Summary
CRWA
conducted water quality monitoring on
Canterbury Brook on four occasions: 1) August 3, 2006 – a dry weather
monitoring event, 2) August 23, 2006 – a dry weather monitoring event, 3) November 8, 2006 – a wet weather monitoring event,
and 4) May 18, 2007 - a wet weather monitoring event.
Samples
were collected at seven sites along Canterbury Brook.
Click here for a site
map. Samples were analyzed for
several pollutants of most concern in the watershed: E. coli bacteria, total suspended solids, and total phosphorus. CRWA also measured several in
situ parameters including pH, dissolved oxygen, specific conductivity
and water temperature.
E.
coli levels in all locations except CANT6 during all four monitoring
events exceeded the Massachusetts Surface Water Quality Standard for
swimming, 126cfu/100mL,
and almost all sites exceeded the state standard for boating, 630cfu/100mL. During the two dry weather events in August, bacteria
concentrations ranged from 30 to 12,000cfu/100mL and dissolved oxygen
levels were lower than the Massachusetts Surface Water Quality Standards
of 5.0mg/L and 60% saturation. Click here
for the water quality results tables.
During the November
and May storm events, water quality was far
worse with concentrations of bacteria at three out of the six sites
ranging from 7,000 to 57,000cfu/100mL. These
extremely high levels of bacteria may have been indicative of illicit
connections to the stormwater drainage system. Also of water quality concern were the elevated total suspended
solids (TSS) concentrations, which were as high as 30mg/L, and the
elevated total phosphorus levels at all monitoring sites, which ranged
from 0.15 to 0.22 mg/L, exceeded 0.02375 mg/L, US EPA’s recommended
total phosphorus criteria in Level III, Ecoregion XIV.
In addition to the degraded instream water quality,
large amounts of trash, including items indicative of sanitary waste, were
observed both along the banks and in the brook during all three monitoring
events. See
sampling
map , sampling site descriptions , Canterbury
Brook photos , and
water quality monitoring
results for further information about Canterbury Brook.
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WATERSHED INFO
