Charles River Water Quality Notification Flagging Program

CLICK HERE FOR TODAY'S FLAG COLOR!

Flagging Program Project Background Subscribe to daily water quality report Map of Flagging Sites  Muddy River Rain Gauge (Operated by USGS) 1998 to 2009 Complete Historic Data Monthly Water Quality Data Development of the bacteria prediction model for the Charles River (PDF) Watch a video of the flagging program (Get Real Player here) Flagging program home

Thank you for your interest in Charles River Watershed Association's summer water quality notification flagging program.

CRWA's Water Quality Notification Program presents the daily flag colors of the river's health, which signify whether or not the river is safe for boating at nine boating locations from Watertown to Boston. Flag colors are based on bacteria levels and blue-green algae counts. CRWA estimates bacteria levels using a model that takes into account antecedent rainfall conditions and if available, the previous day's bacteria sampling results. CRWA typically collects river samples for bacteria twice a week. Blue-green algae monitoring is conducted at least every two weeks.

A blue flag indicates suitable boating conditions

A yellow flag indicates inconclusive data to predict possible health risks

A red flag indicates potential health risks

For background information and more details on this project, click here.

Note: Due to budget constraints, during the weeks of September 28th and October 5th, water quality forecasts will not be verified by river samples. CRWA typically collects river samples twice a week which are analyzed at a private laboratory for bacteria concentrations. We will continue to publish daily water quality forecasts based on our bacteria concentration predictive model and instream monitoring of cyanobacteria concentrations.

Click here to see today's flag color!