[guryihnv] Draining the Charles River basin

A terrorist sabotages the dam at the base of the Charles River Basin reservoir between Cambridge and Boston, causing it to fully drain into Boston Harbor.

The dam and basin were originally constructed to cover up sewage-polluted tidal marshes which at low tide released diseases (typhoid?) infecting and killing Boston residents during certain seasons and weather patterns.

Note well that the basin merely covered up the problem rather than permanently solving it -- solving it would have required actually cleaning up the pollution! The deadly pathogens have shown the ability to survive anaerobically during high tide, so we speculate that they are still there and alive a century later in the polluted muck still present at the bottom of the Charles, a muck exposed by this speculative attack.

The terrorist thus accomplishes a very large-scale biological attack -- unleashing tons of pathogens -- for relatively modest effort.

This was originally written for Bruce Schneier's movie plot threat contest.