*4.3. Providing Decision Support for SWP Operations: The RTDF Years (2006–Present)*

The MWQI program was expanded during 2002–2006 with the incorporation of real time data collection and water quality forecasting. The expansion occurred in phases as new sensors and data dissemination were deployed (e.g., [108]); these new program elements are collectively referred to as Real Time Data and Forecasting (RTDF). For the purpose of this narrative, 2006 is defined as the first year when these elements were in stable operation. The objective of RTDF was to enhance the ability of drinking water agencies to make informed operational decisions based on observed and forecasted changes in Delta water quality [24]. Program activities during this contemporary era were documented in CDWR's Bulletin 132 series beginning in 2012 [5,109–111].

As part of this work, 14 participating water contractors were surveyed to understand their current use of MWQI's real time and forecast data. The survey asked each contractor about the locations where they monitor water quality and how their agency used the water quality data. Responses were then categorized and compiled as shown in Figure A3 (see Appendix A). The survey revealed that use of the RTDF website to check on current conditions was commonplace, especially data reported through real time sensors. The main use of MWQI water quality data is to provide an early warning of changes in source water quality. Contractors also reported special interest in metrics that might affect their water treatment processes, particularly over short-term horizons. Specific examples of contractor uses of RTDF data, obtained in the survey responses, include tracking (i) bromide concentrations to allow adjustment of ozone dosage during treatment, (ii) cyanobacteria levels to address potential taste and odor concerns, (iii) pH and alkalinity, which can affect treatment effectiveness, (iv) organic carbon concentrations (and related measurements) to plan for coagulant dosage, and (v) the contribution of San Luis Reservoir releases, which can affect water quality in the California Aqueduct relative to flows coming directly from the Delta.

To satisfy additional real time water quality data needs by the participating water contractors, monitoring of taste and odor compounds and cyanobacteria was initiated by the MWQI program during this era. Taste and odor compounds are sampled weekly all year throughout the SWP (at selected reservoirs, Delta pump station inlets and at selected locations on the California Aqueduct). Cyanotoxins are collected across the SWP system monthly in May and April, and twice a month from June to October. If toxins are detected, the sampling frequency is increased to weekly. These data have helped inform water contractor operations. Specifically, given that most of the participating water contractors have a defined trigger level for source water taste-and-odor compounds, such timely information can inform decisions related to real time water treatment. The MWQI program is currently evaluating real time sensors for chlorophyll and phycocyanin to possibly serve as early warning detection of harmful algal blooms.

The well-established MWQI program has also provided a unique environment for participating water contractors and CDWR to interact on a regular basis. It has become a forum where the contractors can bring their source water quality concerns to address either a new or proposed regulation or to seek assistance on issues related to the operation of the SWP. Ultimately, these issues may be resolved with other CDWR personnel outside of the MWQI Program, but the MWQI program serves as a resource for locating assistance. For example, water contractors received notification about a new herbicide (Endothall), which would be used to treat aquatic vegetation in the SWP. Due to water quality concerns about the residual herbicide concentration, the contractors and CDWR discussed the issue extensively at MWQI meetings and ultimately developed a monitoring plan to study the fate and transport of the herbicide in the SWP, which was implemented and supported by CDWR.

As another example of interagency coordination, CDWR periodically receives requests from water agencies to transport non-SWP water (typically groundwater) or to transfer water between agencies through the California Aqueduct. These are generally referred to as non-project water turn-ins. The water contractors have raised concerns about such requests in the past; these concerns have related primarily to groundwater quality. To address these concerns, the contractors collaborated with CDWR to establish a facilitation group, which sets an approval process (including minimum water quality criteria) for each turn-in request. An annual report is produced by CDWR to document turn-ins and their impact on downstream water quality [112].
