ColoradoJune 2021 Water CLIMATE CHANGE & ADAPTATION Colorado Water » June 2021 I Table of CONTENTS Features—Climate Change and Adaptation From Our Cooperators 3 How is Climate Change Impacting Colorado River Flow 32 The Water Problem: Historical Observations on By Brad Udall and Dr. Jonathan Overpeck Climate Change By Taylor Schulze 8 Evaluating Conserved Consumptive Use on High- Elevation Pastures in the Upper Colorado Basin 35 How Has Precipitation Changed Over Time Across By Dr. Perry Cabot, Aaron Derwingson, and Matt Bromley Colorado? By Dr. Becky Bolinger 11 The Agriculture Impact Task Force By Nora Flynn 40 Climate Change and Forest Regeneration: 12 Embracing Climate Change in the Colorado Water What to Expect and Where to Go By Dr. Ethan Bucholz and Dr. Amanda West Fordham Plan and in Local Communities By Russell Sands Also in this Issue 15 Colorado River Basin Climate and Hydrology: State of Science, A Synthesis Report to Support Water 46 In Memory of John Porter Planning and Management By Dr. Melissa Mokry By Elizabeth Payton and Jeff Lukas 47 Faculty Profile: Dr. Jeremy Rugenstein 19 New Research Explores Hard Truths for the Future of 48 Congratulations to the 2021-2022 CSU Competitive Colorado River Management Grant Program Awardees By Eric Kuhn and Lael Gilbert 50 Water Research Awards 23 Climate Change Mainstreaming at Denver Water 52 Water Calendar By Taylor Winchell and Laurna Kaatz 53 Recent USGS Publications 26 The Colorado Water Plan: Past, Present, and Future By Rebecca Mitchell ColoradoJune 2021 Water References can be found in the online version CLIMATE CHANGE & of this newsletter at watercenter.colostate.edu/ 29 Dirty Snow: Turning Qualitative Assessments into ADAPTATION water-news Quantitative Factors for the Effect of Dust on Snow By Caroline (Rosie) Duncan, Dr. Steven R. Fassnacht, On the cover — A campfire on the shore of Lake Powell pictured at night. ©iStock.com. and Jeffrey E. Derry 43 The CSU Climate Adaptation Partnership: Colorado Water » June 2021 I Connecting Research and Policy to Address the Cooperators include the Colorado State Forest Service, the Colorado Climate Challenges of Living with Climate Change Center, and CSU’s Water Resources Archive. By Dr. Courtney Schultz, Dr. Leisl Carr Childers, Dr. Niki The contents do not necessarily reflect the views and policies of these agencies, nor does mention of trade names or commercial products constitute their vonHedemann, and Tamera Breidenbach endorsement by the U.S. Government and Colorado State University. CSU is an equal opportunity university. Colorado Water. Fort Collins, Colo: Colorado Water Center, Colorado State University, 2021. Print. Volume 38, Issue 1 Published by Supported by Colorado Water Center This publication is financed in Colorado Water is a publication of Jennifer Gimbel, Interim Director part by the U.S. Department of the Colorado Water Center. The Julie Kallenberger, Associate Director the Interior Geological Survey, newsletter is devoted to highlighting through the Colorado Water Center water research and activities at CSU Editor and CSU’s College of Agriculture, and throughout Colorado. Melissa Mokry Warner College of Natural Resources, Agricultural Experiment Colorado Water. (2021). Design Station, and Extension. Colorado Water Center, R. Emmett Jordan watercenter.colostate.edu Colorado State University Production Director Nancy Grice Director’s LETTER elcome to “The thing about Reagan is that he was a our Spring kind person, above all else. He inspired me Wedition of the perhaps the most by showing that a person Colorado Water Cen- with great intellect and authority can also ter (CoWC) newsletter nurture positive relationships at every level, focused on climate from undergraduate students all the way change and adaptation. to the highest levels of state government. Jennifer Gimbel, JD It has been over five There are many other things to admire about years since we focused Reagan, such as his tireless work to improve on climate change and adaptation. Scientists have the Colorado Water Center, his encyclopedic continued to research and study climate change and knowledge of water literature, and his its effects. Thanks to the CoWC’s own Brad Udall and enthusiasm for all forms of water research, his colleagues for all their work and for sharing that he inspired me the most through his humility. information in this newsletter. His career will be defined by countless In December’s edition Dr. Reagan Waskom, former successes and achievements, but I believe Director of the CoWC, eloquently talked about his 34 that the larger legacy he leaves behind is years at Colorado State University (CSU), including 20 the standard he set for courtesy and respect, years at the CoWC. He spearheaded the research, edu- whether things were collegial or controversial. cation, and outreach of water sustainability and created He never wavered from his belief that a “safe” environment for discussions on many conten- positive relationships are the foundation for a tious issues in academia, Colorado, and the western successful and happy career.” water world. I personally respected Reagan for his kind- —Perry Cabot, ness, thoughtfulness, insight, and ability to lead difficult Research Scientist and Extension Specialist conversations by speaking softly and making quiet sug- gestions. Most of our readers interacted with Reagan in his many years of service. One aspect that has not “The thing Reagan taught me most was to been shared is what Reagan meant to the people who be unwaveringly committed to the objective worked for him, or as he would say with him. truth. He was very good at cutting through the fray and getting to the heart of a matter to analyze the facts in an objective and unbiased way. And Reagan was fiercely committed to the facts.” —Blake Osborne, Water Resources Specialist-Southern Region “Reagan was always a trusted source to throw ideas and thoughts at and always gave you great responses back as well as items to think about. If Reagan knew issues were coming forward, he always made sure you were in the loop, so there weren’t any surprises coming at you.” —Joel Schneekloth, Water Resource Specialist-Northern Region. Colorado Water » June 2021 1 Horsetooth Reservoir, ©iStock.com “It’s challenging to summarize the influence “As I reflect on the days when Reagan was Reagan’s leadership and mentorship had on my advisor, I realize how crucial his guidance both my professional and personal growth impacted and empowered my growth as in only a few sentences. Reagan provided a scientist and as a person. Reagan is a invaluable support and inspiration throughout generous mentor, passionate to share his my graduate studies and our work at CoWC. knowledge, and was always willing to share Like many others, I am the beneficiary of his valuable insights for building a successful Reagan’s many talents, including his ability to career. I am grateful for his continued support.” impart his vast water knowledge and shape —Panagiotis (Takis) Oikonomou, the next generation of water professionals. I Colorado Water Center Affiliate and am blessed to have worked with one of our Former Civil and Environmental community’s most respected and committed Engineering Post-Doctoral Researcher public servants.” —Julie Kallenberger, “What was so valuable for me, working Associate Director with Reagan, is that not only is he an “I really valued and respected that no matter extraordinary listener, he has a holistic how busy Reagan Waskom’s schedule was, perspective to bring to whatever issue is at he always made time to meet with faculty, hand. Rather than jump to easy answers, students, and the public. He was happy he was willing to spend some time with to mentor students and new faculty, and me, probing, looking for underlying he enjoyed watching them develop their factors, historical significance, and societal education and research careers.” implications. I miss having his perspective— and his wisdom.” —Nancy Grice, Assistant to the Director —MaryLou Smith, Former Water Policy and Collaboration Specialist Reagan’s legacy can be found in every aspect of CoWC: students, employees, academia, water users, western water discussions, and finally, in his vision of a new Western Water Policy Institute to be part of the SPUR campus in Denver. Thank you, Reagan. Your influence has given CoWC a solid foundation to move forward. Jennifer Gimbel, JD Interim Director, and Senior Water Policy Scholar, Colorado Water Center 2 Colorado Water » June 2021 How is Climate Change Impacting Colorado River Flow? Brad Udall, Climate Scientist and Scholar, Colorado Water Center Dr. Jonathan Overpeck, Samuel A. Graham Dean and Collegiate Professor, School of Environment and Sustainability, University of Michigan ince the 1970s, scientists have been interested in how runoff in the Col- orado River Basin (CR Basin) would change as the climate warms. Many of Sthese studies strongly suggested that the Colorado River (CR) would lose flow with warming, but in the last few years, scientists have been able to analyze a de- clining 22-year flow record, the ongoing 2000-2021 “Millennium Drought”. Multiple studies since 2016 have now found human fingerprints on the nearly 20% loss in flow since 2000 and attribute up to half of that loss to the approximately 1.2°C or more warming that has occurred during the last century. This article summarizes six key peer-reviewed studies related to the topic of CR flow loss. These studies have found declines in runoff efficiency, investigated the causes of flow loss, and in some cases made projections about future flow declines based on the 21st-century climate model projected temperatures. A high-water mark or “bathtub ring” is visible at Lake Powell, the second largest reservoir on the Colorado River. The bathtub ring is white because of the leaching of minerals on previously submerged surfaces. ©iStock.com Colorado Water » June 2021 3 Lake Granby stores Colorado River water and is the largest storage reservoir in the Colorado-Big Thompson Project and the second largest water body in Colorado.