When they gang up, they can turn a healthy bay or pond into a place of death. What people see are the blooms of algae, feeding on the excess nutrients. As the algae feeds and dies, it uses up the oxygen in a body of water. Starved for oxygen, fish die. The water stinks.
People complain and worry.
Brewster and Harwich residents are upset about algae blooms on Long Pond, the Cape's largest freshwater lake. Water quality is worsening in the inlets of Pleasant Bay in Orleans, worried monitors recently discovered. The bay is the main drain for hundreds of houses on the shore around Harwich, Chatham and Orleans and for new houses in subdivisions in Brewster. Even if the septic systems meet Title 5 standards, they still allow nitrogen, phosphates and other nutrients to enter the underground aquifer. Once in the aquifer, the nutrients are on their way to coastal waters.