Water Quality in the State Water Project, 2000 and 2001

Water quality is routinely monitored at about 30 stations throughout the State Water Project (SWP). Water quality samples are collected by staff of the five field divisions in the Division of Operations and Maintenance and sent to Bryte Laboratory for analysis. SWP stations include those located in the Feather River watershed, North Bay Aqueduct, South Bay Aqueduct, and the California Aqueduct with its four terminus lakes in Southern California (Figure 1-1). Samples are collected on the third Wednesday of each month at the regular stations. Analyses include minerals, metals, metalloids, nutrients, organic chemicals, and disinfection by-product precursors.

Further, around 15 automated water quality stations continuously monitor parameters such as salinity and turbidity on a real-time basis. Station descriptions and water quality constituents analyzed are detailed in Appendix A.

Monitoring in the SWP is done on a routine basis to identify trends and assess water quality conditions with respect to long-term trends, operations, hydrology, seasons, emergencies, water treatment issues, and drinking water standards. Primary and secondary Maximum Contaminant Levels (MCLs) apply to drinking water and were compared to SWP data to provide a relative indication of raw water quality. MCLs are presented in Appendix B.

Water quality trend assessment focused on salinity, bromide, and organic carbon. Water quality in the California and South Bay Aqueducts was good during 2000 due, in part, to above normal water year conditions in the Sacramento and San Joaquin Valleys.

Drier conditions in 2001 resulted in less favorable water quality with respect to mineralogy. North Bay Aqueduct exports exhibited the usual impairments during winter as a result of organic carbon and turbidity increases. Water quality in the Feather River watershed was excellent, as usual, with low to non-detectable levels of minerals and minor elements.