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Battling Weeds in the Charles River: A Front-Line Report

Larry Smith, President, Charles River Canoe & Kayak

One hundred years ago, warm summer weekends would have seen the Lakes District of the Charles River dotted with paddlers in their canvas-covered canoes. These days the scene is not that different, with the fiberglass descendants of those canoes joined by colorful kayaks, rowboats, stand-up paddleboards, and pedal craft. Today, however, a major challenge presents itself: keeping the river clear enough to support continued recreational uses. As the Charles meanders through an increasingly developed watershed, storm runoff, parking lots, and fertilizers add phosphorus and other nutrients to the river in increasing concentration. These cause havoc with the natural balance of life in the river, which in turn can affect how the river can be used.


The Charles River contains a great diversity of flora and fauna, including many invasive species. The deep sediment and nutrient rich water supports invasive water chestnut, fanwort, and milfoil along with the non-indigenous American Lotus. The rapid spread of these plants has made many coves inaccessible and restricted boating and wildlife movement in the Lakes District of the Charles in Newton, Waltham and Weston. Concerned neighbors, businesses, and users have joined to raise money and prod government officials into action. This summer, over 100 tons of invasive weeds were removed with strong financial support from the neighborhood. Over 500 volunteers were assisted by a small mechanical harvester. Unfortunately, that effort hardly matched the weed growth, and a much larger 3-5 year effort will be required to control the most aggressive species, water chestnut. The management plan proposes that the State fund the initial cleanup effort and then yearly management continue at a much lower level funded through local efforts.


One indication of the nutrients in the river was this summer’s blue-green algae bloom. A blue-green algae bloom is a relatively unusual occurrence for the Lakes District. It does not restrict boating but has the potential to release toxins. The algae bloom and surrounding publicity did decrease rental activity at Charles River Canoe & Kayak in Newton. Fortunately, Charles River Canoe & Kayak has four other locations, which enabled classes and other activities that involved lots of contact with the water to be relocated. Rentals continued in Newton, and customers who called were informed of the situation. A few chose to visit the other rental locations in Cambridge, Boston, Nahanton Park, or Natick at Lake Cochituate State Park. No one reported any ill effects from the water, and washing facilities were available for those who were concerned. The algae bloom in the Lakes District cleared within a few weeks, and great boating returned by the last weekend in August.

September 2012

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