Water Quality Conditions in the Sacramento-San Joaquin Delta and Suisun and San Pablo Bays during 2009

This report summarizes the results of water quality monitoring and special  studies conducted by the Environmental Monitoring Program (EMP) within the Sacramento-San Joaquin Delta (Delta) and Suisun and San Pablo bays (the upper San Francisco estuary) during calendar year 2009. This monitoring is mandated by Water Right Decision 1641 (D-1641) and this report is being submitted to fulfill the reporting requirements of this decision.

The EMP monitored water quality using a protocol implemented in 1996. Under this monitoring protocol, 13 sampling sites—2 of which were added after 1996—representing 8 regions of the upper San Francisco estuary (estuary) were monitored for 15 physical and chemical water quality parameters. The results gathered from the sampling of these 15 parameters are described in this report.

Parameters such as water temperature, Secchi disk depth, dissolved oxygen (DO) concentration, specific conductance, dissolved inorganic nitrogen, orthophosphate, and volatile suspended solids were within their historical range. Measured parameters exhibited seasonal variation as well as changes in response to significant rainfall events and in flow rates.

In addition to monitoring physical and chemical water quality parameters, biological sampling was conducted to monitor the productivity and community composition of phytoplankton, zooplankton, and benthic communities.