FLOWS FOR THE FUTURE 2005 Environmental Flows Conference Texas State University – San Marcos November 1, 2005 Bob Brandes Region M Water Planning Study

Rio Grande Planning Region

Region M Counties and River Basins

Region M Projected Population

Region M Environmental Flow Issues Rio Grande Flows Are Highly Regulated andSubject to Mexico’s OperationsRio Grande Flows Are Highly Regulated and Subject to Mexico’s Operations Rio Grande Basin Is Already Over- AppropriatedRio Grande Basin Is Already Over- Appropriated Projected Demands Are Changing and Substantial Relative To Existing SuppliesProjected Demands Are Changing and Substantial Relative To Existing Supplies Strategies Reflect Primarily Utilization of Existing Surface Water Resources; No Major Surface Water DevelopmentStrategies Reflect Primarily Utilization of Existing Surface Water Resources; No Major Surface Water Development

Amistad Reservoir Falcon Reservoir Anzalduas Reservoir Elephant Butte Reservoir Major Rio Grande Mainstem Reservoirs Total Storage Capacity: ~ 8,000,000 Acre-Feet Caballo Reservoir

Rio Grande Mean Annual Flows

Mexican Treaty Tributary Reservoirs Total Storage Capacity: ~ 4,000,000 Acre-Feet Rio San Juan Reservoir Capacity: ~ 1,700,000 Acre-feet

Region M Environmental Flow Issues Rio Grande Flows Are Highly Regulated andSubject to Mexico’s OperationsRio Grande Flows Are Highly Regulated and Subject to Mexico’s Operations Rio Grande Basin Is Already Over- AppropriatedRio Grande Basin Is Already Over- Appropriated Projected Demands Are Changing and Substantial Relative To Existing SuppliesProjected Demands Are Changing and Substantial Relative To Existing Supplies Strategies Reflect Primarily Utilization of Existing Surface Water Resources; No Major Surface Water DevelopmentStrategies Reflect Primarily Utilization of Existing Surface Water Resources; No Major Surface Water Development

Region M Existing Water Rights Total Authorized Water Rights: 2,247,334 Ac-Ft/Yr

Year United States MexicoTotal 20001,087,449901,7001,989, ,067,310888,2001,955, ,056,719879,7001,936, ,048,965869,2001,918, ,041,627858,7001,900, ,034,592846,7001,881, ,024,987835,7001,860,687 Projected Firm Annual Yield Amistad-Falcon Reservoir System

Region M Environmental Flow Issues Rio Grande Basin Is Already Over- AppropriatedRio Grande Basin Is Already Over- Appropriated Rio Grande Flows Are Highly Regulated and Subject to Mexico’s OperationsRio Grande Flows Are Highly Regulated and Subject to Mexico’s Operations Projected Demands Are Changing and Substantial Relative To Existing SuppliesProjected Demands Are Changing and Substantial Relative To Existing Supplies Strategies Reflect Primarily Utilization of Existing Surface Water Resources; No Major Surface Water DevelopmentStrategies Reflect Primarily Utilization of Existing Surface Water Resources; No Major Surface Water Development

Region M Water Demands

Municipal Supply vs Demand (acre-feet/year)

Irrigation Supply vs Demand (acre-feet/year)

Historical Irrigation Demands Total Irrigation Water Use Varies According To Available Amistad-Falcon Supply and Climate

Region M Environmental Flow Issues Rio Grande Basin Is Already Over- AppropriatedRio Grande Basin Is Already Over- Appropriated Rio Grande Flows Are Highly Regulated andSubject to Mexico’s OperationsRio Grande Flows Are Highly Regulated and Subject to Mexico’s Operations Projected Demands Are Changing and Substantial Relative To Existing SuppliesProjected Demands Are Changing and Substantial Relative To Existing Supplies Strategies Reflect Primarily Utilization of Existing Surface Water Resources; No Major Surface Water DevelopmentStrategies Reflect Primarily Utilization of Existing Surface Water Resources; No Major Surface Water Development

Projected Water Supplies From Recommended Strategies Acquisition/Conversion of Water Rights 136, ,171 Brackish Groundwater Desalination 62,339 62,339 Gulf Coast Aquifer Development 49,204 49,204 Advanced Water Conservation 43,766 43,766 Non-Potable Water Reuse 38,532 38,532 Brownsville Weir and Reservoir 20,643 20,643 Potable Water Reuse 1,120 1,120 Seawater Desalination Total Additional Supply 352, ,664

Strategies With Potential Direct River Flow Impacts Acquisition/Conversion of Existing Water RightsAcquisition/Conversion of Existing Water Rights Urbanization of Irrigated FarmlandUrbanization of Irrigated Farmland Purchase of Existing Unused Water RightsPurchase of Existing Unused Water Rights Contract for Municipal Water from Irrigation DistrictContract for Municipal Water from Irrigation District Brownsville Weir and ReservoirBrownsville Weir and Reservoir Water Right Permit Issued By StateWater Right Permit Issued By State Includes Environmental Flow ProvisionsIncludes Environmental Flow Provisions

FLOWS FOR THE FUTURE 2005 Environmental Flows Conference Texas State University – San Marcos November 1, 2005 Bob Brandes Region M Water Planning Study