Friends of the Rappahannock

Source Information

Members of the Frankel Lab at the University of Mary Washington monitor water quality at several locations along the Rappahannock River in partnership with the Rappahannock Group Sierra Club and other non-profit organizations. Monitoring for 2026 is generously supported by the JF Environmental Trust Foundation and the University of Mary Washington Undergraduate Research Grant Program. Monitoring occurs every week from February through November. Parameters tested include E.Coli, total coliform, pH, temperature, salinity, and turbidity. Detailed monitoring results can be found through the Chesapeake Monitoring Cooperatives Data Explorer, https://cmc.vims.edu/#/home The primary parameter of concern is E. coli, a fecal coliform. E. coli is measured in terms of the Most Probable Number /100 ml water and are indicators of fecal contamination by warm- blooded animals including birds and mammals. A “green” rating demonstrates that the level of E. coli at the time of sampling falls beneath the Virginia Department of Environmental Quality primary contact water quality safety standards as well as the DC and MD Primary Contact Water Quality Standards These Primary Contact Water Quality Standards are as follows: • E. coli single sample value = 410 MPN/100mL A red special status update indicates an abnormal situation such as a severe weather event, construction activity, or a combined sewage overflow (CSO) in the past 48 hours. This status means it is extremely likely there are unsafe levels of bacteria in the river, and it is recommended to be extra cautious if you are close to the river or come in contact with the water. A grey special status can also mean that there was no data collected that week due to high flow rates, park closures, or inaccessibility of the collection site. We encourage users to explore the sample data in addition to checking the swim guide status. These data can be viewed through the Chesapeake Monitoring Collaborative Data Explorer, https://cmc.vims.edu/#/homeedu