Rio Grande Water Summit November 17, 2005

Hydrology –U.S. Portion of the Watershed

Source in Colorado to Fort Quitman, Texas, River Length = 1,025 Kilometers Drainage area = 82,734 square kilometers 96% in U.S. // 4% in Mexico Regulated by: 1) Rio Grande Compact (1938), Colorado, New Mexico and Texas 2) Convention of 1906, U.S. and Mexico 3) Pecos River Compact(1949), New Mexico and Texas Upper Rio Grande Basin Major Reservoirs, Rio Grande 1) El Vado, 2) Heron, 3) Abiquiu, 4) Cochiti, 5) Elephant Butte, 6) Caballo Total Capacity (Spillway levels) 5,724.8 million Cubic Meters (Mcm) Major Reservoirs, Pecos 1) Santa Rosa, 2) Lake Sumner, 3) Brantley, 4) Red Bluff Total Capacity (Spillway levels) 1,086.1 Mcm Total Capacity, Upper Rio Grande Basin 6,810.9 Mcm Upper Rio Grande Basin 1906 Convention 1) Provides for annual delivery of 74.008 Mcm to Mexico at Cd. Juarez for irrigation 2) In case of extraordinary drought, reductions are made in proportion to the reductions to U.S. lands • Reductions were made in 2003/2004 • Full allocation was made in 2005 after beginning the season with a reduced allocation Rio Grande at San Marcial, NM •Gaging station located just upstream from Elephant Butte Reservoir •Source of flow mainly snowmelt runoff from mountains in Colorado and New Mexico, •March-July runoff period •Snowmelt runoff accounts for about 70% of total annual flow on average Rio Grande at San Marcial Flow Trends U/s to d/s rain Tribmap Middle / Lower Rio Grande Basin

Fort Quitman to the Gulf •Regulated by the 1944 United States-Mexico Water Treaty •Reach length, 1,844 river kilometers •Drainage area, 373,967 sq. kilometers 40% U.S., 60% Mexico Amistad/Falcon International Reservoirs Middle-Lower Rio Grande Basin

U.S. Tributaries as listed in the 1944 Treaty 1. Alamito Creek 2. Terlingua Creek 3. Pecos River 4. Devils River 5. Goodenough Spring (inundated by Amistad Reservoir – 1968) 6. San Felipe Creek 7. Pinto Creek U.S. Tributaries Storage Reservoirs only on Pecos River U.S. Tributaries, 1969-2004 Average Flows U.S. Tributaries U.S. Tributaries, Extreme Flows, 1994-2005 Alamito Creek(Period of Record 1932-2005) Min. monthly , October 2001 – 0 m3/s Min. annual, 2001 – 0.01 m3/s Terlingua Creek(Period of Record 1932-2005) Min. annual, 1994 – 0.10 m3/s Max. annual, 2004 – 5.97 m3/s Max. instantaneous – 1,310 m3/s More Extreme Flows

Pecos River (Period of Record 1967-2005) Min. daily, Aug. 4, 1998 – 1.19 m3/s Min. monthly, July 1998 – 1.53 m3/s Min. annual, 1999 – 3.27 m3/s San Felipe Creek (Period of Record 1932-2005) Max. instantaneous, Aug. 24, 1998 - 3,340 m3/s Max. daily, Aug. 24, 1998 – 464 m3/s Max. annual, 1998 – 3.97 m3/s U.S. Tributaries as Portion of Total River Flow

Portion of Total Amistad/Falcon Inflow from U.S. Tributaries 1969-1992 --- 26% 1993-2004 --- 40% Rainfall Trends, Ft. Quitman to Falcon Dam