Water Quality Monitoring


Once a month, early on a Sunday morning, citizen scientists head out to sites along the Assabet, Sudbury, and Concord Rivers to collect water samples, measure pH, temperature and record river conditions. The data and analyses enable OARS, municipalities, environmental agencies, and others to improve management of our waterways.

Additionally, every week on Monday mornings, we have a team that collects samples for monitoring the health of the rivers for recreational purposes. This is a new initiative which will allow us to provide better information to river users about the safety of recreational water contact.

Volunteers are fully trained by OARS staff and all equipment is provided. To volunteer, please email OARS office.

This is your chance to make a real difference. Join our group of dedicated citizen scientists working to monitor and improve the water quality of our three rivers and their tributaries. To volunteer please email us

The 2019 sampling season starts in May. We sample on Sunday and Monday mornings (dates below). Sunday sampling generally starts at 5:30 am and takes about three hours. Monday sampling starts at 6 am and takes 1 hour. It is not necessary to be able to make all of the sampling dates, Volunteers can take turns to accommodate individual schedules.

Sunday Sampling: Teams of 3 volunteers each sample one section of the rivers (4 - 6 sites):

  • Assabet River, Westborough to Marlborough
  • Assabet River, Berlin to Hudson
  • Assabet River, Acton to Concord
  • Sudbury River, Framingham to Concord
  • Concord River, Concord to Lowell
    Sampling dates:
    Sunday, May 19th (start 5:30am)
    Sunday, June 16th (start 5:30am)
    Sunday, July 7th (start 5:30am)
    Sunday, August 11th (start 5:30am)
    Sunday, September 22nd (start 6:30am)
    Sunday, November 10th (start 8:00am)

Monday Sampling: Teams of 2 volunteers each sample one river (2 sites) weekly):

  • Assabet River (Hudson and Maynard)
  • Sudbury River (Ashland and Wayland
  • Concord River (Bedford and Lowell)

Information for volunteers only.