Inventory of Dams, NID ID MA02494 · Operator website
EPA Impairment Status
Long Pond 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 MA96-12 · Official waterbody report · Matched by proximity (1.25 km)
Graded lakes near Long Pond
Long Pond has no grade, but these lakes within a short drive do.
Nearby Lakes in Barnstable County
Frequently asked questions about Long Pond
Where is Long Pond?
- Long Pond is a lake in Barnstable County, Massachusetts. LakeQuality has not rated this lake (UNRATED) — no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years).
What is the water quality grade for Long Pond?
- Long Pond in Barnstable County, Massachusetts is not rated for water quality — its monitoring record does not meet the evidence bar. Chlorophyll-a (algae): 5 µg/L. Surface area: 53 acres.
Is Long Pond safe to swim in?
- The letter is not a swimming clearance. Long Pond is listed impaired under Clean Water Act §303(d) (IR 4A) for impaired biota (cause unknown), nutrients (phosphorus, nitrogen), pathogens (E. coli, fecal). Check local advisories before you swim.
How deep is Long Pond?
- No published bathymetric survey covers Long Pond, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 38 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 53 acres.
Are there boat ramps on Long Pond?
- Long Pond has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Long Pond. Public access is listed as yes.
Explore Long Pond across LakeQuality
Planning a trip around Cape Cod?
Long Pond is about 19 miles from Cape Cod National Seashore. Crowds there swing hard by season, so the month you pick changes both how busy the park is and what lodging costs.
Best time to visit Cape Cod →More Massachusetts Lake Rankings
Other Lakes in Massachusetts
Mesotrophic Lakes in Massachusetts
Where this data comes from
2 measurements from 1 monitoring station, 2018. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Massachusetts Department of Environmental Protection (MassDEP)
MASSDEP2 samples · 2018
Analytical methods
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
Monitoring station identifiers (1)
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