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Water Resources Issues in the Lower Rio Grande. June 3, 2005 J. Phillip King, P.E. Assc. Professor/Assc. Dept. Head Dept. of Civil Engineering, NMSU Consultant, EBID. Major LRG Water Issues. Drought and Project Water Allocation – Reclamation, EBID, El Paso #1, Mexico
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Water Resources Issuesin the Lower Rio Grande June 3, 2005 J. Phillip King, P.E. Assc. Professor/Assc. Dept. Head Dept. of Civil Engineering, NMSU Consultant, EBID
Major LRG Water Issues • Drought and Project Water Allocation – Reclamation, EBID, El Paso #1, Mexico • Active Water Resource Management (AWRM) alternative administration regulations – OSE, Lower Rio Grande Water Users Organization (LRGWUO) • Conversion of surface water to non – agricultural uses in LRG – EBID, Las Cruces, Doña Ana MDWCA, OSE
Caballo Release ET Precip Conveyance System Diversion Bypass (spill) Delivery Irrigated Land ET Precip Atmosphere Rio Grande Pumping Deep Percolation Seepage Imported Water Exported Water Groundwater Seepage Exfiltration M&I Users Bypass (spill) Pumping Drainage Deep Perc. Drain Flows Discharges Return Pumping Deep Percolation ET Precip Non-irrigated Land Storm Flow Rio Grande at El Paso Surface Water-Groundwater Interaction in the LRG
Water Use by Sector in LRG 97 percent of LRG water use is irrigation or public water systems
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 • Construction largely completed by 1917; drainage system built in 1920s • Operated as a single irrigation system by Bureau of Reclamation • City of El Paso began treating surface water in 1940s • Districts paid off construction costs in late 1970s
Current Project Water Allocation • BOR allocates water to US districts and Mexico • Based on water available for release storage and actual river efficiency • Mexico gets their water first, and the remainder is divided between EBID and EP#1 proportionately (57%/43%) • Districts allot water to farmers based on BOR allocation and system conveyance efficiency
Drought Response • Conjunctive management of surface water and groundwater • Robust river-connected aquifer used for agriculture, M&I, domestic use • Short surface water supplies prompt increased groundwater withdrawals • Groundwater withdrawals affect river efficiency
Motivation for AWRM • Manage surface water and groundwater intelligently to maximize beneficial use in New Mexico • Maintain hydrologic health of the LRG • Protect senior water rights from impairment in the absence of a completed adjudication • Protect downstream users in Texas and Mexico from overuse in LRG • Provide mechanisms for out-of-priority users to offset impacts on senior and downstream water users
Complications • Rio Grande Operating Agreement • Project authority over surface water, OSE authority over groundwater • Lack of clarity in relationship between surface water and groundwater rights • Junior basic necessities
Current Status of AWRM • State-wide regulations finalized • Metering order issued for all groundwater diversions in LRG except single domestic wells • State is developing draft basin-specific regulations for LRG to be released for review by LRGWUO in May - delayed 2 months • LRGWUO directed technical committee to develop alternative administrative plan
Foundations for Special Water Users Associations • Developed by EBID, City of Las Cruces, and the State Engineer • EBID Policy 2003-GA8, approved November 19, 2003 • 73-10-48 NMSA
SWUAs • Allow entity to use surface water for M&I and other uses within District boundaries • Ownership of Project Water rights • Lease of Project Water rights • Transfer of Project Water
SWUA Details • Assessed as EBID constituents • Share pro rata in shortages • Surface water rights maintain EBID’s 1906 priority date • SWUA must lease all of the water from a parcel; land must be fallowed • Special Combined Unit: Small tracts (<2 acres) can be consolidated and treated as farm tract for ordering and billing • Maintained as Ag use until demand for direct M&I use develops
Total Allotment Agricultural Users Agricultural Water Used Conservation Pool Existing System of Annual Water Transfers
Structure for Transfers of Water to Special Water Users Associations Total Allotment Leases: Parties Negotiate Price Agricultural Users SWUA Agricultural Water Used Municipal Water (SWTP) Agricultural Pool Conservation Pool: Municipal Pool
Who Can Form SWUAs? • Municipalities • Counties • State Universities • Member-owned community systems • Public utilities • Interstate Stream Commission
Relationship of SWUAs to AWRM • SWUAs provide an alternative to strict priority administration • SWUAs allow junior users to move up in seniority/priority • Common priority date among EBID SWUAs and irrigators create pro rata sharing of shortages • Market-driven process