SOME BIG ISSUES FOR A

May 11, 2017

Eric Kuhn

COLORADO RIVER BASIN

• Every drop of water is used • Total storage exceeds 4 times the annual mean discharge • Sophisticated & complex management • Connected to the Sac – SJ Delta via MWD • Exports are a major use • 2007 Interim Guidelines Transmountain diversions (to east) and downstream demands (to west)

450,000 to 600,000 acre-feet / yr 6,000,000 to 8,000,000 acre-feet/yr 1922 Colorado River Compact

• Divides the Colorado River (incl tributaries), into an Upper and Lower Basin

• Boundary between the two basins is Lee Ferry, Arizona

• Lower Division: Nevada, California & Arizona

• Upper Division: Wyoming, Colorado, New Mexico & Utah

• Arizona, Utah and New Mexico have lands within both basins Colorado River Compact of 1922 Colorado, like all Upper Division states, shares obligations to the Lower Division • III (d) the Upper Division shall “not cause the flow of the river at Lee Ferry to be depleted below an aggregate of 75,000,000 acre-feet for any ten consecutive years.” • III (c) regarding Mexico…the Upper Division must “deliver at Lee Ferry water to supply one-half of the deficiency so recognized in addition to that provided in paragraph (d).” Upper Colorado River Basin Compact of 1948 Purposes of the 1948 Compact include:

• “…equitable division and apportionment of the use of the waters…apportioned in perpetuity to the Upper Basin”

• “…establish the obligations of each State of the Upper Division with respect to deliveries of water required to be made at Lee Ferry”

• procedures and methodology for determining how much water Colorado would have to provide in the event the “curtailment of the use of water…becomes necessary in order that the flow at Lee Ferry shall not be depleted below that required by Article III (of the 1922 Compact).” Upper Colorado River Basin Compact of 1948

Provides Arizona with 50,000 AF per year, the remainder as follows: 51.75% to Colorado 23.00% to Utah 14.00% to Wyoming 11.25% to New Mexico

“Consumptive use” is defined as man-made depletions to the natural (undepleted) flow at Lee Ferry. (NOTE: This definition includes CRSP reservoir evaporation.) OTHER MAJOR COMPONENTS of the “LAW of the RIVER” • 1928 Boulder Canyon Project Act • 1944 International Treaty with Mexico • 1956 CRSPA • 1964 AZ v CA Decision and Decree • 1968 Colorado River Basin Act

Hydrology comparison average annual inflows at Lee Ferry • 2000-2014 12.3 MAF/year • 1988-2014 13.2 MAF/year • 1906-2014* 14.8 MAF/year • 1120-1172 T 12.7 MAF/year • Basin Study CC 13.7 MAF/year CC = climate change * = gage period T = paleo-hydrology based upon tree rings

Data from Reclamation’s Naturalized Flows database

Contingency Planning • Challenge from US Dept of Interior: • What if the current drought were to continue into the future? • Have a plan in place by 2015 (MOA or similar) • The Goal: • Identify actions that can reduce the risk of losing power production or being unable to deliver water • Possible Solutions: • Extended Operation of CRSP reservoirs • Demand Management • Cloud seeding / other augmentation Lake Mead Elevation Since 2000

1,225 January 2000 91% Active Storage Structural 1,200 Deficit 1,175

1,150 12.52 MAF Release WY 2011 1,125

1,100

1,075

1,050 Hydrology 1,025

1,000 2001 2016 2018 2000 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2017 2019 2020

975 Projected 24 Month

Lake Mead Elevation (EOM) Projected 24 Month 8.23 MAF Releases First Shortage Tier

THE FUTURE

• IMPACTS OF FUTURE TEMPERATURE WILL INCREASE DEMANDS & REDUCE STREAM FLOWS • NEW USES A ZERO SUM GAME • PAST PROMISES & EXPECTATIONS ARE STILL A POLITICAL FORCE • SOLUTIONS WILL BE SYSTEMWIDE Lake Powell Releases • Controlled by the 2007 Interim Guidelines • Based on storage levels in both Powell & Mead • What happens in the LB impacts Powell and what happens in the UB impacts Mead • As long as Powell has storage - NO compact problems for UB Conclusions • Hydrology, Demands and Future Development levels matter, the higher the consumptive use in the UB the higher the risk to all users. • Contingency Planning is Essential, CRSP reservoir drought operations reduces the risk, but in more severe droughts (e.g., 1988-1993 & 2001-2005), demand management is also required • Some of the demand management volumes we are seeing in the model are very large and may not be feasible, so we need to consider the “trade-offs” and alternative strategies • Example: Demand Management Combined with a Water Bank: – Could limit the Annual impact to CU by spreading Conservation over many years – Would provide greater control over conserved water Current Use Estimates MAF/ year Upper Basin uses incl. reservoir evap. 4.0 - 4.5

Lower Basin mainstream uses 7.5 - 7.5 Lower Basin reservoir evap. 1.0 - 1.5 Lower Basin tributaries 2.0 - 2.5 Total Lower Basin 10.5 - 11.5

Subtotal 14.5 - 16.0 Add Mexico 1.5 1.5

TOTAL 16.0 – 17.5 Vulnerability: Lee Ferry Deficit