*4.1. Defining Baseline Conditions: The Early Years (1990–1995)*

In 1990, CDWR merged IDHAMP, the Delta Islands Drainage Investigation, and other drinking water quality activities into the MWQI Program. The primary goal of this newly formed program was to assist water agencies in protecting and improving Delta drinking water supplies and to guide research on optimal water treatment processes. In the early years of the MWQI program, nominally between 1990 and 1995, this goal was achieved through continuity and expansion of previous monitoring activities (including monitoring key Delta channel and river stations and agricultural drains for constituents such as pesticides, arsenic, selenium, sodium, and THM formation potential) to characterize baseline conditions in the Delta. Efforts to fully characterize baseline conditions were confounded by persistent drought conditions: California endured a severe six-year drought spanning 1987–1992 with a brief return to drought in 1994. During this period, following a recommendation from the 1982 expert panel report [35], the MWQI program expanded efforts to incorporate information from the monitoring program into a comprehensive modeling framework. Finally, during this period, the program conducted its first SWP watershed sanitary survey. A summary of these early activities is provided below.
