CRWA volunteer Max Dulieu boats to the sampling site.
Since 2002, CRWA has partnered with boathouses in the Lower Charles River Basin to communicate potential public health risks to Charles River users during summer months. In the early years of the program, CRWA scientists would run recent rainfall data through simple models in Microsoft Excel first thing in the morning to estimate the concentrations of E. coli bacteria at four locations on the river: the North Beacon Street Bridge, the Larz Anderson Bridge, the BU Bridge, and the Longfellow Bridge. Our staff would then call boathouses to tell them which color flag they should fly: blue when there were no predicted public health risks and red when predicted E. coli bacteria levels exceeded the Massachusetts water quality standard for boating: 1,260 colony-forming units per 100 milliliters. CRWA also recorded predictions on a “hotline” that river users could call to find out the water quality predictions for the day.
The program has made incredible strides in the last 15 years. CRWA now operates a weather station on a small island near the Community Boating facility in Boston. The weather station records environmental data, such as rainfall, wind speed, and air and water temperature, every 10 minutes and uploads them to the internet every hour. The data are then automatically run through four separate complex models that predict E. coli bacteria concentrations hourly at the same four locations we have used since 2002. Although CRWA continues to announce water quality predictions via an email newsletter, Twitter, and phone calls to boathouses, river users and aficionados worldwide can check the latest predictions on our website at any time of day any day of the week between the Fourth of July and the Head of the Charles Regatta in mid-October.
This year, CRWA interns and volunteers collected 116 water samples on 26 different occasions between June 27th and October 20th. Only three samples exceeded the water quality standard for boating. One sample was collected at the North Beacon Street Bridge on October 18th after a localized rain storm. The other two samples were collected at the BU Bridge on June 30th and October 13th, after wet and dry weather, respectively. Although we had to temporarily retire one model that uses flow data from the USGS gage at the Moody Street dam due to this year’s drought, our water quality models correctly predicted flag colors for 97% of the season, our best performance yet, and an appreciable improvement over our 2015 model results, which were accurate for 92% of the season. The BU Bridge had the most red flag predictions in 2016 (5%), and is the only site that had more red flag predictions in 2016 than in 2015 (3.9, or 11 days).
CRWA will continue to use our sampling results from the 2016 season to improve our water quality forecasting models for the 2017 season. Check out our website next July to see the latest updates!