8F Consent 2007 0618 - Laserfiche WebLink

Home

middle marsh (pickleweed) occupies about 0.02 acre within the study area (Figure 9). Additional salt marsh vegetation extends along the north levee beyond the study area boundary. Non~tidal salt marsh, vegetated by pickleweed, also occurs to the north ofthe study area (Figure 9). Wetland areas were delineated based primarily on the presence of wetland vegetation (pickleweed and cordgrass, both obligate species found only in wetlands) and hydrology indicators (inundation, calculated tide lines), since the native soils have been altered by the placement of fill (riprap, levee fill material). No fill would be allowed in wetland areas without a permit from any/all of the three agencies. The wetland plant communities and the tidal waters identified within the study area have the potential to be considered jurisdictional by the Corps, the RWQCB, and/or BCnC. A wetland delineation following Corps procedures has been conducted to map the exact location and extent of jurisdictional features within the study area. These data are included in a separate report (WRA, 2005b ). Existing wetlands within the study area are low quality. Salt marsh on the levee is either vegetated by an invasive non~native species (Spartina alterniflora), or consists of scattered pickleweed growing in riprap. These areas are not likely to support rare plant species and would supply virtually no habitat value for wildlife. No fill will occur in these areas as a result of the project and no direct removal of vegetation will occur. The constructed bridge may have some shading impact on patches of vegetation growing underneath it. This impact to degraded wetlands is not considered significant and no mitigation measure is proposed for potential shading impact. The non~tidalpickleweed diked marsh adjacent to and north of the study area is a higher quality wetland resource. This area is not within the project footprint, but may be affected by adjacent construction activities. A mitigation measure is proposed below to avoid impacts to the pickleweed marsh. Three bridge support pilings will be driven into the Bay resulting in placement offill in tidal waters. Permits (Corps, BCnC, and RWQCB) will be required to conduct this work, and mitigation measures approved by USFWS, CnFG, and National Marine Fisheries Service (NMFS) will be implemented as conditions of the permits. These mitigation measures designed to avoid or reduce impacts to special status wildlife species (California clapper rail and salmonids) are described below. No additional mitigation is proposed for impacts to the tidal waters. No riparian habitat occurs within the study area, and no sensitive plant communities, other than wetlands, occur in or adjacent to the study area. However, eighty special status species of wildlife have been recorded or may occur in the vicinity of the study area Brief descriptions of ten wildlife species that are present or with moderate potential to occur (including status, habitat requirements, and known distribution) and why these species are considered to have a moderate potential to occur within the study area are provided below. Although there is a low potential for the California clapper rail (Rallus longirostris obsoletus) and burrowing owl (Athene cunicularia) to occur in the study area, they are also addressed due to their known local occurrences. Of the ten special status wildlife species that have a moderate or high potential to occur within the study area, four typically are only present for brief periods in winter or migration. Based on the results of the biological assessment, six special status species and/or their potential habitat (scrub, grassland, pickleweed areas, and aquatic) may be affected by the proposed path and bridge Y4204lS.00693.doc - 4/5/07 -15-