The Build Alternative would result in the conversion of existing vegetated land cover (which provides or supports habitat for fish and wildlife) to new paved areas, stormwater treatment facilities, or different vegetated land cover types. Approximately 19 acres would be permanently converted to paved/built surfaces, and approximately five acres would be permanently converted to different native vegetation types (areas revegetated following construction).
The new roadway would cross Yelm Creek via a new bridge. The bridge would span Yelm Creek and no structures would be placed in or near the channel. There is low-quality aquatic habitat in Yelm Creek. The channel upstream of the planned bridge is dry much of the year. Therefore, the likelihood of the bridge to adversely affect migrating salmon or other fish is extremely low.
The Yelm pocket gopher, an Endangered Species Act (ESA) threatened species, is known to be present in the study area. The Build Alternative would affect approximately 19 acres of suitable habitat for this species, with the potential for direct harm to or disturbance of the animals. Of the 19 acres, five acres would be converted to roadway or other impervious surface, and 14 would be disturbed during construction but not converted to impervious surface. Soil compaction and removal associated with construction would make much, and possibly all, of the 19 acres unusable by Yelm pocket gophers. Over the long term, however, some temporarily disturbed areas could become suitable habitats.
To offset project-related impacts to Yelm pocket gophers, WSDOT plans to establish and maintain three conservation sites. These sites would be dedicated to the conservation of Yelm pocket gophers and regional biodiversity through the restoration, enhancement, protection, and management of the natural areas on which the gophers depend. One site would be adjacent to the new roadway and would not be disturbed during construction. The other two would be established on WSDOT owned parcels in south central Thurston County. Suitable habitat is present and Yelm pocket gophers have been documented at all three sites.
Minimization of effects to fish, wildlife, and vegetation have been taken into consideration for the project. The project was changed to reduce the amount of clearing, soil disruption, and new impervious surface by constructing the shared use path on one side of the road instead of two. Additionally, during construction, clearing would be limited to the minimum necessary area, clearing areas would be marked with construction fencing, construction staging areas would be located away from wetlands or streams whenever possible, and cleared areas would be revegetated with native vegetation following construction.
Best Management Practices (BMPs) would be used to control sediments. Additional surveys would be conducted in potentially suitable habitats before construction and impacts would be avoided or mitigated. Mitigation for impacts to the Yelm pocket gopher would be carried out in consultation with the U.S. Fish and Wildlife Service (USFWS) and local jurisdictions. WSDOT would establish and maintain three sites dedicated to the conservation of pocket gophers and regional biodiversity. Impacts to Oregon white oak habitat would be mitigated by planting new trees as specified in applicable local ordinances.
For more information
To read more about the study approach, existing conditions, and effects on fish, wildlife, and vegetation, please see Section 3.7 Fish, Wildlife and Vegetation (PDF 5.8MB).