Sources of Disinfection Byproduct-forming Material in the State Water Project

Science Center Objects

Water from the Sacramento-San Joaquin Delta contains high concentrations of disinfection byproduct-forming (DBP-forming) materials when treated for potable use. DBPs form when dissolved organic compounds (DOC) in water react with disinfectants such as chlorine and ozone during the water-treatment process. The amount of DBPs that form is a function of the amount and source of the DOC, both of which can vary significantly over a period of days. Epidemiological studies have linked several DBPs to increased occurrence of bladder cancer, miscarriages, and leukemia. Treated Delta water frequently exceeds DBP concentrations permitted by U.S. Environmental Protection Agency regulations.

A variety of natural and anthropogenic processes affect the concentration and composition of DOC in the Delta. Presently, there is little information available regarding historic levels and trends in the amount and composition of DOC released from, for example, in-channel biological production, wetlands, agricultural sources, island drains and the myriad of other DOC sources present in a system as large and complex as the Delta and its watersheds. To quantify potential changes, the baseline levels and current trends must be characterized and understood.

The objectives of this project are to:

  1. Characterize historic levels and trends in DOC and DBP-forming material in the Delta.
  2. Quantify the major processes controlling DOC concentrations and composition in the Delta.
  3. Develop analytical models for predicting levels of DOC and DBP-forming material in the Delta based on measurable properties in the Sacramento and San Joaquin River systems.
  4. Identify future monitoring strategies, locations, and parameters that will most effectively improve our ability to assess changes in levels of DOC and DBP precursors.
  5. Develop statistical tools that can be used to estimate relative impacts of proposed CALFED changes on DOC and DBP precursors in the Delta.