1. Drought on the Colorado River System: Impacts and Response
Bill Steele
Area Manager, Southern California Area Office
Urban Water Institute Annual Water Conference in San Diego, CA
August 25, 2016

2. Topics Colorado River Basin Overview
Lower Colorado River Water Master Role
Drought and Drought Impacts
Drought Response Activities
Summary
Key points:
Here’s overview of today’s presentation. Topics include…
A brief overview of the Colorado River Basin
Reclamation’s role was water master of the Lower Colorado River
The current drought in the Colorado River Basin and impacts to system storage
Drought response activities
Summary 2

3. Overview of the Colorado River Basin
16.5 million acre-feet (maf) allocated annually
13 to 14.5 maf of consumptive use annually
60 maf of storage
14.8 maf average annual “natural” inflow into Lake Powell over past 110 years
Inflows are highly variable year-to-year
Key points:
System storage in the Colorado River Basin totals about 60 maf (4 times the average annual inflow)
This large storage capacity creates a buffer to this year-to-year hydrologic variability by allowing us to store additional water during wet years and to use water from storage to meet water deliveries during dry years
The system is working exactly as designed; to date, a Lower Basin Shortage has never been determined
The Basin’s two largest reservoirs, Lake Powell and Lake Mead, combine for about 50 maf of storage, or 83 percent of the total system storage capacity
Additional notes:
At the time when the 1922 Colorado River Compact was completed and the allocations for Upper Basin and Lower Basin were developed, the average annual natural flow in the Upper Basin was about 18.0 maf.
At the time when the 1944 U.S.-Mexico Water Treaty was completed, the average annual natural flow in the Upper Basin was about 16.3 maf.
Through water year 2015, the average annual natural inflow in the Upper Basin is about 14.8 maf.
We can see how, over time, the average annual inflow has decreased, the system has been operated on an increasingly tight budget, and it now appears like the Colorado River system is over-allocated.
This trend in decreased water supply, coupled with increased water demand, emphasizes for both countries to proactively work together to reduce the strain of this tighting water budget. 3 3

4. Natural Flow Colorado River at Lees Ferry Gaging Station, Arizona Water Year 1906 to 2016
Key Points:
This chart displays the natural flow at Lees Ferry, equivalent to the total inflow in the Upper Basin, approximately 90% of the total inflow in the basin.
The chart includes annual inflow (blue bars), a 10-year running average (grey line), and a moving long-term average (black line).
Inflows are highly variable from year-to-year
Some statistics:
111-year ( ) historical average is approximately 14.8 maf
was the 4th driest 2-year period ( was the driest)
Period from was the lowest 10-year average inflow—there were two years with above average inflow during the period
Period from was the lowest 12-year average inflow, but note there were a couple of good years in the period
Period from is the lowest 16-year average inflow (at 12.4 maf, or 83% of the long-term average of 14.8 maf) 4 4

5. Lower Colorado River Water Master Role
Boulder Canyon Project Act of established the Secretary of the Interior as Water Master of the Lower Colorado River
Develop Annual Operating Plan for Colorado River Reservoirs
Administer water contracts
Approve U.S. water orders
Schedule water releases from Hoover, Davis, and Parker Dams
Account for all water use
Key Points:
A unique aspect of the Lower Colorado is that the Secretary of Interior is Water Master, and performs a role similar to state engineers on other river systems in the west, as established in the 1928 BCPA.
The Water Master role is carried out by the Lower Colorado Region on behalf of the Secretary.
Core functions of the Water Master role include:
Develop the Annual Operating Plan for Colorado River Reservoirs
Administer water contracts
Approve water orders for U.S. contractors
Entitlement holders have permanent Colorado River water delivery contracts (essentially no charge for the delivery of water)
Schedule water releases from Hoover, Davis, and Parker Dams
Including real-time data collection on river flows and diversions
Account for all water use and verify conservation programs 5

6. Lower Colorado River Management Objectives
Provide flood control and river regulation
Meet water orders
Generate hydropower
Implement LCR Multi-Species Conservation Program
Support recreational opportunities
Key Points:
Lower Colorado River Management Objectives
Provide flood control and river regulation
Provide water supply to help meet water orders in the lower basin and Mexico
Generate hydropower
Implement LCR Multi-Species Conservation Program (which includes habitat enhancement and recovery of endangered species through MSCP)
Support recreational opportunities 6 6

7. State of the System (Water Years 1999-2016)1,2
Key Points:
Since 2000, the Colorado River Basin has been in the midst of an unprecedented drought.
The long-term average (represented by the white line) is 14.8 maf.
The current period from 2000 through 2015 average is 12.4 maf (represented by the orange line).
This is the driest 16-year period in the 100+ year historic record.
This is comparable to the driest 16-year period in the reconstructed 1,200-year paleo-record of 12.1 maf (represented by the green line).
During this 16-year period, only 3 years (2005, 2008, and 2011) experienced above average inflow.
Luckily, the system was essentially full at the start of the drought.
System storage declined from about 95% of capacity in 2000 to about 50% of capacity by 2005.
Since then, the system has maintained about ½ of capacity, but there has only been one year (2011) with significant inflow since 2000. 7 7

8. 8 Key points: As a result of 16 years of unprecedented drought…
In July 2016, Lake Mead declined to its lowest elevation since it initial filled in the 1930s (elevation 1,071.6 feet, or 36% of capacity on July 1).
Lake Mead’s elevation has declined approximately 140 feet since the start of the drought (the end of water year 1999) when it was about 95% of capacity.
This is a decline from elevation 1,211 feet on September 30, 1999 to elevation 1,072 feet in July 2016. 8

9. Drought Response Activities
2007 Interim Guidelines
Minutes to Mexico Water Treaty
Lower Basin Drought Contingency Planning
Drought Response Activities
Key Points:
In the Colorado River Basin, the U.S. is undertaking proactive voluntary actions to increase reservoir elevations at Lake Powell and Lake Mead to reduce the probability of reaching critical reservoir elevations.
Responses include:
The 2007 Interim Guidelines, which outline the coordinated operations of Lake Powell and Lake Mead and shortage criteria for the Lower Basin.
Recent binational cooperation through Minutes 318 and 319 of the 1944 U.S.-Mexico Water Treaty.
Phases 1 and 2 of the Pilot System Conservation Program.
Lower Basin drought contingency planning such as the creation of voluntary protection volumes for Lake Mead through a 2014 MOU for Lower Basin Pilot Drought Response Actions.
Pilot System Conservation Program 9 9

10. Lake Mead – Key Elevations1,2
1,229 ft
27.6 maf )
Flood Control or Surplus Conditions
1,145 ft
17.1 maf
Normal or ICS Surplus Conditions
1,075 ft
9.6 maf
9.5 maf*
36% of Live Capacity
1,074 ft*
Level 1 Shortage Conditions
U.S. Lower Basin Shortage = 333 kaf
Mexico Reduction = 50 kaf
1,050 ft
7.7 maf
Level 2 Shortage Conditions
U.S. Lower Basin Shortage = 417 kaf
Mexico Reduction = 70 kaf
Key points:
This teacup diagram shows more visually Lake Mead’s operating conditions under the 2007 Interim Guidelines and the key elevation triggers for each condition.
The diagram also notes the U.S. Lower Basin shortage volumes, under the three shortage levels, based on the 2007 Interim Guidelines.
Level 1: 333 kaf total = Arizona 320 kaf and Nevada 13 kaf
Level 2: 417 kaf total = Arizona 400 kaf and Nevada 17 kaf
Level 3: 500 kaf total = Arizona 480 kaf and Nevada 20 kaf
It could be noted that the 2007 Guidelines call for additional consultation with the Secretary if Lake Mead elevations are projected to decline below elevation 1,025 feet.
The diagram also shows Mexico reductions based on Minute 319, in place for an interim period from , with reductions of 50 kaf, 70 kaf, and 125 kaf, respectively.
1,025 ft
6.0 maf
Level 3 Shortage Conditions
U.S. Lower Basin Shortage = 500 kaf
Mexico Reduction = 125 kaf
1,000 ft
4.5 maf
895 ft
0.0 maf
Dead Pool
Not to scale
Dead Pool Storage 2.5 maf
*As of August 10, 2016
1 U.S. Lower Basin shortage volumes based on the 2007 Interim Guidelines (in place ).
2 Mexico reductions based on Minute 319 (in place ). 10 10

11. Lower Basin Surplus & Shortage through 2026
Key Points:
Looking ahead, based on projections from Reclamation modeling, there is about a 55% chance of Lower Basin shortage as early as 2018 and approximately 60% from 2019 through 2026.
These projections were developed using Reclamation’s Colorado River Simulation System (CRSS) and the observed Natural Flow hydrology from 1906 through 2012.
1 The projections for 2017 are based on 30 simulations of December 31, 2016 conditions from the Mid-term Probabilistic Operations Model (MTOM).
2 For the period from , each of the 30 projected initial conditions from MTOM were coupled with 107 hydrologic inflow sequences,
based on resampling of the observed natural flow record from ,
for a total of 3,210 traces analyzed in the Colorado River Simulation System
(CRSS). 11 11

12. Drought Response Activities
Basin-wide Pilot System Conservation Program
Funders:
Reclamation, CAWCD, SNWA, MWD, and Denver Water
Initial phase provided $11 million for voluntary pilot projects that create system water
System conservation agreements were implemented in both basins
Approximately 65 kaf of water will be conserved under the initial phase of the program
The program has been extended in 2016
Key points:
Basin-wide Pilot System Conservation Program
Funders: Reclamation, CAWCD, SNWA, MWD, and Denver Water
Provides $11 million for voluntary pilot projects that create system water
System conservation agreements were implemented in both basins
Approximately 65 kaf of water will be conserved
The program has been extended in 2016 12

13. Drought Response Activities
Lower Basin MOU for Pilot Drought Response Actions
Participants:
CAWCD, MWD, SNWA, Lower Basin States, and Reclamation
Goal:
Generate 740,000 acre-feet of water to benefit Lake Mead elevation
Goal:
Generate 1.5 to 3.0 maf of water to benefit Lake Mead elevation
Key points:
Lower Basin MOU for Pilot Drought Response Actions
Participants: CAWCD, MWD, SNWA, Lower Basin States, and Reclamation
Goal: Generate 740,000 acre-feet of water to benefit Lake Mead elevation, and up to 3 maf by 2019
The U.S. has committed $8.6M in FY 2015 and $11.5M in FY2016 to plan and begin implementing actions to reduce losses in the lower Colorado River system to meet its 50,000 acre-ft commitment by 2017 13

14. Projected Future Colorado River Basin Water Supply and Demand
Key Points:
Reclamation and its stakeholders, through the 2012 CR Basin Study, recognize the uncertainty moving into the future and the projected imbalance in water supply and demand
Side notes:
The average imbalance is 3.2 maf by 2060
This imbalance may be more or less depending on the nature of the particular supply and demand scenario
While the period from was the driest 16-year period in over years of record keeping, we were fortunate to start the drought in 2000 with nearly full system conditions
Climate models show increased variability in the future which may include longer, more extreme dry and wet periods than previously observed
As such, a future hydrology that includes continued drought under a changing climate may lead us to new operational challenges, and the need for innovative, collaborative solutions 14 14

15. Summary
The Colorado River Basin is experiencing an unprecedented drought
The chance of reaching critical reservoir elevations at Lake Mead continues to increase
Safeguarding our shared water supply is critical to all of us
Cooperation and collaboration will be the key to finding sustainable solutions and addressing current and future challenges

16. For further information: 16