Our rivers each have their own character that changes as they flow from south to north, passing over old dams in mill towns and meandering past wetlands, forests, and homes. Along with unique characters, each segment also has its own set of challenges.
Invasive aquatic plants: water chestnut
Excessive nutrients, sedimentation, and slow flow in impounded sections provide ideal conditions for invasive water chestnut and other invasive aquatic plants to thrive. Introduced in the 1870s in the Sudbury River, water chestnut (Trapa natans) rapidly spread to the other rivers, lakes, and ponds in the watershed and even across the country. Water chestnut is a rapidly reproducing annual plant; its hard nuts can lie dormant in the sediment for 10–12 years. Only consistent plant removal every year before they drop their nuts can keep them at manageable levels. A management plan for the watershed guides efforts by OARS, other non-profits, the US Fish and Wildlife Service, and municipalities. Mapping methods are being developed so that progress can be monitored and graded in the future; it is not yet included in the grade calculations.
Accessibility
Abilities
River recreation is an important activity for those with mobility impairments, declining balance, or other physical impediments to getting into a boat. Boating is very popular with retirees, but they may find it too difficult to get into and out of the water. Handicapped-friendly and ADA-compliant docks and paths will benefit a wide range of people. OARS’ river recreation maps describe accessibility at put-ins. See: Recreation.
Public transportation
Many people love to fish and hike along the rivers, but it’s hard to access these activities without a car. We found that public bus or train lines can get people close to most sections of the Sudbury and Concord Rivers, as well as a growing network of multipurpose/rail trails for foot and bicycle traffic along all three rivers.
Fish edibility
The three rivers provide excellent recreational catch-and-release fishing and are well known for their bass and other warm-water fish. Rivers meet the “fishable” standard when they have a healthy, reproducing fish population. River contamination affects the health of the fish and other aquatic life. It can also affect the health of the people who rely on the river for fish for their families. All surface waters in Massachusetts contain enough mercury deposited from air pollution to make fish consumption unwise for children and women of childbearing age. Mercury contamination from the former Nyanza chemical plant in Ashland has made all fish in the Sudbury River downstream of the plant too contaminated to eat. With time, the mercury will become buried in the sediment, where it will do little harm. New mercury pollution may abate with stricter controls on coal-fired power plant emissions in the future. See: Recreation-Fish Consumption Advisories.
Swimmability
Swimming was a popular summer pastime in the lower Assabet and the Concord Rivers years ago; Thoreau had a favorite swimming hole on the Assabet! As the rivers get cleaner, we can look toward restoring swimming, which requires adequate deep water that is clear and with minimal bacterial pollution. OARS’ new bacteria monitoring program will tell us whether and when swimming in certain locations in our rivers will be safe. Bacteria can come from stormwater, pet waste, failing septic systems, illicit sewer connections to storm drains, and wastewater treatment plant bypasses during heavy storms. See: Recreation—Swimmability.
Contaminants of Emerging Concern
Many contaminants, such as pharmaceuticals, can now be measured in very low concentrations due to improved measurement methods. These chemicals may affect human and wildlife reproduction and health at extremely low doses, such as affecting the body’s hormonal system or causing cancer. Monitoring is only just beginning and is difficult because of the sheer number of such chemicals and the analysis cost. The presence of intersex fish in the Assabet and Sudbury Rivers indicates that this will need increasing attention. Learn more.
Climate resilience
A resilient river system can accommodate floodwaters during storms, keep flowing during droughts, and support a healthy diversity of aquatic plants and wildlife. This, in turn, protects our drinking water supplies, recreational enjoyment, property, roads and bridges, and quality of life, and reduces the impacts of climate disruption on our lives. Restoring and protecting floodplains and wetlands, avoiding non-essential water use, and recharging stormwater into the ground all build resiliency. See: Habitat—Impervious cover.