AWWA JAW18764

In 1979, an annual cycle of taste and odor episodes began in Lake Mathews, a storage reservoir that is part of The Metropolitan Water District of Southern California. In order to set up an early warning system that would detect impending taste and odor episodes, the utility developed a methodology for identifying the earthy-musty odors that plagued the reservoir, identified the agents causing the problems, studied the agents' habitat and distribution in the reservoir, and explored the various treatment methods available for controlling the agents. Advance notice has effectively been provided by the early warning system, which includes regular sampling of the reservoir in seven preselected locations. With this system, the utility has been able to minimize the severity and extent of annual taste and odor episodes. Thus far, application of chunk copper sulfate has proved to be most economical, but some concern exists that the algae may develop a resistance to the treatment. Includes 19 references, table, figures.