Four water quality monitoring sites have been selected on Mud Slough (north). Water quality data gathered at Mud Slough (north) will provide information regarding the impacts of the GBP on the Slough. Data will also be used to assess compliance with the CVRWQCB interim water quality goals and water quality objectives.

Site C is located upstream of the SLD discharges and will be used as a background or reference water quality site. Site D is located downstream of SLD discharges and will be used to evaluate impacts of the GBP on water quality of Mud Slough and for CVRWQCB compliance assessment. The specific location of sample collection for this site will be adjusted as necessary after SLD discharges are initiated. A spatial assessment of Mud Slough (north) downstream of the discharge will be conducted by measuring electrical conductivity, which will identify where complete mixing of the discharge with slough waters occurs. Water quality sampling for site D will be located at the bridge over Mud Slough unless it is determined that mixing of SLD discharge and Mud Slough has not occurred at the bridge, in which case the monitoring station will be relocated further downstream.

Site I is located in a Mud Slough (north) backwater area. Data from Site I will be used in conjunction with other data to assess potential impacts of flooding from Mud Slough (north) on backwater areas within Kesterson National Wildlife Refuge. Monitoring at Site E will provide water quality data to be used in conjunction with other data to obtain a mass accounting of selenium in natural aquatic environments.