A study of public response to the proposal to divert flood waters from the Connecticut River at the Northfield Mountain pumped-storage hydropower plant to Quabbin Reservoir, Boston's major water supply impoundment, showed that opposition, while appearing to be broadly based, was actually limited to a relatively few knowledgeable, highly motivated individuals whose efforts delayed project approval but did not succeed in significantly influencing public officials and decision-makers. The study includes a discussion of potential environmental impacts based on available but generally scanty data. Also included are appendicies dealing with: Historical, political, and social factors affecting public policy on river diversion; Annotated bibliography and comments on sedimentation in the Connecticut River; Effects of water diversion of the Connecticut River on the biology of anadromous fish; The role of flood flows in the eutrophication and pollution of the Connecticut River; Role of Connecticut River flood flows in recharging ground-water formations.