Memorandum from Region 8 Inventory and Monitoring Hydrologist to Don Edwards San Francisco Bay NWR Refuge Manager regarding review of data quality from continuous water quality sensors installed in two units at the refuge. An interpretation of water quality characteristics is provided, as well as recommendations for future improvements to monitoring protocols. Hydrolab continuous water quality sensors that measure temperature, dissolved oxygen (DO), specific conductivity (SC), salinity, and pH were deployed in late summer (August through early October) at two stations at the Don Edwards San Francisco Bay National Wildlife Refuge (DESFBNWR): A16 and SF2. Both sites are deployed at the discharge channel for pond units A16 and SF2, which are the terminal units for a multi-unit flow system. Site SF2 is located at 37°29'26.85"N and 122° 7'38.26"W. Site A16 is located at 37°26'35.17"N and 121°57'42.57"W. Data are used to report to the California Regional Water Quality Control Board (San Francisco Bay) to maintain compliance with discharge permits. Refuge staff has requested assistance in reviewing the collected water quality data to ensure accuracy and to interpret water quality characteristics of the outflow to both units. The purpose of this letter report is to a.) provide a review of the data quality to ensure that data of extremely questionable accuracy are not reported to the RWQCB and that data are not misinterpreted, b.) interpret characteristics of water quality data based on what is known about the sites and the system, and c.) provide recommendations for improvement of water quality data collection and field maintenance procedures to better ensure data accuracy in the future.