Colorado River Basin Study Lower Basin Perspective August

Colorado River Basin Study Lower Basin Perspective August 15, 2013

Summary • Climate Change Hydrology – Planning for the Worst Case • Portfolios • Conservation and Reuse Options • Next Steps

Colorado River Basin Water Supply and Demand Study • Purpose – Assess future water supply and demand imbalances over the next 50 years – Assess risks to Basin resources – Develop and evaluate opportunities for resolving imbalances and to mitigate impacts to resources • A planning study – will not result in any decisions, but will provide the technical foundation for future activities

Projections of Natural Flow at Lees Ferry 13. 7 MAF Annual Flow, million acre-feet 15. 0 MAF • The Downscaled GCM Projected scenario indicates higher variability and a mean less than other scenarios, ~ 9% less than the observed record by 2060.

Historical Lake Powell Annual Inflows 2000 – 2008: Natural Flow 11. 8 Million Acre-Feet or 79% of Average 160% 139% 140% 120% 105% Normal 100% 80% 60% 40% 102% 88% 73% 68% 62% 59% 73% 51% 45% 40% 25% 20% 0% 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 Proj. 2013 10 -Year Average (2003 -2012): 80% of normal Historical 13 -Year Average Inflow: 73% of normal

Future Colorado River Water Supply and Demand • Median supply and demand imbalance in 2060 is 3. 2 million acre-feet / year • The range of supply and demand imbalances ranges from 0 to nearly 8 million acre-feet / year

Portfolios B and C • Portfolio B – More reliability – Includes augmentation projects (importation and ocean desalination) • Portfolio C – More energy sensitive – Augmentation projects are not included (less water available by 2060)

Portfolio Profile Resource Options and Volumes in Million Acre-Feet 0, 972 1, 150 Reuse Local Supply Importation 0, 100 0, 075 0, 600 0, 000 Desalination Energy Water Use Effciency 1, 476 0, 620 0, 160 M&I Consevation 1, 000 Agricultural Conservation 1, 000 Watershed Management 0, 300 Portfolio B (5. 608) 0, 730 Portfolio C (4. 735)

M&I Conservation Options • 27 submitted options related to M&I conservation • Includes conservation measures for: – – Residential indoor Commercial, institutional, and industrial Outdoor landscaping Water loss demand • Computed potential savings for Study Area and translated to potential Colorado River savings

M&I Conservation Options • 3 representative options, reflecting 3 levels of additional conservation at a Basin-wide level, were developed – Best Management Practices and adoption rates derived from state of Colorado and California approaches were used to determine amounts • Conservation from options was assumed to be in addition to the amount of conservation embedded in the demands scenarios

M&I Reuse Options • 11 submitted options related to reuse • Reuse options include: – Municipal wastewater reuse (932 KAF) • Non-potable (in AZ, CA, CO, NM, UT, & WY) • Indirect potable (in AZ & CA) – Industrial wastewater reuse (40 KAF) – Grey water reuse (178 KAF) • Considered state water law when assessing reuse potential

Agricultural Conservation Options • 9 submitted options • Classified into 6 conservation measures – – – Advanced irrigation scheduling Deficit irrigation On-farm irrigation system improvements Controlled environment agriculture Conveyance system efficiency improvements Fallowing of irrigated lands • Computed potential savings for Study Area and translated to potential Colorado River savings – 2. 44 MAF in study area; 1 MAF of savings to Colorado River

Development of Representative Options: Agricultural Conservation • 2 representative options, reflecting 2 implementation approaches at a Basin-wide level, were developed • The implementation approaches considered are agricultural conservation with and without transfers, up to 1 MAF for each approach was evaluated (not additive)

Uncertain • How big will the imbalance be? • Can we achieve an additional 3 million acre-feet / year by 2060 through conservation, reuse, and agricultural transfers?

Certain • Need a supply of water to bring into the Colorado River Basin • Augmentation Projects deliver known volumes of water (many years to build)

Lower Basin Shortage – Exceeds 1. 5 MAF Over 5 Years 70% Percent of Years Vulnerable 60% 50% Baseline 40% Portfolio A Portfolio B 30% Portfolio C Portfolio D 20% 10% 0% 2041 -2060

Lake Mead Pool Elevation Below 1, 000 feet

Next Steps We have a problem We are all in this together Additional Conservation and Reuse Analysis regarding actual water savings to be gained Augmentation Begin feasibility studies – must bring water into the Basin

Call to Action • Possibility of supply and demand imbalances in the Colorado River Basin identified as early as 1960’s • Greater uncertainty because of climate change • Various options and strategies take years to develop • We must start now

SOUTHERN NEVADA WATER AUTHORITY