Water Quality Reports and Data
ORIGIN OF THE CRWA DATA AND How to Interpret it
CRWA’s Volunteer Monthly Monitoring (VMM) program analyzes river samples once each month at 35 locations in the watershed. These data, collected by more than eighty volunteers monthly since 1995, help CRWA study the health of the river and also assist municipalities, environmental agencies, and organizations who work to minimize stormwater impacts and reduce sewage contamination in the river.
Bacteria levels often change on a daily basis in the Charles River, in response to recent rainfall or snowmelt that washes pollution into the river. Thus, results only reflect the water quality on the sampling day and E. coli results may vary month to month based on how much rain fell before sampling. There is a delay between sampling and publishing of the data because samples take time to process in the lab, and for the results to be verified and processed by CRWA.
For these reasons, these monthly data are best utilized when identifying long-term trends over time.
Learn more about VMM and check open volunteering opportunities!
Bacteria levels often change on a daily basis in the Charles River, in response to recent rainfall or snowmelt that washes pollution into the river. Thus, results only reflect the water quality on the sampling day and E. coli results may vary month to month based on how much rain fell before sampling. There is a delay between sampling and publishing of the data because samples take time to process in the lab, and for the results to be verified and processed by CRWA.
For these reasons, these monthly data are best utilized when identifying long-term trends over time.
Learn more about VMM and check open volunteering opportunities!
HOW TO NAVIGATE THE DASHBOARD
This dashboard shows Charles River water E. Coli concentration by sampling site and over time. When aggregated over time, or over several sites, the concentrations are averaged (arithmetic mean). By default, the map and figures show the E.Coli concentration for the last 12 months of sampling events for all the sites.
To begin, please select the time period and sampling sites that you are interested in (on the top right, or from the list on the right of the map).
You can also select sites by zooming on the map itself, or by clicking on the selector icon on the top left of the map. If you hold shift while doing so, you can select several sites.
All data is shown according to the legend (underneath the map). See "About the health risk levels" section below for more details.
If you hover over each module (map, charts, etc.) you will see an icon pop up with four arrows. You can click this to expand the module, and view it in more detail.
The donut chart shows the percentage of sites that fall into each health-risk level, for the time period and site(s) selected. If you select one site, it will show the distribution of health-risk levels at that site, over the time period selected.
The gauge chart shows the average E. Coli concentration of the selected site(s), over the time period selected.
The line chart shows all the data at the select site(s) over time, and which level of health risk they fall into. You can use the slider above the graph to change the time period visible, and watch the graph change!
To begin, please select the time period and sampling sites that you are interested in (on the top right, or from the list on the right of the map).
You can also select sites by zooming on the map itself, or by clicking on the selector icon on the top left of the map. If you hold shift while doing so, you can select several sites.
All data is shown according to the legend (underneath the map). See "About the health risk levels" section below for more details.
If you hover over each module (map, charts, etc.) you will see an icon pop up with four arrows. You can click this to expand the module, and view it in more detail.
The donut chart shows the percentage of sites that fall into each health-risk level, for the time period and site(s) selected. If you select one site, it will show the distribution of health-risk levels at that site, over the time period selected.
The gauge chart shows the average E. Coli concentration of the selected site(s), over the time period selected.
The line chart shows all the data at the select site(s) over time, and which level of health risk they fall into. You can use the slider above the graph to change the time period visible, and watch the graph change!
about the health risk levels
The US Environmental Protection Agency (EPA) and the Massachusetts Department of Environmental Protection (MassDEP) sets water quality standards for E. coli bacteria to indicate the level of health risk in freshwater.
MassDEP recommends not swimming or fishing when the level of bacteria exceeds 235 colony forming units per 100 mL (cfu/100 mL) and not boating on days when the level of bacteria exceeds 1260 cfu/100 mL. This so-called “single-sample threshold” is used everywhere in the dashboard.
MassDEP recommends not swimming or fishing when the level of bacteria exceeds 235 colony forming units per 100 mL (cfu/100 mL) and not boating on days when the level of bacteria exceeds 1260 cfu/100 mL. This so-called “single-sample threshold” is used everywhere in the dashboard.
- Blue (Safe for swimming): E.Coli concentration is under or equal to 235 cfu/100 mL
- Yellow (Safe for boating only): E.Coli concentration is between 236 cfu/100 mL and 1260 cfu/100 mL
- Red (Not safe for activities): E.Coli concentration is above 1260 cfu/100 mL
HISTORICAL WATER QUALITY RESULTS
Additional water quality testing results are available for download in Microsoft Excel below. New data will become available as it is checked for accuracy. For more information on the parameters CRWA tests for on a regular basis, read CRWA Water Quality Monitoring Parameters. For questions regarding the following data, please contact Julie Wood.
- Ammonia 1996-2017
- Chlorophyll a and Phaeophytin 1997-2017
- Depth 1995-2017
- Enterococcus 1995-2017
- E. coli 2002-2017
- Fecal Coliform 1995-2002
- Nitrate plus Nitrite 1996-2017
- Orthophosphate 1996-2017
- pH 1995-2002
- Sodium 2007
- Temperature 1995-2017
- Total Suspended Solids 1996-2017
- Total Kjeldahl Nitrogen (TKN) 1996-2003
- Total Nitrogen 1997-2017
- Total Phosphorus (quarterly) 1996-2017
- Total Phosphorus (non-quarterly) 2005-2014
VOLUNTEER MONTHLY MONITOR REPORT