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~: - ! . due to the underdesigned spillway and reservoir leakage, no more than 500 acrd-fee*_ can he stored in the reservoir. • W d l d i th l t t " iti d" a er s orage an re ease ur ng . e cr ca nee period (July, August, September) varies markedly between wet and dry years. The variation in reservoir release is reflected in the data from the Lovrer Dry Fork gaging station summarized in Table 2. Water year 1977 was a dry year so little water was stored for release during the "critical need" period. The percentage of capturable seater (release during July, .4u gust and September divided by annual water yield) varies from approximately 49% to 56% for the relatively wet seater years of 1978, 1979 and 1930. Since water yields from the lease..biock and flows from Horse Creek, South Prong and Deep Creek Ditch are nil or very low during the months of August and September, it is water stored in 19innesota and Beaver Reservoirs that provides the bulk of the irriga- tion water during the critical need periods. Fortunately, the reser- voirs are off the mining area and can not be impacted by mine subsidence. Thus, the reservoirs provide a buffer that will allow Atlantic Richfield to mitigate any impacts of subsidence on • streamflows from the lease block. The Dry Fork channel will be protected by limited extraction in order to prevent any damage from subsidence to the source of water for t4innesota Reservoir. This protection will be accomplished by creating a safety zone under the channel, t4ining in this safety zone will leave 50% of the coal in place. The limited extraction should prevent any loss from Dry Fork channel resulting from mine subsidence because subsidence will not occur in the protected zone. liosvever, in the event our predictions and expec- tations are wrong, Atlantic Richfield has developed mitigative plans to correct any adverse impacts on streainflow resulting from mining. These mitigative plans are applicable to all streams on the lease block including the Dry Fork channel. The ~.vorse case scenario would be if there is a total loss of water • from the Dry fork channel during the peak snovnnelt runoff period.