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COAL BASIN MINE NOXIOUS WEED CONTROL PROJECT EXECUTIVE SUMMARY The Division of Minerals and Geology (DMG), m conjunction with Pitkin County, was awarded a grant from the Colorado Department of Agriculture in 1998, for the purpose of managing a noxious weed infestation at the Coal Basin Mine. Coal Basin Mine is a large underground mining complex located on White River National Forest and private lands neaz Redstone, Colorado. In the early 1990's, mining operations ceased, the operator filed for bankruptcy, and ultimately the mining permit was revoked and the reclamation bond forfeited by the Colorado Mined Land Reclamation Board. Mine reclamation has been conducted by DMG, and is now largely completed. Significant infestations of noxious weeds were present on approximately 60 acres of reclaimed refuse piles and facility areas. Species of primary concern were the biennials plumeless thistle (Carduus acanthoidesJ, and houndstongue (Cynogfossum o~cinale), and the perennial Canada thistle (Breea arvense). Secondary species of concern were the biennial musk thistle (Carduus Hurons) and the perennial oxeye daisy (Chrysanthemum leucanthemum). A number of organizations and agencies have participated th the project by offering in-kind services, funding, or materials. Partners in the project in addition to DMG-and Pitkin County, included the U.S. Forest Service, the Office of Surface Mining, and the Aspen Wilderness Workshop. Program goals were to reduce the severity of noxious weed infestation to allow for establishment of desirable and effective vegetation cover and minimize the risk of spread to adjacent undisturbed azeas. Initially, a three year control program was envisioned, with continued treatment as warranted. Control objective was a 75% reduction in noxious weed density. To document treatment results, four reference sites were established in representative locations within the treatment areas, designated `5utey Pile Flat" (Reference Area #1), "West Slope Su[ey Pile" (Reference Area #2), "Belt-line Flat" (Reference Area #3), and "Belt-line Outslope" (Reference Area #4). See Map I for weed treatment areas and approximate reference area locations. Noxious weed densities and cover based vegetative species composition data were collected prior to initial treatment in June 1998, and data have been collected annually through 2001. Species composition data were collected primarily to monitor over-all plan[ community response, and impacts to non-target vegetation. Tordon (pic[oram} at one to two quarts per acre has been applied at least annually in early July to each treatment area, using a combination of truck mounted and backpack spraying equipment. Spray operations were conducted twice per yeaz (early July and September), in 1998 and 2000. In 2000, goat grazing combined with mechanical control (chopping ofun-grazed plumeless thistle flowering stalks) and in[erseeding was applied to portions of the azea (including the Sutey Pile reference sites). Comparison of 1998 and 2001 data reveals downwazd population trends for noxious species in all reference areas. At the "Sutey Flat", where thistle species dominated the noxious component, thistle density declined approximately 94%, from 17.5 plants per squaze meter [0 1 plant per square meter. At "West Slope Su[ey", density of the noxious species declined by approximately 75%, from 10.3 plants per squaze meter to 2.6 plants per squaze meter. Density of the primary noxious species at "Belt-line Flat" declined by approximately 95%, from 10.7 plants per squaze meter to 0.5 plants per square meter. At "Bel[•line Outslope", due to very severe initial infestation of various noxious thistle species and oxeye daisy, density was not measured, but absolute cover of noxious species declined from 41% in 1998 [0 2% in 2001. Over-all, the treatment program appears [o have achieved control objectives. Some follow-up spraying will likely be employed within the "West Slope Sutey" reference area and adjacent slopes of the Sutey Pile treatment area, in combination with reseeding, mechanical control measures, and possible goat grazing. No additional control measures or seeding efforts appeaz to be warranted at this time for the `Sutey Flat", "Beltline Flat", or "Beltline Outslope" reference sites and adjacent areas.