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I I I I I I I I I I I I I I I I I I I 2. PRESENT WATER RESOURCES CONDITIONS STREAMFLOWS Streamflows vary appreci ab ly throughout the Regi on, both in quanti ty and seasonal distribution. Pertinent hydrologic characteristics of each of the major streams in the thirteen WAU's are listed in Table 2, and the variation of mean monthly flows for several selected locations within the Region are illustrated in Figure 3. Streamflow gages used in these analyses are iden- tified in Figure 4. Colorado The average quantity of surface runoff and precipitation entering the Rio Grande Basin of Colorado is on the order of 2.8 million acre-feet per year [7,8], with the variation from year to year depending mainly on snowmelt from the San Juan and Sangre de Cristo Mountains. Surface water diversions, primarily for irrigation, and evapotranspiration losses from both crops and nonbeneficial vegetation reduce the average annual discharge of the Rio Grande leaving Colorado to approximately 300,000 acre-feet [7,8,9]. With this average level of flow in the River over the past forty years, deliveries of water by Colorado to New Mexico under the provisions of the Rio Grande Compact have been deficient and are reported to have been in debit in 19~ by an accrued amount of 705,000 acre-feet [10]. SD 1-7'1,1..<0 I ,., The seasonal variation of flow in the Rio Grande in Colorado near the lower end of WAU 130100 is illustrated in Figure 3. Mean monthly flows are highest during May and June as a direct result of snowmelt, and typically, they are lowest during the late summer months when runoff is minimal and when river water is being diverted for irrigation in the San Luis Valley. New Mexico Streamflow conditions in the New Mexico segment of the Rio Grande vary as a result of seasonal climatic influences, reservoir operations, and irri- gation diversions. These variations are evident in the mean monthly flow 0106 8