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Soil Investigations for Data Collection in the Delta Initial Study/Proposed Mitigated Negative Declaration 45 rounded snout, stocky body, and is black with large yellow oval or bar-shaped spots (Stebbins 2003). The species historically occurred throughout the Central Valley and surrounding foothills, from Yolo County south to Tulare County, and in the south coast ranges from north of Monterey Bay to San Luis Obispo County, although many of the populations in the Central Valley are now extirpated. There are also isolated populations in Sonoma and Santa Barbara counties (Nafis 2019) which are listed as Endangered under FESA. California tiger salamander inhabits annual grasslands, open mixed woodlands and oak savanna, spending most of its life underground in small mammal burrows. Central California tiger salamander has been shown to migrate from 1 to 1.3 miles between breeding ponds and upland habitat, depending upon the availability of suitable upland refugia (Jennings and Hayes 1994, Orloff 2007). Breeding occurs in vernal pools, seasonal ponds, and constructed stock ponds that are generally free of fish and hold water during winter, often drying out by summer. Adults move from subterranean refuge sites to breeding pools during relatively warm late winter and spring rains (Jennings and Hayes 1994), usually from November through April. Breeding occurs following rains from December to March (Stebbins 2003). Eggs are laid individually or in clumps on submerged vegetation and debris in shallow water and generally hatch in 10 to 28 days (USFWS 2015a). Larvae are aquatic, taking from three to six months to metamorphose. Post-metamorphic juveniles disperse from breeding sites at night during the late spring or early summer to upland burrows or soil crevices. California tiger salamander has a high potential to occur within the Study Area based upon presence of suitable aquatic and upland habitat and proximity to reported occurrences. There are several reported occurrences of California tiger salamander ranging from 300 feet to less than 0.5 mile from multiple Impact Areas in the southern portion of the Study Area, west of Byron Highway within Contra Costa and Alameda Counties. Implementation of the following mitigation measures to avoid impacts to all suitable aquatic habitat, upland refugia habitat, and individuals that could be moving through the Study Area: MM AES-1, MM AES-2, MM BIO-1, and MM BIO-2, would reduce potential project impacts to California tiger salamander to: Less than Significant with Mitigation Incorporated. MM BIO-1: General Wildlife a. All litter, debris, unused materials, rubbish, supplies, or other material will be appropriately stored in closed containers until it can be removed from project sites and deposited at an appropriate disposal or storage site. All trash that is brought to a project site during soil investigation activities (e.g., plastic water bottles, plastic lunch bags, cigarettes) shall be removed from the site daily.