American Journal of Climate Change, 2022, 11, 197-229 https://www.scirp.org/journal/ajcc ISSN Online: 2167-9509 ISSN Print: 2167-9495 DOI: 10.4236/ajcc.2022.113010 Sep. 28, 2022 197 American Journal of Climate Change The Influence and Implications of Climate Change on Water Quality in a Large Water Reservoir in the Southwest, USA Deena Hannoun * , Todd Tietjen, Keely Brooks Southern Nevada Water Authority, Henderson, NV, USA Abstract Maintaining water quality in large reservoirs is crucial to ensure continued delivery of high-quality water to consumers for municipal and agricultural needs. Lake Mead, a large reservoir in the desert southwest, USA, is projected to be affected by both loss of volume and rising air temperatures through the end of the 21 st century. In this study, reductions in lake volume, coupled with downscaled climate projections for rising air temperatures through the end of the 21 st century, are incorporated into the 3D hydrodynamic and water quali- ty model for Lake Mead. If current management practices continue in the fu- ture, simulations indicate water temperatures will increase in all scenarios and could increase by as much 2˚C under the most pessimistic scenarios, but nutrient loads would not increase to concerning levels. Releases from the dam to downstream users are projected to be much warmer, and warmer water temperatures and significant dissolved oxygen in the water column are ex- pected to cause challenges for ecosystem and recreation in the future. Surpri- singly, during the Winter and Autumn, retention of heat in Lake Mead is more pronounced at higher surface elevations than the lower elevations as expected. The effects of these projections on the lake water quality and con- sequently, lake management decisions, are discussed. Keywords Climate Change, Lake Management, Water Quality Modeling, Lake Mead, AEM3D 1. Introduction Reservoirs are important sources of drinking water, and they, like other bodies of water, are being impacted by decline in water quality due to climate change How to cite this paper: Hannoun, D., Tiet- jen, T. and Brooks, K. (2022). The Influence and Implications of Climate Change on Water Quality in a Large Water Reservoir in the Southwest, USA American Journal of Climate Change, 11, 197-229. https://doi.org/10.4236/ajcc.2022.113010 Received: May 12, 2022 Accepted: September 25, 2022 Published: September 28, 2022 Copyright © 2022 by author(s) and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY 4.0). http://creativecommons.org/licenses/by/4.0/ Open Access