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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

3.1 -  13.92 mg/L   Mean: 7.44
(3274 readings)

Download physical data


43.3 -  81 deg F   Mean: 63
(3322 readings)


0.1 -  33.46 PSU   Mean: 26.9
(3248 readings)


6.63 -  8.93   Mean: 7.76
(3030 readings)

secchi disk2.jpg

Secchi Disk Depth

0.2 -  3.8 m   Mean: 1.46
(1437 measurements)

Download clarity data

TSS 1.2 -  48 mg/L   Mean: 7.11
(466 samples)


Nutrient Chemistry

PO4: 0.05 -  2.12 umol/L   Mean: 0.74 (425 samples)

Download nutrients data

Chlorophyll & Phaeophytin

Chl a: 0.4 -  41.1 umol/l   Mean: 4.57 (429 samples)



0 -  59400 count/100 mL  Geo. mean: 4 (2101 readings)

Download bacteria data

E. coli

0 -  99000 count/100 mL  Geo. mean: 15 (1124 samples)

Fecal coliform

0 -  312000 count/100 mL  Geo. mean: 28 (1154 samples)


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