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Qtl is Trout Creek's active alluvial floodplain. Qtl is hydrologically connected to Trout Creek. Qtl contributes baseflow to Trout Creek during low-flow periods, and is recharged by Trout Creek during the rest of the year. Qt2 is older than Qtl and consists of alluvial terrace deposits. Qt2 contains a perched aquifer that overlies bedrock. The bedrock hydrologically separates Qt2 from Qtl. Any dischazge from Qt2 eventually reaches Trout Creek via seeps along the bedrock that crops out along the creek. Qt2 is recharged by infiltrating meteoric waters. The operator calculated the mean annual water yield of Trout Creek at a point immediately downstream of the mine site as 37,500 acre-feet/year, indicating that an ample supply of water is available for flood irrigation purposes. Irrigation is conducted in the Trout Creek AVF. Ditches and flood irrigated land are shown on Map 4.6-16 of the PAP. Sub-irrigation potential exists on the Qtl terrace of Trout Creek. Species of vegetation on the Qtl terrace which are indicative ofsub-irrigated conditions are delineated on Map 2.4-1 of the PAP. Ground water levels observed in the alluvium along Trout Creek also indicate that sub-irrigation occurs. Depths to water ranging from one to six feet have been observed during monitoring. The operator has presented land use information on Exhibit 2.9-1 of the PAP. Land use along the Trout Creek AVF consists of cropland, pasture, and shrub and brush rangeland. Irrigated native hay is produced by several farms in the vicinity of the permit area. The operator has also assessed the significance of the hay production on Trout Creek AVF portions of the individual farming units. This is expressed in terms of "percent of total hay production" for each individual farm". This information indicates that the hay production on the Trout Creek AVF is significant to the farming units in the vicinity of the mine. Physical Disruption of AVF by Mining Mining operations did not extend into the Trout Creek alluvial valley floor; consequently, the AVF was not physically disturbed. Dewatering of Trout Creek Alluvium An analysis done by the Division showed that a maximum drawdown of 1.6 feet could have occurred where Trout Creek alluvium is nearest the West Ridge box cut. Data from the alluvial wells did not indicate that drawdown to this degree had occurred; only a seasonal fluctuation in water level was apparent. The slight reduction in sub-irrigation potential was predicted in the imgated cropland near the West Ridge mining area due to temporary alluvial aquifer drawdown. This " PAP, Section 2.9.3.2 and Exhibit 3.7-I) C-1980-001 Permit Renewal 5 Findings Page 31 of 33 Pages