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<br />Soil Investigations for Data Collection in the Delta
<br />Initial Study/Proposed Mitigated Negative Declaration 42
<br />3.4.1.1 Methodology
<br />DWR environmental scientists compiled a list of sensitive species and plant
<br />communities that may be in the Study Area (Appendix A). The list was developed from a
<br />review of the California Natural Diversity Database (CNDDB), Sacramento U.S. Fish
<br />and Wildlife Service website (USFWS), and the California Native Plant Society (CNPS)
<br />on-line Inventory of Rare and Endangered Plants for the following 42 USGS 7.5 minute
<br />Quadrangle maps: Gray’s Bend, Taylor Mountain, Rio Linda, Davis, Sacramento West,
<br />Sacramento East, Saxon, Merritt, Clarksburg, Florin, Dixon, Elk Grove, Dozier, Liberty
<br />Island, Courtland, Bruceville, Galt, Lodi North, Thornton, Isleton, Rio Vista, Birds
<br />Landing, Antioch North, Jersey Island, Bouldin Island, Terminous, Lodi South, Stockton
<br />West, Holt, Woodward Island, Brentwood, Antioch South, Tassajara, Byron Hot Springs,
<br />Clifton Court Forebay, Union Island, Lathrop, Tracy, Midway, Livermore, Vernalis, and
<br />Altamont USGS 7.5’ quadrangles. The complete list includes information on species
<br />status, habitat description, whether potential habitat occurs in the Study Area, and
<br />whether the species have the potential to occur within the Study Area.
<br />The Study Area for evaluating the Proposed Project’s potential impacts on sensitive
<br />wildlife species was established with 2 and 5-mile buffers around each soil investigation
<br />site to account for the life histories and potential migration of any given species.
<br />Expected wildlife species’ potential to occur within the Study Area were determined
<br />through a review of CNDDB Geographic Information System (GIS) records (CDFW
<br />2019), iNaturalist (2019) research grade occurrences2, and analysis of aerial imagery.
<br />This evaluation does not include specific information that could only be attained via site
<br />visits, which have not been conducted for the project footprint.
<br />The Study Area for evaluating the Proposed Project’s potential impacts on sensitive
<br />plants was established as a 100-meter buffer around each soil investigation site. This
<br />buffer was established to account for potential site relocation and vegetation map
<br />resolution. Habitat types within the Study Area were characterized by the 2007
<br />Vegetation and Land Use Classification and Map of the Sacramento-San Joaquin River
<br />Delta (Hickson & Keeler-Wolf 2007). These types were cross-walked to their respective
<br />Holland natural community types (Holland 1986, Sawyer et al 2009), which are used by
<br />the CNDDB and CNPS for habitat characterization of special-status plants (CNPS
<br />2019).
<br />Each species’ potential to occur within the Study Area was determined by:
<br />1) comparing natural community types within the Study Area to suitable habitat
<br />for each species, and
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<br />2 A research grade is applied to an occurrence submitted to iNaturalist when the
<br />following has been verified: date is specified and accurate, location is specified and
<br />accurate, includes photos or audio, has ID confirmed by two or more people, the
<br />organism is wild and there is adequate evidence of the organism, and it is identified to
<br />species.
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