The Colorado River Big Issues for a “Not-so-big” River
Eric Kuhn, General Manager
State of the Gunnison RiversMontrose, Colorado - May 31, 2017
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 8,000,000acre-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 1922Colorado, 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).”
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
Upper Colorado River Basin Compactof 1948
Provides Arizona with 50,000 AF per year, the remainder as follows:
51.75% to Colorado23.00% to Utah14.00% to Wyoming11.25% 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
Courtesy of the Bureau of Reclamation
Natural Flow Colorado River at Lees Ferry Gaging Station, AZ
Vulnerability: Lee Ferry Deficit
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 waterPossible Solutions:
• Extended Operation of CRSP reservoirs• Demand Management• Cloud seeding / other augmentation
975
1,000
1,025
1,050
1,075
1,100
1,125
1,150
1,175
1,200
1,225
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
24 Month
2014
2015
Projected2016
2017
2018
2019
2020
Lake Mead Elevation Since 2000
Lake Mead Elevation (EOM) Projected 24 Month 8.23 MAF Releases First Shortage Tier
January 200091% Active Storage
12.52 MAF ReleaseWY 2011
Hydrology
Structural Deficit
Upper Basin Consumptive Use
The Future • Impacts of future temperature will ↑
demands & reduce stream flows
• New uses a zero sum game • Outside promises & expectations are
still a political force
• Solutions will be systemwide
Lake Powell Releases
• 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
• Controlled by the 2007 Interim Guidelines
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, drought operations reduce risk, more severe droughts require demand management (e.g., 1988-1993 & 2001-2005)
• In fact, severe droughts require very large volumes, so “trade-offs” and alternative strategies needed
• Example: Demand Management combined with a Water Bank: could limit the annual impact to Consumptive Use by spreading conservation over many years
Hydrology comparisonaverage 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/yearCC = climate change* = gage period T = paleo-hydrology based upon tree rings
Data from Reclamation’s Naturalized Flows database
Upper Basin uses incl. reservoir evap. 4.0 - 4.5
Lower Basin mainstream uses 7.5 - 7.5Lower Basin reservoir evap. 1.0 - 1.5Lower Basin tributaries 2.0 - 2.5Total Lower Basin 10.5 - 11.5
Subtotal 14.5 - 16.0Add Mexico 1.5 1.5
TOTAL 16.0 – 17.5
Current Use EstimatesMAF/ year