| OCR Text |
Show - 16 - The Upper and Lower Santa Cruz Basins and the Avra-Altar Basin (Basins 4, 2 and 3, pi. 1) have been studied (S. F. Turner and others, 1943) in some detail and figures for safe annual yield of these basins are quoted from the report. The safe annual yield of Basin 3 is included in the figure for Basin 2. The problem of safe annual yield in the Lower San Simon-Gila River Basin and in the Duncan Basin (Basins 8 and 9, pi. 1) is involved with legal problems related to prior rights to water in the Gila River (S. F. Turner and others, 1946; L. C. Halpenny and others, 1946). This complication precludes the possibility of establishing a figure for safe annual yield on hydrologic grounds. The other basins included in the overall Central Arizona Project are too imperfectly known geologically and hydro-logically to permit estimating their safe annual yield. Estimates of the safe annual yield and average annual overdraft in Basins 1,2,3, and 4 are given in the table below. Safe Average annual Basin annual yield overdraft 1941-50 1. Salt River Valley 500,000 - 1.000,000 265,000 - 765,000 2. and 3. Lower Santa Cruz and Avra-Altar 135,000 520,000 Sub-total - Maricopa- IMnal area 635,000 - 1,135,000 785,000 - 1,285,000 4. Upper Santa Cruz 80,000 65,000 The overdraft has greatly increased during recent years |
