Simulating THM Formation Potential in Sacramento Delta. Part I

TWO empirical relationships are developed that describe bromide impacts on the distribution of trihalomethane (THM) compounds measured by California's Department of Water Resources (DWR) THM formation potential test. These relationships are based on 2,000 channel and agricultural drain samples collected over eight years in the Sacramento‐San Joaquin Delta, a tidal estuary that is the source of drinking water for 20,000,000 Californians. One relationship, the bromine incorporation factor, describes the extent of THM bromination for a given test as a function of a surrogate bromide‐to‐precursor ratio. A second relationship, the bromine distribution factor, defines the distribution of THM species formation as a function of the bromine incorporation factor. These empirical relationships will be employed by DWR in conjunction with a numerical transport model as a planning tool to compare impacts of source‐water management alternatives on export water quality. An example problem illustrates the role of these empirical relationships within such a framework. An application of this new planning tool is presented in a companion paper.