The Central Arizona Project (CAP) and Planning for Times of Shortage

Transcription

1 The Central Arizona Project (CAP) and Planning for Times of Shortage Sharon B. Megdal, Ph.D. Director, Water Resources Research Center, The University of Arizona Elected Member, Board of Directors, CAP Hermosillo, MX May 7, 2010

2 The WRRC Mission The University of Arizona's Water Resources Research Center (WRRC) promotes understanding of critical state and regional water management and policy issues through research, community outreach and public education. The WRRC is committed to: assisting communities in water management and policy; educating teachers, students and the public about water; and encouraging scientific research on state water issues. Web site: 2

3 Arizona Water Management Surface water and groundwater managed separately by the state Colorado River water managed differently than other surface water Groundwater Management practiced in Active Management Areas (shaded areas on the map) according to the Groundwater Management Act Federal Role is limited, especially with respect to groundwater 3

4 El Proyecto de Centro-Arizona El Proyecto CAP Construcción terminado en 1993 Proyecto de Centro-Arizona COSTO - $3.6 billion de dolares CAPACIDAD - >1,900 Mm 3 LONGITUD 540 kilometros AUMENTO DE ALTURA 730 metros SIRVE 4 millones de personas y 100,000 hectáreas de agricultura Source: Central Arizona Project 4

5 CAP System Map CAP Serves Three Central Arizona Counties 5 Source: Central Arizona Project

6 El Río Colorado Aportaciones Cuenca del Río Colorado Cuenca Alta - 9,250 Mm 3 (7.5 maf) Cuenca Baja 9,250 Mm 3 (7.5 maf) ************ California 5,425 Mm 3 (4.4 maf) Arizona 3,455 Mm 3 (2.8 maf) (CAP >1,900 Mm 3 (1.5 maf)) Nevada 370 Mm 3 (0.3 maf) Arizona (Cuenca Alta) 62 Mm 3 (0.05 maf) México - 1,850 Mm 3 (1.5 maf) Source: Central Arizona Project 6

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8 Colorado River was Allocated based on a wet period in history: Colorado River at Lees Ferry Gaging Station, Arizona, Water Year 1906 to

9 Colorado River Drought has been the driest 10-year period in the 100-year historical record (WY 2008 and WY 2009 data are estimated) Tree-ring reconstructions show more severe droughts have occurred over the past 1200 years (e.g., drought in the mid 1100s) Forecasted 2010 April through July runoff is 66% of average as of April 15 Not unusual to have a few years of above average inflow during longer-term droughts (e.g., the 1950s) Source: U.S. Bureau of Reclamation9

10 Lake Mead: The storage reservoir for the Lower Colorado River Basin 10

11 Low Flows due to drought and climate change a key concern to CAP due to its Junior Priority The CAP low priority means that CAP is particularly vulnerable to shortages. Its allocation will be reduced to zero before California experiences shortage. In order to alleviate the harsh impacts of this junior status, Arizona worked with the other seven basin states to develop shortage sharing guidelines, which were adopted by the U.S. Secretary of the Interior in

12 Shortage Sharing Guidelines were developed that consider Lake Mead and Lake Powell Storage Levels Information below as of April 25, 2010 Source: U.S. Bureau of Reclamation12

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14 Shortage Sharing Guidelines Stage 1 shortages are mathematically possible as soon as 2012, but not very likely; the USBR 24- month study does not show a shortage occurring in 2012 No shortage that would impact CAP Cities and Indians is expected before mid-2020s Guidelines assist AZ planning efforts According to CAP staff, negotiations are underway with Mexico to determine the nature of any shortage sharing between Mexico and U.S. water users. 14

15 What is CAP doing to prepare for Climate Change? Planning for potential shortages, other impacts Participating in the modeling of river runoff scenarios Evaluating alternative options Adaptive management, river augmentation, conservation (Yuma Desalting Plant and Drop 2 Reservoir) Storing excess water underground today for use during shortages Arizona Water Banking Authority has built up significant storage in Central Arizona to use during times of shortage to CAP M&I customers. 15

16 CAP Water Storage Facilities 16

17 What is being done to improve the Colorado River watershed climate models? Participating in regional and national research to improve the accuracy of climate models; downscaling global models to improve their utility for the Colorado River basin Developing new methods to use climate models to generate stream runoff projections for use in Colorado River system models Using tree-ring data to develop a stream flow record for the past 1,240 years to capture a wider range of runoff variability 17

18 How much does evaporation affect CAP and will that be impacted by climate change? Current evaporation rate is less than 5% of CAP deliveries (less than losses in municipal delivery systems which are about 10%) Even a 20% increase in temperature due to climate change would result in < 6% total evaporation Recharge site evaporation is less than three percent Recovery planning is important 18

19 Is the glass half full or half empty? There are many issues to be worked on and many people working on them! 19

20 Issues and Challenges Drought, Climate Change Growth and the need for additional supplies Water and Energy Water management outside the Active Management Areas (AMAs), including water quantity assessments Water Quality Use of effluent for potable and other water needs the next major new water source Access to and utilization of renewable supplies Transboundary water issues The surface water/groundwater interface Riparian areas and other environmental considerations related to water Conservation Programs Recovery of Stored Water Approaches to replenishment Water cost/pricing Water Planning 20

21 Gracias! Preguntas? Thanks to staff at the Central Arizona Project for information and graphics contained in this presentation. 21