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CRWA Baseline Water Quality Monitoring
Volunteer Monthly Water Quality Monitoring Project
How to Interpret CRWA Data
On a monthly basis, CRWA collects water samples from 35 sites
along the entire length of the Charles River. Previously CRWA
analyzed all of the samples for fecal coliform bacteria. However in
anticipation of the water quality standards changing from fecal coliform
bacteria to Escherichia coli (E. coli) bacteria, CRWA has made the switch
and now collects and analyzes samples for E. coli. E. coli bacteria
is a better indicator of health risks. In the past, CRWA's
laboratory analyzed samples for fecal coliform bacteria, which is one
parameter used by the state for surface water quality standards.
According to the U.S. Environmental Protection Agency
and Massachusetts Department of Environmental Protection (DEP),
the swimming standard for E. coli is 126 colony forming units per 100
milliliters (cfu/100mL) and the boating standard is
The standards for fecal coliform are set by the Massachusetts Department of Environmental
Protection to indicate level of health risk. The DEP recommends not swimming
or fishing when bacteria counts exceed 200cfu/100mL, and not boating on days when
levels rise above 1,000cfu/100mL.
In conjunction with collecting water samples for
bacteria, in-situ measurements of temperature, and depth are also
conducted on a monthly basis.
On a quarterly basis, in March, June, September, and December,
CRWA takes a closer look at the water quality of the Charles River. Besides
E. coli, additional testing is conducted for enterococci, nitrate plus nitrite, ammonia,
total kjeldahl nitrogen, total nitrogen, phosphorus, orthophosphate, chlorophyll
a, and phaeophytin. From 1995 through 1997, river samples were
analyzed for biochemical oxygen demand, however, due to consistently low
levels, testing for biochemical oxygen demand was discontinued.
Click here for a list and
explanation of parameters CRWA tests for on a regular basis.
For further information about CRWA’s methodology for
water testing, or if you are interested in volunteering to collect water
samples, please contact CRWA's Volunteer Coordinator
at 781-788-0007 x228.
Click here to return to the Monthly Water Quality Monitoring home page