Biotic Resources Group

Transcription

1 Biotic Resources Group Biotic Assessments Resource Management Permitting Proposed Offsite Trail Connection Within Caltrans Right-of-Way Biological Review May 2013 The Biotic Resources Group conducted a biological review of a proposed offsite trail connection within the Caltrans R-O-W under the existing Highway 101 overpass parallel to the Petaluma River. A field visit was conducted on May 13, The findings of the review are described in this memo. The trail within the R-O-W will be approximately 850 linear feet long. The majority of the trail (approximately 600 linear feet) will be constructed within an area recently disturbed by Highway construction activities that is currently barren (see attached Figure 1). The remainder of the trail route will traverse patches of ruderal herbaceous vegetation, small patches of coastal brackish marsh (i.e., areas supporting pickleweed and fat hen), and cross a narrow, tidally-influenced drainage channel. The small patches of coastal brackish marsh and the tidally influenced drainage channel are expected to be jurisdictional under USACOE regulations. The trail will be located approximately 50 feet south of two seasonal wetlands that are located in depressions west and east of Highway 101 (see attached Figure 1). These wetland depressions are also expected to be jurisdictional under USACOE regulations. The seasonal wetlands may provide suitable habitat for two special status species: common yellowthroat and salt marsh harvest mouse. Both of these species have been documented east of Highway 101. Wetland and species avoidance measures were implemented by Caltrans as part of the current highway improvement project. No other special status plant or animal species were observed during a May 2013 site reconnaissance and none are expected due to the degraded condition of the habitats in the project area. The development of the trail (i.e. grading for trail construction, bridge over tidally-influenced drainage channel, and other trail amenities) may impact the coastal marsh wetland and drainage channel if these resources are not protected during construction. In addition, depending upon the specific design of the trail (i.e., exact alignment, width, surface improvements), the proposed trail could result in a direct impact to some of the small coastal brackish marsh patches that occur east of the drainage channel. The following measures are recommended to reduce impacts to sensitive biological resources to a less than significant level: 1. Conduct a delineation of Waters of the US to document distribution of jurisdictional areas; determine impacts to such resources from the trail project and implement wetland mitigation measures as outlined in the Riverfront Mixed Use Development. 2. Minimize impacts to the tidally-influenced drainage channel by constructing a freespanning bridge over the channel and locating bridge abutments in upland areas outside the channel banks South Rodeo Gulch Road #12 Soquel, Californica (831) brg@cruzio.com

2 3. Implement measures to avoid impacts to the salt marsh common yellowthroat and salt marsh harvest mouse habitat. Implement avoidance actions as per those implemented by Caltrans as part of the highway improvement project and/or those identified by resource agencies; measures are expected to include: pre-construction worker training, installation of exclusion fencing and construction barrier fencing, presence of an on-site biological monitor during vegetation stripping, and post-construction reporting. 4. Areas temporarily disturbed by construction shall be revegetated with a native grass and forb seed mix compatible with the Petaluma River region. 5. Implement measures to avoid impacting nesting birds, if present. Conduct trail construction outside the bird-breeding season or conduct pre construction nesting surveys to ensure that no birds are nesting in or immediately adjacent to the work area. Photos of Project Area Existing avoidance fencing between seasonal wetland east of Highway 101 and highway construction 2 P a g e

3 Proposed trail route, looking east from Highway 101 construction area Coastal brackish marsh (pickleweed) patches at eastern end of proposed trail route 3 P a g e

4 Tidally-influenced drainage channel, looking downstream toward Petaluma River Seasonal wetland east of Highway 101, showing wetland avoidance measures associated with Caltrans construction 4 P a g e

5 Proposed trail route along existing Caltrans construction access road under Highway 101 Petaluma River downstream of Highway 101, looking upstream (west) 5 P a g e

6 Legend Seasonal Wetland (approximate boundaries) Coastal Brackish Marsh (patches) Herbaceous Ruderal Tidally-influenced Drainage Channel B Barren (recently disturbed by Caltrans construction) B B Petaluma River Figure 1. Existing vegetation at proposed trail within Caltrans R-O-W