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- 7 - ~• The mine workings are situated within a geologic structure identifiei as a graben. This graben is bounded on both sides by faults. Mining of the coal is not possible beyond the faults because of the displacement of [he coal seams. One set of entries has encountered the fault on the south side of the graben. This fault produced water for a short period until it was dewatered and it did not interfere with mining operations. It is surmised the fault will be en- countered again by the mine and will likely produce water. There also is a slight possibility that the predicted ground water zone of saturation will be encountered during this permit term. In order [o monitor the effect of the operation on ground water resources and to assist in the prediction of hydro- logic impacts of future permit terms, a stipulation was included in the pre- ferred alternatives section. f Alluvial Valley Floors. An alluvial ground water aquifer has been identified along East Salt Creek. Monitoring wells established in the alluviu® indicated that alluvial water levels fluctuate seasonally in response to water flow is East Salt Creek. .Data collected by the"applicant from the Salt Creek-alluvial aquifer thus far Sndicates a carbonate-sulfate water type, similar to the chemistry of the surface water in this area. No significant adverse affects on ground water are anticipated by this operation, but a stipulation was included in the preferred alternatives section to confirm this conclusion. No farming activities ioiil be physically affected by the above surface im- _ :' pacts: The'land`use`type=which will be directly affected is rangeland. The conclusion is that the surface disturbance related to the operation is limited in extent and will not directly affect any farming activities in the alluvial valley floor. •._-- ---_ =_ .: An area of irrigated cropland is located on the East Salt Creek alluvial val- ley floor approximately 1/2 mile downstream of McClane Canyon. irrigation oc- curs through a series of diversion ditches carrying the surface flow to vari- ous parts of the"field. The essential hydrologic functions for this portion of the alluvial floors are related to surface flow and not to subirrigation and other ground water flows. Salt Creek Mining Company has also agreed to secure annual production data from the rancher downstream of this operation. This data is to be considered as secondary to the water monitoring program because fluctuations in annual production can also result from factors which are independent of the mining operation. CMLRD finds the proposed surface coal mining operations would not Snterrupt, discontinue, or preclude farming on an alluvial valley floor. There will be no discharge of water frog the mine workings. No development waste or roof fall rock will be disposed of or stored on the bench on any part of the disturbed area. The only potential effect of the operation on water • quality is through the introduction of suspended solids into runoff fron the disturbed area.