Chemistry major and environmental studies concentrator examines city’s drinking water

Most students at Holy Cross get involved in the Worcester community through exploring the city’s dining and cultural establishments or getting involved in community service. M. Brenna McNamara ’07 of Exeter, N.H, opted for a more unconventional route — studying the city’s drinking water.

In the summer and into the fall of 2006, McNamara analyzed drinking water quality data collected over the past several years by the Department of Public Health and the Worcester Water Treatment Plant in the City of Worcester. Her goal was to try to find out the cause of the occasional findings of bacteria in the water during the spring and summer months.

A chemistry major and an environmental science concentrator, McNamara worked with James Bonofiglio, leading scientist at the Worcester Water Treatment plant to explore possible causes. She used the multi-year data set to systematically test each of six different hypotheses. McNamara concluded that the most likely explanation is regeneration. Undetectable damaged bacteria in the water leaving the water treatment plant may actually repair itself under the right conditions.

Perhaps the most surprising result McNamara found was the measurement of total coliform, which is required by law, was not a good predictor of fecal coliform, the actual bacterial strain that is harmful to humans. Indeed, fecal coliform has never been detected in Worcester’s drinking water since the Water Treatment Plant was built and these kinds of measurements were begun. Interestingly, the Environmental Protection Agency (EPA) uses occurrences of coliform bacteria to indicate if more harmful contamination may be present. McNamara’s thorough research calls into question the reliability of such a method.

Chemistry professor Jane Van Doren oversaw the research, but says it was ultimately McNamara’s own project. She says, “Brenna was using their data to try to solve the problem, and she did a great job.”

In March of this year, McNamara traveled to Chicago to present her findings at the American Chemical Society’s 233rd National Meeting and Exposition. Fourteen other Holy Cross chemistry students as well as some faculty and staff also exhibited their research.

“It was really rewarding to work with the water department to tackle a problem affecting both the Holy Cross community and the Worcester community as a whole,” says McNamara.

She added, “It was interesting to see how complicated real world scenarios are, but that you can also use a scientific background to solve problems.”