Water samples collected last Thursday confirmed a cyanobacteria, or blue-green algae, outbreak in the Charles River Lower Basin downstream of the Massachusetts Avenue Bridge.
Cyanobacteria bloom at Broad Canal in Cambridge
When present in large numbers, cyanobacteria give the water a green, paint-like appearance and may produce toxins harmful to humans, dogs, and wildlife. Exposure to these toxins can cause eye, ear, and skin irritation. Emerging science shows a possible link to neurodegenerative diseases and a possibility of exposure by inhalation. Because cyanobacteria are most likely to release toxins as they die off, the health risks persist for about two weeks after cell counts decline to safe levels. In addition to the public health risk, by preventing light and oxygen from entering the water, cyanobacteria can smother fish and other aquatic organisms.
How can I reduce my risk during a cyanobacteria bloom?
- Avoid contact with the water in areas effected by a cyanobacteria bloom.
- In the event of contact with the water, rinse thoroughly.
- Consider refraining from boating during the bloom or boat in a section of the river that is not affected.
- Discourage your dog from swimming in or drinking the river water during a bloom.
What causes cyanobacteria blooms?
The current bloom, the first documented this summer in the Lower Basin of the Charles, is part of an increasing trend as warmer summers and polluted stormwater provide ideal conditions for cyanobacteria to thrive. The Charles has experienced one or more cyanobacteria blooms in nine of the past eleven summers. The growth of cyanobacteria is fueled by phosphorus pollution accumulated on roads and parking lots, which is discharged into the Charles River via storm drains. An August 22nd rainstorm combined with the hot summer temperatures and the near record low flows in the river due to the extreme drought contributed to this outbreak.
According to U.S. EPA, the relationship between high phosphorus levels from stormwater discharges to the Charles River and the proliferation of cyanobacteria is well-established. Phosphorus is present in the Charles at more than twice the level the river can safely handle. However, there is a solution to this problem. Green infrastructure, such as rain gardens and constructed wetlands, filters polluted stormwater, reducing phosphorous pollution to the Charles River.
What can I do to prevent cyanobacteria blooms?
- Plant a rain garden on your property to filter stormwater and prevent it from entering the Charles River.
- Replace impervious areas such as driveways and patios with permeable pavers or porous pavement.
- Encourage your community to use green infrastructure to better manage polluted stormwater.
- Avoid using fertilizer on your lawn or garden. If you do use fertilizer, make sure it is phosphorus-free.
- Bring your car to a car wash that recycles water. This saves water too!
How can I help track cyanobacteria blooms?
Help CRWA and the Northeast Cyanobacteria Monitoring Program monitor cyanobacteria blooms in the rivers, streams and lakes near you. If you spot a portion of the Charles River or other waterbody that has turned the color of pea soup or looks like a blue-green paint spill, it may be a cyanobacteria bloom. With the new bloomWatch app, you can easily submit a picture and report the bloom.