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1.0 INTRODUCTION <br />This report provides a noxious weed control plan for the Mesita Hill Mine (Mine Id # M-1977- <br />227) in Costilla County, Colorado. Bamberg Ecological was retained to complete this plan by <br />Hecla Mining Company. Mesita Hill is an open-pit volcanic scoria mining operation encompass- <br />ing a 201.2-acre permit area and is located in southern Colorado in the San Luis Valley east of <br />Highway 159 (Sec 26, Township 2 North, Range 74 West of the 6`h Principal Meridian). The <br />mine has been in operation since 1948 but is currently in the process of closure due to the lack <br />of interested buyers for the remaining mineral resources. <br />During an October 2005 site visit, an inspector from the State of Colorado Division of Minerals <br />and Geology noted two patches of noxious weeds, specifically: <br />"Near the concrete structures at the entrance two small, well-established patches <br />of noxious weeds were observed: Canada thistle (about 20 ft x 50 ft), and Rus- <br />sian knapweed (about 30 ft x 60 ft)."' <br />Management approaches to these two noxious weed species, a literature review of the species, <br />and results from a site visit made by Bamberg Ecological on December 27, 2005, are contained <br />herein. Please note that Bamberg Ecological did not identify the target weed species due to <br />their being dormant during the December inspection, but accepted the identification as reported <br />by the State Inspector (see Footnote 3). <br />2.0 SITE CONDITIONS <br />The San Luis Valley is a semi-desert landscape with vegetation dominated by arid-tolerant <br />shrubs and shortgrass prairie species. Shrubs in the surrounding landscape are generally of a <br />low-growing habit and are dominated by broom snakeweed (Gutierrezia sarothrae), rabbitbrush <br />(Chrysothamnus sp.), winterfat (Ceratoides Janata), and saltbush (Atriplex sp.). Grasses are <br />dominated by blue grama (Bouteloua gracilis); other grasses may historically have been more <br />dominant but appear to have been diminished by livestock grazing. Local land use, which is <br />restricted by the lack of surface water, is rangeland and wildlife habitat. The annual mean tem- <br />perature is 42.2°F with an average annual total precipitation of 11.8" from rain (9.2") and snow <br />(26.0" at 2.6" water equivalent)2. The growing season averages 94 days. <br />' Minerals Program Inspection Report for Mine Id # M-1977-227 inspection date 10/18/05 <br />z Data from National Weather Service, U.S. Department of Commerce <br />