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THREATENED AND ENDANGERED SPECIES HABITAT ASSESSMENT <br />BEARSON PROPERTY <br />WELD COUNTY, COLORADO <br />considerations or protections. Section 7 of the ESA prohibits destruction or adverse <br />modification of critical habitat by any activity funded, authorized, or carried out by any <br />federal agency, such as issuance of a Section 404 permit. In 2010, the Service revised its <br />designation of critical habitat for Preble's and does not include any areas along St. Vrain <br />Creek or its tributaries in Weld County (75 Fed. Reg. 78481, December 15, 2010). <br />Potential Habitat and Possible Effects <br />Vegetation community types and habitat connectivity are the key elements in <br />determining the suitability of habitat in the project area to support viable populations of <br />Preble's. Although the project area contains herbaceous wetlands and planted <br />windbreaks that replicate woody riparian habitat providing some of the habitat features <br />described above for Preble's, these narrow vegetation communities are completely <br />isolated and fragmented from potentially suitable habitat along St. Vrain Creek. A review <br />of aerial photography also revealed that most of the windbreaks are fairly young and <br />poorly developed as recently as 1999. Furthermore, the area identified as Wetland 1 was <br />mowed or hayed as recently as 2004. A survey field data compilation form is provided in <br />Appendix A. <br />Colorado Butterfly Plant <br />Species Background <br />The Colorado butterfly plant (CBP) is federally listed as threatened. The CBP is a <br />short-lived perennial herb found in moist areas of floodplains. It occurs on subirrigated, <br />alluvial soils on level or slightly sloping floodplains and drainage bottoms at elevations <br />from 5,000 to 6,400 feet. The CBP is found in active floodplain along perennial streams <br />and where vegetation is relatively open. Colonies are often found in low depressions or <br />along bends in wide, active, meandering stream channels that are periodically disturbed <br />Service 2004). Its historical and current distribution in Colorado includes Boulder, <br />Douglas, Larimer, and Weld counties. The CBP flowers from June to September and <br />produces fruit from July to October (Spackman et al. 1997). <br />5