MWRA online - home
Water System
Sewer System
Harbor and Bay
School Program
About MWRA
Doing Business with MWRA
Contact MWRA


Boston Harbor and Massachusetts Bay
MWRA Environmental Quality Department

The Neponset River

Boston Harbor Page Harbor Beaches Page Charles River Page Mystic River Page Neponset River Page
Boston Harbor Beaches Charles River Mystic River Neponset River


The Neponset River often fails to meet state bacterial water quality standards, except at the river mouth, where river water mixes with cleaner harbor water. Water quality does not consistently meet standards near Tenean Beach or the Commercial Point combined sewer overflow treatment facility outfall.

MWRA's Environmental Quality Department manages water quality data on bacteria, algae, water clarity, dissolved oxygen, nutrients, and suspended solids in Boston Harbor and its tributary rivers.

Neponset River  sampling map
See larger map with sampling locations

See all Harbor & river sampling locations

Water Quality Parameter

Historic Range for the Neponset*


Dissolved Oxygen

3.79-13.92 mg/L   Mean: 7.68
(2284 readings)

Download physical data


44.9-81.1 deg F   Mean: 63.8
(2293 readings)


0.12-33.46 PSU   Mean: 27.29
(2231 readings)


6.68- 8.09   Mean: 7.76
(2160 readings)

secchi disk2.jpg

Secchi Disk Depth

0.2-2.6 m   Mean: 1.31
(1012 measurements)

Download clarity data

TSS 0.71- 69.6 mg/L   Mean: 9.25
(262 samples)


Nutrient Chemistry

PO4: 0.05- 1.69 umol/L   Mean: 0.68
(226 samples)

Download nutrients data

Chlorophyll & Phaeophytin

Chl a: 0.74-41.7 umol/l   Mean: 4.89
(227 samples)



0- 59400 count/100 mL  Geo. mean: 5 (1397 readings)

Download bacteria data

E. coli

52-10500 count/100 mL  Geo. mean: 203 (84 samples)

Fecal coliform

0-234000 count/100 mL  Geo. mean: 27 (1452 samples)


Questions or comments? Email us