Historical Water Management in the Lower Rio Grande

1. Historical Water Management in the Lower Rio Grande Lower Rio Grande Water Users Organization August 19, 2005 J. Phillip King, P.E., Ph.D.

2. The Rio Grande Compact of 1938 • Researched and negotiated among Colorado, New Mexico, and Texas between 1925 and 1938 • Explicitly divided the surface water of the Rio Grande among the states, and providing for delivery to Mexico • Sliding scale dependent on supply • Capped depletion in upstream states • Accounting rules and obligations allow flexibility within each state

3. Otowi Compact NM Compact TX Compact Geography

4. The Rio Grande Project • Water rights appropriated January 23, 1906 • 90,640 water-righted acres in Elephant Butte Irrigation District (EBID) in New Mexico • 69,010 water-righted acres in El Paso County Water Improvement District No. 1 (EPCWID) in Texas • 60,000 acre-feet of water for the Republic of Mexico by the Treaty of 1906 • Operated as a single irrigation system by Bureau of Reclamation

5. Project History in a Nutshell

6. Project Terminology • Release – Flow of water from Caballo Dam • Diversion – Removal of water at Project structures – Percha, Leasburg, Mesilla, American, International Dams • Delivery – Flow from District canal to farm or non-agricultural use • Return Flow – Drains, operational spills, storm flows, WWTP discharge • River Efficiency – Diversion/Release

7. Current Project Allocation Procedure • Usable water in storage determined • Total diversion determined based on actual river efficiency • Mexico allocation by formula • Remaining diversion split between EBID (57 %) and EPCWID (43 %)

8. D2 – River Efficiency Relationship

9. Caballo Release ET Precip Conveyance System Diversion Bypass (spill) Delivery Seepage Storm Flow Irrigated Land ET Precip Atmosphere Rio Grande Pumping Deep Percolation Imported Water Exported Water Groundwater Seepage Exfiltration Storm M&I Users Bypass (spill) Pumping Drainage Deep Perc. Drain Flows Discharges Return Pumping Deep Percolation ET Precip Storm Non-irrigated Land Storm Flow Rio Grande at El Paso District Hydrology

10. The LRG Regional Water Plan • Prepared by the LRGWUO • Recognizes the hydrologic connection between Mesilla and Rincon aquifer systems and the Rio Grande • Recognizes the need to “keep the river whole” • Recognizes need to clarify obligation to Texas • Ongoing negotiations among EBID, EPCWID, and Bureau of Reclamation to clarify obligation to Texas

11. Active Water Resource Management • State administering groundwater in the absence of a completed adjudication • State’s standard issue tool is priority administration • Local users have the ability to develop alternative administration rules • Advantages: • Future new uses will rely on surface water • Current junior uses can use surface water rights to move up in priority • Intelligent conjunctive management of surface water and groundwater is possible • Requires cooperation among LRGWUO members and State

12. Old School • Adversarial • Egos, conflicting agendas, cloak-and-dagger games clog the process • Time and money consuming • Destructive • Bad for all concerned

13. A New Paradigm • Principled negotiation • Common ground kept in mind • Cool heads prevail • Accurate, objective data analysis • Recognize obligations

14. From the Rio Grande Joint Investigation: “… The cordial willingness with which the official representatives of Colorado, New Mexico, and Texas entered into the undertaking exemplified constructive statesmanship… Each of these States is vitally concerned with its own welfare, yet in the Rio Grande Joint Investigation each recognized its obligation to its sister States; each accepted the principle that an equitable adjustment of conflicting interests in the waters of the river is imperative.” Frank Adams, Harlan H. Barrows Chairman, Consulting Board, February 1938