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F-T, 3 INTRODUCTION A noxious weed control and monitoring program was initiated in 1998 by the Division of Minerals and Geology (DMG), at the inactive Coa] Basin Mine. DMG, in conjunction withPitkin County, was awarded a grant from the Colorado Department of Agriculture, for the purpose of managing serious noxious weed infestations that had developed at vazious reclaimed azea locations within the permit boundary. The mine permit area is located within the upper reaches of the Coal Creek drainage, approximately four miles west of Redstone. Coal mining activities began in the permit azea vicinity in the 1890's, were discontinued in the eazly 1900's, and resumed on a much larger scale in the midd950's. Mid-Continent Resources (MCR) and its predecessors operated a complex of five underground mines and associated processing and transportation facilities within Coal Basin from about 1955 until 1990. In the early 1990's, the mine ceased operation. MCR filed for Chapter t 1 Bankruptcy protection, and began to liquidate its assets. Eventually, MCR's mining permit was revoked and the reclamation bond forfeited by the Colorado Mined Land Reclamation Boazd. As required by applicable statute, the Colorado Department of Natural Resources, Division of Minerals and Geology, undertook the task of reclaiming the mining disturbances through the use of funds obtained from the banlavptcy liquidation plan. Mine reclamation is now lazgely completed. The weed control program was initiated to manage significant infestations of noxious weeds that were present on approximately 60 acres of reclaimed land within lower portions of the Coal Basin complex. Weed infested reclaimed sites included a conveyorbelt[ine corridor and coat stockpile area, a coal refuse pile known as the Sutey Pile, and associated facility azea disturbances. Average elevation of the treatment azeas was 9,000 to 9,500 feet above sea level. Primary tazget species wereplumeless thistle (Carduus acanthoides) and hounds[ongue (Cynoglossum o)~crnale), both biennials; and the perennial Canada thistle (Breea arvense). Secondary species of concern were the biennial musk thistle (Carduus nutans) and the perennial oxeye daisy (Chrysanthemum leucanthemum). A number of organizations and agencies have participated in the project by offering in-kind services, funding, or materials. Partners in the project in addition to DMG andPitkin 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, athree year control program was envisioned, with continued treatment as warranted. Control program objective was a 75% reduction in noxious weed density within We treatment azeas. Tordon (picloram) at one or two quarts per acre has been applied to each treatment azea at least annually in eazly July, since 1998, using a combination of truck mounted and backpack spraying equipment. Spray operations were conducted twice per yeaz (eazly July and September), in 1998 and 2000. The two quart per acre application rate was typically used, with the lower rate applied in portions of the treatment azeas where infestations were less severe. In 2000, goat grazing combined with mechanical control (chopping ofun- grazed plumeless thistle flowering stalks) andinterseeding was applied to certain sites. Although not a planned control agent, a heavy larval infestation of the painted lady butterfly Q~anessa cardur) was observed on remaining thistle patches within portions of the azea in 2001. The primary purpose of this report is to summarize the results of monitoring that was conducted annually from 1998 through 2001. In order to document appazent treatment effectiveness, four reference sites were established in representative locations within the treatment azeas. Refer to Map 1 for the vazious treatment azea Iocations, and approximate locations of Reference Areas 1 through 4. Noxious weed densities and cover based vegetative species composition data were collected within the reference sites prior to initial treatment in June 1998, and data were collected within the same reference sites just prior to summer spraying operations in 1999, 2000, and 2001. Success of the program with respect to tazget species control was based primazily on noxious weed density data, while the species cover and composition data allowed for assessment of plant community response and appazent impacts to non-target vegetation.