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I: ", " . ,. " '\. 'I i' I, " I , " 'I 'I I, ,_o,,.,nn/~ _ ,_________n____ ". :U.tl_U ~-_ ___ __ - _ __ -____ :.~~-=~------- 1 -12- the right abutment the ground surface rises. The result is that the overburden increases rapidly in thickness toward the south to more than 200 feet. This overburden consists primarily of river sand and gravel with a mantle of dune sand. Beyond the point (Elevation 4450) which forms the top of the right abutment, the land surface reaches an elevation of 4470, then drops down again to the south to Bijou Creek at elevation 4425. At tbis point Bijou Creek is 1"oughly parallel to the South Platte River. Beyond the Bijou, to the south, tbe land rises gently and continuously to the south. The dcep bedrock depression south of the Narrows site has accumulated a large volume of permeable sand and gravel containing ground water which is readily accessible to wells. Because the sediments arc highly pervious and the supply of water is large, many irrigation wells have been drilled. Correlation of water well data and dum site test holes indicates that the water table in the area is inclined northward fro~ Bijou Creek toward the South Platte River. It appears that Bijou Creek loses water to the north and that the water table is presently tributary to the South Platte by means of seeps along the bedrock overburden con- tact on the south slopes of the river channel. A local factor in the high water table on the right abutment is the Bijou No. 2 Resel'voir which leaks badly and contributes to the water table. The construction of a dam at Narrows and a reservoir with a water level high above the bedrock contact at the south side of the river would impose conditions whicb would tend to partially re- verse or turn the present ground water gradient and shift it to a stronger downstream component beneath the right abutment of the , ...r.... ... ~-'