Cambridge Reservoir
Middlesex County, Massachusetts546 acresView mapDirections
MassDEP publishes the water-quality measurements for Cambridge Reservoir. Here is what has been measured.
- Eutrophic
- Impaired · Salinity / chlorides
- 52 ft max depth
- Limited data
Cambridge Reservoir in Middlesex County, Massachusetts has water-quality measurements published by MassDEP, shown here as reported. Chlorophyll-a (algae): 7.4 µg/L. Surface area: 546 acres.
Cambridge Reservoir is a 546-acre productive, nutrient-rich eutrophic lake in Middlesex County, Massachusetts with an estimated average depth of about 52 feet. Compared to the 10 other monitored lakes in Middlesex County, Cambridge Reservoir ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, MassDEP, last sampled 2017-09-28. Methodology: how these readings are compared.
Cambridge Reservoir covers about 550 acres in Middlesex County. Vrbo is where to look for cabins and lake homes around Cambridge Reservoir, and Booking.com and Expedia search hotels near the lake for your dates.
Swimming conditions
Readings onlyLimited data
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. Cambridge Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for salinity / chlorides. Check local advisories before you swim.
Whether Cambridge Reservoir is safe to swim in today is a call for the Massachusetts Department of Environmental Protection and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Cambridge Reservoir
These are the measurements MassDEP publishes for Cambridge Reservoir, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
No clarity data. Chlorophyll-a 7.4 µg/L. TSI 50.
| 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 | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | 7.4µg/L | Fair GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 50 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Cambridge Reservoir
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
~52 ft est.
Surface area
546 acres
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Massachusetts has not published bathymetry for Cambridge Reservoir.
Lake Size & Watershed
Watershed (drainage) area
7 sq mi
HydroLAKES / HydroSHEDS
Shoreline
9.8 mi
HydroLAKES / HydroSHEDS
Elevation
171 ft
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.
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Stays near Cambridge Reservoir
Compare lakeside cabins, hotels, and vacation rentals near Cambridge Reservoir in Middlesex County, Massachusetts — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
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Fishing Cambridge Reservoir
Reservoir Info (USACE NID)
Cambridge Reservoir is a man-made reservoir impounded by the Cambridge Reservoir Dam (completed 1897), built primarily for water supply on the Hobbs Brook; earth-type dam, 31 ft tall and 1,450 ft long.
- Surface area
- 546 ac
- Normal storage
- 7,360 ac-ft
- Max storage
- 10,380 ac-ft
- Drainage area
- 6.7 sq mi
- Hazard class
- High
- Owner
- City of Cambridge
Source: USACE National Inventory of Dams, NID ID MA00750 · Operator website
EPA Impairment Status
Cambridge Reservoir is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Aquatic life.
Source: EPA ATTAINS assessment unit MA72014 · Official waterbody report
Nearby Lakes in Middlesex County
Frequently asked questions about Cambridge Reservoir
Where is Cambridge Reservoir?
- Cambridge Reservoir is a lake in Middlesex County, Massachusetts. Its water-quality measurements are published by MassDEP and shown on this page as reported.
What is the water quality of Cambridge Reservoir?
- Cambridge Reservoir in Middlesex County, Massachusetts has water-quality measurements published by MassDEP, shown here as reported. Chlorophyll-a (algae): 7.4 µg/L. Surface area: 546 acres.
Is Cambridge Reservoir safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Cambridge Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for salinity / chlorides. Check local advisories before you swim.
How deep is Cambridge Reservoir?
- No published bathymetric survey covers Cambridge Reservoir, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 52 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 546 acres.
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Where this data comes from
3 measurements from 1 monitoring station, 2017. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Massachusetts Department of Environmental Protection (MassDEP)
MASSDEP3 samples · 2017
Analytical methods
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
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.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)