The Colorado River Big Issues for a “Not-so-big” River

Eric Kuhn, General Manager

State of the Gunnison RiversMontrose, Colorado - May 31, 2017

Presenter

Presentation Notes

It’s time to talk about the big picture…Downstream obligations, basin statistics

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

Presenter

Presentation Notes

The primary reason for Lake Mead’s decline since 2000 is not the ongoing drought, but rather the “structural deficit” that exists in the Lower Basin. No Lower Basin state is exceeding its apportionment. An 8.23 MAF annual release from Lake Powell is nominally sufficient to cover the 7.5 MAF apportioned to the Lower Basin states as well as one-half of the 1.5 MAF Mexican Treaty obligation. But losses due to evaporation in Lake Mead and evapotranspiration downstream of Glen Canyon Dam exceed average gains from side inflows. And the Lower Basin must also provide its half of the Mexican Treaty obligation. The net result is that the Lower Basin operates at a deficit of about 1.2 MAF per year, which causes a drop of about 12 feet annually in Lake Mead when 8.23 MAF is released from Lake Powell. Only larger, equalization releases from Lake Powell—which are projected to occur less frequently in the future due to climate change—can prevent the annual decline of water levels in Lake Mead under present conditions.