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-:; ~ - I1~TRODUCTIOF! Mining of the F seam at Atlantic Richfield's (ARCO) Mt. Gunnison t•line will result in a certain amount of subsidence and fracturing of over- burden units. Inflow of water into the mine may result if hydrologic connection with surface water or the limited overburden aquifers resLlts from subsidence and fracturing of the overburden. However, in operating this project, ARCO is committed to protecting valid water right interests from any negative impacts of mining on water supply. Furthermore, ARCO is committed to protecting its mining operations from the negative impacts of increased mine water inflows: It must be pointed out that any unusual water inflow into the tot. Gunnison P1ine represents a "nuisance" to the operations. Atlantic Richfield will take every precaution to insure.that water does not enter the mine needlessly. A map sho~.ving watershed areas and associated streams, reservoirs and ditches is provided in Exhibit I. The areas under which mining will occur are shown as single cross-hatched (areas tributary to the PJorth Fork), shaded (areas tributary to Minnesota Creek) and double cross- hatched (example of 50A extraction safety zone for a perennial stream). Table 1 lists the acreagzs of each basin under which mining will take place. Baseline studies indicate that flow originating within the lease area is in direct response to snovanelt and precipitation events. Streams originating primarily on the lease area, Sylvester Gulch, Lone Pine Gulch, Dry Fork of Pinnesota Creek and Lick Creek are all ephemeral. Horse Creek and South Prong of tinnesota Creek are perennial but their source originates outside the lease block at higher elevations on Mt. Gunnison. All of these streams, with the exception of Sylvester Gulch and Lone Pine Gulch, are tributary to 1innesota Lreek. Sylvester and Lone Pine Gulches are tributary to the Plortfi Fork of tfie Gunnison River. • (1)