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I I I, I I I I I I I I I, I I I I I I I 002u78 2.0 NOXIOUS WEED SURVEY METHODS 2.1 Noxious Weed Species of Concern Noxious weeds are plant species that are considered to be undesirable by a particular governing jurisdiction because they compete with native species and may result in deterioration of ecological conditions. The State of Colorado Department of Agriculture Noxious Weed Program lists 18 plant species as noxious weeds in Grand County. These 18 species, which are listed in the following table, constitute the focus of the Williams Fork Project noxious weed survey, Grand County Noxious Weed List Common Name I Scientific Name I Common Name I Scientific Name Black henbane I HvosCl'amus nizer Knapweed, spotted I Centaurea macu/osa Canada thistle Cirsium arvense Leafv spurge I Euohorbia esu/a Chamomile, mavweed Anthemis cotu/a I Musk thistle Carduus nutans Chamomile, scentless Anthemis arvensis Orange hawkweed Hieracium auran/;acum Field bindweed Convolvulus arvensis Oxeye daisy Chrysanthemum /eucanthemum Hoarv cress (whitetop) Cw'daria draba Scotch thistle Onooordum acanthium Houndstongue i Cvnoz/ossum olficina/e , Toadflax. dalmation I Linaria da/matica Knapweed, di ffuse Cental/rea dim/sa Toadflax, vellow I Linaria vuil!Gris Knapweed, Russian Centaurea repens Yellow starthistle I Centaurea so/stitia/is Consultation with the Grand County Weed Supervisor confirmed that many of these noxious weed species occur near the Williams Fork Project (Sumerlin 2003). Other potential species of concern within Grand County, although they do not appear on the Grand County Noxious Weed List, are Bull thistle (Cirsium vulgare) and Platte (or prairie) thistle (Cirsium canescens), Bull thistle is on the Colorado Noxious Weed List. However, Platte thistle is not on the state list and is a native species whose occurrence in Middle Park is disjunct from its more common distribution in the eastern plains. Tamarisk (aka saltcedar) (Tamarix ramosissima), an invasive species of considerable concern throughout the desert southwest, does not yet occur in Grand County, 2.2 Noxious Weed Survey Methodology Based on the phenology of the various Grand County noxious weed species, it was detennined that the noxious weed survey of the Williams Fork Project should be conducted during July or early August when conditions would be optimal for finding the weeds in bloom. This is a critical factor in terms of positive species identification and may also be valuable in terms of visually identifying weed infestations from a distance. The noxious weed survey was conducted July 30 through August 1,2003. A pedestrian survey of the project was conducted by a professional botanist to I) identify any noxious weed infestations and 2) characterize the general character of project vegetation and of significant weed locations. The Williams Fork Project noxious weed Williams Fork Reservoir Hydroelectric Project January 2004 Steigers CorporatIOn NOXIOUS Weed Survey Report Page 2