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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
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 Colorado River Basin Water Supply and Demand Study
Projections of Natural Flow at Lees Ferry 15.0 MAF 13.7 MAF • The Downscaled GCM Projected scenario indicates higher variability and a mean less than other scenarios, ~ 9% less than the observed record by 2060. Annual Flow, million acre-feet
Historical Lake Powell Annual Inflows 2000 – 2008: Natural Flow 11.8 Million Acre-Feet or 79% of Average Normal 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)
M&I Conservation Options • 27submitted 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)
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