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upcoming events

April 26
Mystic Community Earth Day events throughout watershed!
MyRWA Earth Day Cleanup with KEEN Footwear, 9AM, Blessing of the Bay Boathouse, 32 Shore Drive, Somerville 

May 6
Committee Meeting, 7-9PM
Tufts University, Lincoln Filene Center, Rabb Room
*Presentation by MyRWA on water chestnut plan for 2014

May 13
Flatbread Pizza Doughraiser, 5-11PM
Flatbread Pizza, 45 Day Street, Somerville

May 18
Mystic River Herring Run & Paddle, 8AM registration, 9AM 5K start, 11AM paddling races start
Blessing of the Bay Boathouse, 32 Shore Drive, Somerville

May 20
Friends of the Malden River Meeting, 6:30-8PM
Malden Public Library, Maccario Room, 36 Salem St, Malden


6 Sampling Locations Below:

View Cyanobacteria Testing Sites in a larger map


Current Sampling Data:
Click on the Graph for a larger view.

*Please note that cyanobacteria monitoring runs from June - August only.*


Since 2007, the Cyanobacteria Monitoring Program has monitored cyanobacteria levels throughout the watershed and alerted authorities of the potentially harmful bacteria.  Volunteers test water samples in recreational areas where there is a higher chance of contact with the toxic bacteria.

Cyanobacteria, also referred to as blue-green algae, are photosynthetic algae that grow in all types of water and are usually not visible to the naked eye except when they form colonies.  Blooms often occur from the late summer to early autumn and can appear overnight.  According to the CDC, “some [blooms] can look like foam, scum, or mats on the surface of freshwater lakes and ponds.  The blooms can be blue, bright green, brown, or red and may look like paint floating on the water.”  Harmful algae blooms can starve marine plant and animal life of oxygen, sicken humans and animals, and in some cases can result in damage of the nervous system and liver. Read the article Freshwater Algae Blooms: a newly recognized health threat, page 5, The Volunteer Monitor, Spring 2010, for more information about Cyanobacteria, including highlights of work done here in the Mystic River Watershed.

To decrease the chance of exposure to harmful blooms, avoid recreational activities such as swimming and boating in areas where the water looks discolored or there is surface scum, areas where notice of high cyanobacteria levels are posted, ingestion of water that is discolored or that has visible surface scum, and if you think you might have come in contact with harmful a cyanobacteria bloom, rinse off with fresh water as soon as possible.  It is important to note that pets can be just as easily affected by harmful cyanobacteria, and the same precautions should be taken. See the graphs below for Blessing of the Bay Boathouse in Somerville, Ell Pond in Melrose, Horn Pond in Woburn, Upper & Lower Mystic Lake in Winchester & Arlington, Shannon Beach in Winchester, Spy Pond in Arlington and Wedge Pond in Winchester.

For more in-depth information about what Cyanobacteria is, how to spot it, and the potential health risks, visit the Center for Disease Control’s page at:

*cell counts in cells/mL; the MA Department of Public Health has set an action level to 70000 cell/mL to protect human health.


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