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<br />fans, shown as Qaf on Map 7 of the addendum. The fan deposits are <br />integrated both hydrologically and agriculturally with the modern <br />stream terraces, and should, therefore, be considered in the alluvial <br />valley floor determination. The applicant has also identified four <br />distinct river terraces south of the area which are covered by <br />alluvial mudflow deposits (see Map 7 of Volume 8). The uppermost <br />terrace (Qt4) appears to be part of a dissected pediment which <br />occupies the geographic highs between the stream valleys. The <br />remaining terraces are topographically lower, and are part of the <br />valley bottom complex. <br />Flood irrigation is very prolific in the Ward and Williams Creek <br />valleys. Eleven major irrigation ditches were identified in the Ward <br />Creek valley, and six major ditches were identified in the Williams <br />Creek valley (See Map 8 of Volume 8) . In addition to the main <br />ditches identified, numerous lateral ditches exist to distribute the <br />water from the major ditches. Water for these irrigation systems is <br />provided, in part, by the Granby Ditch, which transports irrigation <br />water from reservoirs on Grand Mesa. <br />The applicant has indicated that the agricultural practices along the <br />two valleys are predominantly native pasture and hay for stock. <br />There are also some apple orchards in the area, and some fields in <br />small grains (e.g. wheat, oats, and barley). The applicant has <br />provided no specific information concerning the agricultural <br />significance of the alluvial valley floor to farming. Therefore, the <br />areas designated as alluvial valley floor are assumed to be agri- <br />culturally significant, and the Division will make all three alluvial <br />valley floor findings for the Ward Creek-Williams Creek alluvial <br />valley floor. <br />Based on the information provided by the applicant, the areas <br />designated as Qaf, Qtl, Qt2 and Qt3 along the Ward Creek and Williams <br />Creek Valleys are designated as alluvial valley floors because of <br />flood irrigation capability. <br />Pursuant to Rule 2.06.8, the Division is required to make specific <br />written findings on the effect of mining on all AVF's within the <br />permit and adjacent area. The required findings are presented below. <br />1. The mining operations did not interrupt, discontinue, or preclude <br />farming on the alluvial valley floor. The surface facilities <br />associated with the mine are located outside of the area <br />designated as alluvial valley floor. The operation did undermine <br />portions of the area designated as alluvial valley floor but it <br />did not affect farming activities. The applicant performed <br />limited mining (the extraction ratio was between 50 and 55 <br />percent), and, therefore, no significant surface effects from <br />subsidence were expected. In addition, the applicant has a <br />subsidence monitoring plan (Section 2.05.6(6)(f)(ii)(c) of the <br />permit application). <br />2. The mining operations would not materially damage the quantity or <br />quality of surface and ground water which supply the alluvial <br />valley floor. During mining operations, the underground mine <br />slightly depleted flows in the stream/alluvial aquifer system, <br />and the discharge of water from the underground workings affected <br />water quality in the Carbon Ditch and in Ward Creek. After <br />mining operations, when the natural ground water flow pattern is <br />restored, water passing through the underground workings would <br />affect water quality in the Williams Creek and Ward Creek <br />28 <br />