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The Mesita Hill mine site is a broad, low-relief, basaltic shield volcano with typical slope angles <br />of one to two degrees. The scoria material in this location is only slightly welded and, due to <br />slow market demand, has been mined over the long term. For this reason, the Mesita Hill min- <br />ing operation, which used no blasting, has been relatively undisruptive as compared to open-pit, <br />hard-rock, gold mining operations. The mine's north pit, at about 40-50 feet deep, is the largest <br />of the mine's pits. <br />The majority of the mine site was bare of vegetation during the December 2005 site visit. In <br />particular, a large central area of several acres is covered in waste scoria (1-2 inches in diame- <br />ter) on top of fine, powdery soil; this large area is also mostly unvegetated. However, some <br />natural revegetation of desirable plants, primarily by rabbitbrush and fourwing saltbush (Atriplex <br />canescens), is occurring. Reclamation areas at the entrance to the mine appeared to be well <br />revegetated and successful. <br />The two patches of noxious weeds identified in the State Inspector's report were observed dur- <br />ing the December 2005 site visit. As noted in the State Inspector's report, at this time the <br />patches are isolated and the weeds have not yet spread to the rest of the mine site. Although <br />comprising less than one percent total cover, young individuals of the nonnative Russian thistle <br />(aka tumbleweed; Salsola iberica) are beginning to grow in this area. Russian thistle is not cur- <br />rently considered a noxious weed and can generally be controlled with adequate reclamation. <br />Therefore, this colonization by Russian thistle is not considered a problem or addressed in the <br />current plan as a noxious weed (see Section 5.0 for further discussion). <br />3.0 RUSSIAN KNAPWEED (ACROPTILON OR CENTAUREA REPENS7 <br />Russian knapweed (see Figure 1), adeep-rooted perennial native to southern Ukraine, south- <br />east Russia, Iran, Kazakhstan and Mongolia, typically invades degraded areas but can invade <br />and persist in numerous ecosystems, including rangeland, pastures, agricultural fields, riparian <br />areas, and wildlands. It can establish in saline, alkaline, low lying areas but ultimately prefers <br />deeper soils with higher available moisture. The weed forms dense, long-lived (>75-year) <br />monocultures due to effective competition that includes allelopathy (biochemicals produced by <br />the plant that inhibit the growth of other plants). <br />2 <br />