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• relatively minor quantities of water work downward until they reach the erosional boundary between the gravel and the underlying consolidated sediments which are less permeable than the terrace gravel. Much of this groundwater then follows the gradient of this interface until it is released along the sides of the terraces as springs or seeps. One such seep of this kind is located at the extreme headwaters region of the North Fork of Bolton Draw. Water from this spring has been collected in a small pond and is used for stock water. The only other potential groundwater source in the vicinity, is the recent surficial deposits occuring in the downstream reaches of. the major drainage courses. Bolton Draw is one of these major drainage courses, and is the one that drains the proposed mine area. The unconsolidated deposits (i.e., soil, silt, colluvium, alluvium) have been mapped throughout the North Fork of Bolton Draw down into the main Bolton Draw drainage. A map of these unconsolidated deposits • is shown on Exhibit Surface Water Systems. Both the present and the proposed mining areas lie within the Bolton Draw watershed which ultimately drains into the Canadian River to the northeast. Bolton Draw drains an area of approximately 10.6 square miles. This drainage area is plotted on Plate 4 as the total area contained in Zones I through v (see Willard Owens report at the end of this Appendix). Zone V is the area presently disturbed under the existing Federal Lease No. C-27931. A fraction of Zone IV will be disturbed under the proposed mining operation for Federal Lease No. C-30168. Bolton Draw and the other similar drainages in the vicinity receive their water from snowmelt and precipitation events. Due to the sporatic nature of precipitation (falling as rain) during the year, the major flows in the draw occur during spring runoff • from snowmelt. -6-