**6. Conclusions**

In this paper, we assess a set of future water supply scenarios for LADWP, which markedly increase local water sources including water recycling, stormwater capture, and conservation in order to support reliable and resilient water supply. We evaluate these scenarios as possible pathways for achieving the city's sustainability water targets using indicators to track the performance of each scenario in terms of electricity demand per unit of water, emissions per unit of water, daily water use per person, and annual electricity demand per person. We estimate the energy requirements for adopting each new water portfolio through 2050 and find that major shifts in water supply sources (i.e., from imports to local supplies) might not significantly change overall energy requirements, but they will change the distribution of the water-related electric load for LADWP's electricity balancing area and other electric load serving entities. Expanding groundwater recharge projects will add additional electric demands on LADWP's electricity system that could be more than 6 times the historical water supply-related electricity demand of LADWP's territory. By contrast, non-LADWP electric load serving entities will likely experience lower electricity demands due to reduced water imports that are transferred over long distances from the city. The decomposition analysis concludes that aggressive conservation measures are important to offset the growth in water demand and the effects of population increases, but the total electricity demand intensity of the water supply has the highest impact on the energy requirements of the water sector in most scenarios.

Our results emphasize that if the City's local water supply adoption occurs at a faster rate than its decarbonization goals in the power sector, those water policies might cause an interim increase in greenhouse gas emissions across LADWP's service territory (due to the increased electricity demand for water) which will be in conflict with the City's goals for mitigating future greenhouse gas emissions. Moreover, this potential growth in electricity demand within LADWP's network might increase other environmental externalities from power generators serving the utility (e.g., increased air pollution and cooling water needs), while non-LADWP regions might benefit environmentally from reduced electricity generation. Thus, evaluating the electricity demands associated with the expansion of a more drought resilient local water supply is important to meeting the multi-faceted sustainability goals of the city, especially those related to clean energy systems.

**Author Contributions:** Conceptualization, A.Z. and K.T.S.; methodology, A.Z. and K.T.S.; formal analysis, A.Z.; investigation, A.Z.; data curation, A.Z.; writing—original draft preparation, A.Z.; writing—review and editing, A.Z. and K.T.S.; visualization, A.Z.; supervision, K.T.S.; project administration, K.T.S.; funding acquisition, K.T.S. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by Los Angeles Department of Water and Power through Los Angeles 100% Renewable Energy Study, gran<sup>t</sup> number ACT-8-LADWP-03.

**Acknowledgments:** The authors would like to thank the professionals at the Los Angeles Department of Water and Power that helped inform the assumptions utilized in this study.

**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.
