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<br />channel (Figure 3, Addendum I of the permit aplication). Along <br />Bolton Draw, this alluvium has been identified as an alluvial <br />valley floor. Here, along North Fork, that determination cannot <br />easily be made. <br />The alluvial deposits are approximately 100-200 feet wide at <br />this location comprising approximately 10 acres (Exhibit 2, Vol. <br />1 of the permit application). Alluvium here is distinguished <br />from that in upper North Fork because it represents an alluvial <br />water table that is potentially continuous along all of Bolton <br />Draw. Subirrigation is also suggested by water levels of 6 to 10 <br />feet below ground level measured in Well 2. Although the <br />applicant did not identify vegetation or soil mottling indicative <br />of su.birrigation, the extent of investigations in this particular <br />area is unclear (p. 109-112, Vol.l and Figure 3 of the permit <br />application). The OSM June 11, 1980 AVF Guidelines have not set <br />a particular minimum groundwater level for consideration of <br />Subirrigation, but studies referenced in that report (Preamble, <br />p.12) indicate that the potential exists at levels similar to <br />those measured in Well 2. <br />As discussed for North Fork within the permit area, regional <br />precedence does not exist for flood irrigation on acreage of this <br />size. However, this area could be considered as an upstream <br />extension of the AVF below the stockpond. In that case, some <br />precedence does exist for irrigation of this more extensive <br />acreage, as discussed under the section on Bolton Draw in this <br />part of the TEA. <br />This unit of alluvium will not be physically disrupted by <br />mining at Canadian Strip, therefore, continuing collection of <br />~~ data at Well 2 is sufficient for monitoring mining impacts to <br />~p° this potential AVF. If future mining activities are anticipated <br />in this area, further investigations are needed to determine the <br />extent of effective Subirrigation and to define the hydraulic <br />connection between this alluvium along North Fork and that below <br />the stockpond. <br />_87_ <br />