Long range surface water supply planning

considered to represent the "safe yield" from . . .. the Quabbin and Wachusett Reservoirs, the Recent projections Indicate that principal sources of supply. eastern Massachusetts must After a drought hat occurred uring the expand its surface water supply mid-1960s that se~~ed as a warn in? to the . area water authorItIes, several studies were system to deuver an adequate undertaken. In 1969, the U.S. Army Corps of supply during the coming Engineers estimated a potential shortage of decades. Understanding the up to 140 mgd in the MDC/MWRA supply . . area by 1990} In 1977, the now defunct New relatIonships among system England River Basin Commission projected storage, reliability and yield is a shortage of 77 mgd by 1990.3 In 1978, the essential to the solution of this Massachusetts Executive Office of Environ. mental Affairs estimated a shortfall of 70 long-range plannIng problem. mgd by 1990 for communities serviced by the MDC/MWRA.4 A current study by the RICHARD M. VOGEL & DAVID I. HELLSTROM MDC/MWRA, initiated in 1981, projects a shortfall of approximately 120 mgd by the A REPORT developed by the Metroyear 2020.1 politan District Commission (MDC) A principal ingredient of the MDC/MWRA and the Massachusetts Water study was to determine the "safe yield" that Resource Authority (MWRA) entitled, "Water the water supply system can deliver until Supply Study and Environmental Impact the year 2020. The choice of water sources Report," describes an enormous project to augment the existing water supply system which, if and when completed, will identify depends primarily on the knowledge of the the preferred alternative(s) for meeting the "safe yield" of both the existing system and projected water supply needs of the areas the sources under consideration, in addition . serviced by the MDC and MWRA until the to the forecasted demand for water. Figure I year 2020.1 In 1969, the demand for water 1 compares the system "safe yield" to the from the MDC/MWRA water supply system, demand for water over the past two , which services greater Boston and its centuries and illustrates the increasing short-