There are dozens of free events on the weekend of June 17th and 18th in celebration of the designation of the Sudbury-Assabet-Concord (SuAsCo) River as a Wild and Scenic River.
Experience the river through a variety of means: free canoe/ kayak and pontoon boating; walk with Thoreau along the Middlesex Canal; electro-shock river section to survey what fish are there; fishing derby; plein air painting; photo shoot; natural history, literary, and cultural history events; hike; bike; early morning wildlife and sunrise canoe/kayak trip from Bedford (followed by riverside breakfast); and culminating summer solstice music event at the Old Manse. Something for everyone.
See details here:
http://riverfest.sudbury-assabet-concord.org/
Special Bedford event:
http://riverfest.sudbury-assabet-concord.org/town/bedford