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Biological Resources, MONK&ASSOCIATES Impacts and Mitigations Tracy Facility Expansion Site in late winter-spring and fall(Jennings and Hayes 1994). Amount of rain may be a better predictor of surface activity than temperature,but the cue or combination of cues that induces emergence in wester spadefoot remains poorly understood(Jennings and Hayes 1994). Larvae take between three and 11 weeks to complete development. CNDDB retards show that in April 1992, spadefoot toad larvae were abundant in pools along Corral Hollow Creek at CDFG's Ecological Reserve,which is approximately 3.0 to 3.5 miles west of the project site. It should be noted that the reach of Corral Hollow Creek where the spadefoot larvae were identified in 1992 is considerably different than the reach of this creek where it flows 'through the project site. Three miles upstream of the project site,Corral Hollow Creek supports emergent and riparian vegetation and deep pools,which is a much different environment from the flashy reach of creek on the project site. Nonetheless,since the reach of Corral Hollow Creek that traverses the project site provides the sandy soils needed by western spadefoot for burrowing (i.e., aestivation sites), and the aquatic environment needed for egg laying and larval development,it can be concluded that suitable habitat for western spadefoot toad exists on the project site. Hence, surveys for this species would need to be conducted prior to impacting Corral Hollow Creek. California red-legged Frog (Rana aurora draytonii)is a Federal listed threatened species and a State"species of special concern." The California red-legged frog is typically found in slow- flowing portions of perennial streams, and in ephemeral streams, and hillside seeps that maintain pool environments or saturated soils throughout the summer months. Riparian vegetation such as willows(Salix sp.) and emergent vegetation such as cattails (Typha sp.)are preferred red- legged frog habitats,though not necessary for this species to be present. This frog is also found in ponds. Populations of California red-legged frog will be reduced in size or eliminated from ponds supporting non-native species such as bullfrogs (Rana catesbiana), Centrarchid fish species (such as sunfish,blue gill, or large mouth bass),and signal and red swamp crayfish (Pacifastacus leniusculus and Procambarus clarkii, respectively), all known California red- legged frog predators. CNDDB records provide two California red-legged frog sightings in Corral Hollow Creek. In 1992, California red-legged frog larvae were observed approximately 3.0 miles upstream of the project site in pools along the creek, and in 1993, three sub-adult red-legged frogs were observed in the creek approximately 4.0 miles from the project site. The reaches of Corral Hollow Creek where these sightings were made are very different from the reach of Corral Hollow Creek that crosses the project site. Where the California red-legged frogs were observed,upstream of the project site, the creek meanders, and deep pools with emergent aquatic vegetation such as duck weed(Lemna sp.) and cattails (Typha sp.) are present. Cottonwoods (Populus fremontii), willows, and the occasional sycamore tree(Plantanus racemosa)provide a riparian.canopy. This riparian environment differs greatly from the open, clear water environment found on the project site. The reach of Corral Hollow Creek on the project site is level bottomed with no deep plunge pools. Additionally, there is no emergent vegetation for escape cover or larval food, and the upland habitat surrounding the creek is barren, providing no escape cover at all near the creek, Without plunge pools-or emergent vegetation,or even upland vegetation,for escape cover,predators such as raccoons would easily be able to capture a resting frog or its larvae in the clear water. Therefore, it is unlikely that California red-legged frogs would be found within 16