Every after­noon, North­eastern Uni­ver­sity grad­uate stu­dent Xioadan Ruan rides her bike along the Charles River, col­lecting water sam­ples at five poten­tial swim­ming areas.

Through a part­ner­ship with the Charles River Con­ser­vancy, Ruan is repeating that rou­tine each day for two months. The goal is to deter­mine where — and when — it is safe to swim in Boston’s most sto­ried river.

I always wanted to have a role in helping the envi­ron­ment, espe­cially in a city I am living in, and this project has really allowed me to put my skills to work in a way that can pos­i­tively affect the com­mu­nity,” said Ruan, who moved to the United States from China to pursue a PhD in envi­ron­mental engi­neering. She hopes to pub­lish the results of her study in a sci­en­tific journal.

Water is deemed safe for swim­ming when the pres­ence of Escherichia coli (E. coli), an intestinal bac­terium that is used as an indi­cator of fecal pol­lu­tion, falls below a cer­tain level.

Thus far, Ruan’s data shows that levels of E. coli are highest after a rain­storm, which causes con­t­a­m­i­na­tion from a com­bi­na­tion of sewer over­flow and storm water runoff. How­ever, on many other days, the levels have been at or below the stan­dards set by the U.S. Envi­ron­mental Pro­tec­tion Agency as safe for swimming.

The results of the mon­i­toring project will be used by the Charles River Water Quality Com­mis­sion to explore the fea­si­bility of returning public-​​access swim­ming to the Charles River.

Ruan is working under the direc­tion of Ferdi Hell­weger, an asso­ciate pro­fessor of civil and envi­ron­mental engi­neering at Northeastern.

Being able to col­lab­o­rate with the Charles River Con­ser­vancy is crit­ical to the suc­cess of this project,” said Hell­weger, who hopes that his ongoing research on water quality will help make the Charles River swim­mable once again.

Karen Peterson Greene, coor­di­nator for the Swim­mable Charles at the Con­ser­vancy, lauded the efforts of Ruan and said she looks for­ward to working with Hell­weger and others at North­eastern on future research projects.