Road Ecology Center

The California Department of Transportation (Caltrans) conducted mitigation work to establish and protect native wetland and riparian habitat on approximately 0.5 hectare (1.3 acres) adjacent to Dan Wilson Creek. Dan Wilson Creek is located in the Solano Community College property just off of Suisun Valley Road in Fairfield, California. This work mitigates for impacts to 0.07 hectare (0.17 acre) of wetland habitat and 0.05 hectare (0.13 acre) of riparian habitat resulting from the Solano Interstate Route 80 Widening Project located between Interstate 680 and State Route 12 East. Caltrans began construction on the I-80 Widening Project in the fall of 2003. Mitigation work coincided with the widening of Interstate 80 over Dan Wilson Creek that occurred during the summer of 2004. Approximately 0.16 hectare (0.40 acre) of the land contoured, graded, and planted at the mitigation site will provide riparian habitat and 0.20 hectare (0.50 acre) will provide wetland habitat after the five-year monitoring period to meet the mitigation goals established by Caltrans, the California Department of Fish and Game, and the U.S. Army Corps of Engineers. Caltrans biologists obtained a photographic record of the mitigation site in June 2004 before it was graded and contoured. These biologists will obtain photographic records of the same location(s) annually during the five-year monitoring period to monitor the progress of the mitigation project. Caltrans biologists will conduct spring and summer plant surveys to detect early and late-season species and will map the extent of the vegetation cover using a Global Positioning System (GPS). Caltrans biologists will use a minimum of 20 vegetation sample plots, each measuring 3 x 3 meters (10 x 10 feet), to estimate plant coverage and dominance and will collect information on wildlife observed at the mitigation site on an opportunistic basis. The majority of plants installed at the mitigation site have been successful as of June 2005. Approximately 90% of the plants installed in the upland and upland-riparian zones of the mitigation site showed signs of growth. Approximately 488 (91%) of the 535 planted arroyo willows were found in the mitigation area, with 313 (64%) of the counted willows showing signs of growth. Some of the installed wetland plants, including common tule (Scirpus acutus var. occidentalis), have established and spread throughout the wetland zone. Animal species identified by Caltrans biologists in the area before the mitigation work began were again observed in the area after the work. Some of the aquatic species have migrated into the newly developed wetland from Dan Wilson Creek. The number of bird species observed in the area increased after the mitigation work. Birds commonly observed in freshwater pond habitats are using the wetland.