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• • TABLE 17-29 ICOntinuedl Probable Hydrologic Consequences Analysis Results Significance duration of the impact will be long term seeps degrade the Dry Creek water 7. (Continued) (<20 yeaf5). Spoil discharge to Sage Creek quality will result in a 2 percent increase in to such an extent that Che additional TDS at the confluence of Sage Creek and spoil discharge would be diluting the the 009 tributary. The extent of any TDS measurable TDS change will be quite levels. The stock use pot en[ial of the limited as diluting effeccs will rapidly wafer has remained unchanged. Thus, the diminish the increase. The duration of significance of Che spoil disclfarye to the minimal impact will be long term (<20 Dry Creek ie minimal and precludes no yeafs). existing or potential uses of the water. There are no irrigation Farming practices iR d Close Vicinity Co the 009 tributary to Sage Creek and trie water use as stock water will remain unchanged. The significance of the spoil discharge is negligible. Surface Water 1. Effects o£ mining on the local geomorphology. Mining will di scucb 19 percent of the 005 Basin, and 50 percent of the 006 Basin. Little to no changes in overall basin parameters (shape, size, watershed elopes, etc). Minor changes 12-3 percent) in eubwatershed slopes in upper portions of each basin due to reconstructed landscape. Minor changes in overall drainage density will occur, but limited to upper portions of each basin. Reconstructed postmining channels will be designed to have comparable or Lower gradients than prior [o mining. Impacts to geomorphology will be long- term, but wrll result in minimal and insignificant impacts. Impacts will be limited to upper portions of each basin. Reconstruction of drainage channels using adequate design criteria will minimize impacts to fluvial system. Permanent impoundments (005-006) will be properly designed, and will also minimize impacts to the Fluvial system. 2. Effects of sediment ponds on channel characteristics and downstream uses. Channel reaches below the sediment ponds will become incised, but will eventually adjust [o stability as vegetation encroaches and geometries adjust to changes in discharge frequencies, magnitudes, and sediment. Any present or potential use of waters for flood irrigating small AVF's will not be jeopardized by long-term increased chemical loading. Impacts to channel characteristics will be long-term, but of minimal significance. Channels below permanent impoundments will adjust naturally to changes in pond discharge frequencies and magnitudes. Impacts to dOwnst ream users will be long-term, but of minimal significance because: 1) increases in chemical loading will not 81 Revised O~I01