**5. Program Accomplishments & Future Directions**

CDWR's MWQI program is the most extensive and cohesive program established to investigate the quality of Delta source water with respect to its suitability for production of drinking water. The program has met this goal over its first three decades of

existence by evolving in response to regulatory drivers, technology innovations, and an ever-increasing knowledge base developed through monitoring, targeted scientific studies, and computer modeling. In its successful quest to follow the recommendations set forth by an expert panel in the early 1980s [34], the MWQI program has accumulated several notable accomplishments:


The MWQI program, an on-going collaboration between CDWR and participating water agencies, has been designed and managed to be flexible and pro-active in order to address new drinking water quality challenges as they arise. The program's monitoring network, its frequency of data analysis and reporting, and its modeling tools—all of which have evolved over the past three decades—are collectively an effective "finger on the pulse" for Delta and SWP water quality that allow program participants to proactively manage risks by adjusting treatment processes, changing source water blends, or applying other operational tools to obtain optimal source water quality. Given the program's founding principles that drinking water quality concerns will continue to change and that it must adapt to address new challenges, future directions will likely be guided by a host of factors that may trigger changes in treatment plant processes and operations and Delta source water quality, including (but not limited to) identification of emerging contaminants, changes in land and water management practices, Delta island flooding, sea level rise, and climate change [132].

**Author Contributions:** P.H.H.; S.B.R.; S.W.K. and L.P. have contributed to the writing of this manuscript. All authors have read and agreed to the published version of the manuscript.

**Funding:** Funding for this work was provided by the State Water Contractors MWQI Specific Projects Committee.

**Data Availability Statement:** This work does not include primary data; all data referred to are available from their original publications or from the public websites that are cited.

**Acknowledgments:** The authors wish to acknowledge Bruce Macler (USEPA retired) for sharing his expertise related to the evolution of adopted water treatment technology and regulatory environment. We thank Richard Breuer (CSWRCB, retired), Carol DiGiorgio (CDWR, retired), Kevin Donhoff (MWDSC), Tony Liudzius (MWDSC), Cindy Messer (CDWR), and Shaun Philipart (CDWR) for their review of an early draft of the manuscript. We also thank Greg Gartrell (CCWD retired) for his review of an interim draft of the manuscript and his perspective on the early years of the MWQI program. Finally, we wish to thank members of the MWQI Specific Projects Committee for input on their current use of RTDF data.

**Conflicts of Interest:** The authors declare no conflict of interest.
