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Draft Supplemental Environmental Impact Report Page IV.F-11 Forward Inc. Landfill 2018 Expansion Project and riparian wildlife species,but is not expected to provide suitable habitat for salmonids due to low flows and the highly modified flow regime. Giant Garter Snake The giant garter snake (Thamnophis couchi gigas)is a federally and state-listed Threatened species. Giant garter snake(GGS)is a large dull colored snake endemic to the valley floor wetlands of Sacramento and San Joaquin Valleys of California (USFWS 1999b). Giant garter snakes are highly aquatic and inhabit freshwater marshes, low-gradient streams, drainage canals, and irrigation ditches, especially those associated with rice farming from Butte County to Fresno County. Currently, 13 populations of giant garter snakes are recognized,which correspond to historic flood plains and tributary streams throughout the Central Valley. San Joaquin County is one of the 11 Counties in the Central Valley where the giant garter snake is still presumed to occur. The abundance and distribution of giant garter snakes has not changed significantly since the time of federal listing: many populations north of Stockton ' remain stable,while the two known populations south of Stockton remain small, fragmented, and unstable and are probably decreasing(USFWS 2006). The closest records of giant garter snake to the project site are south of Stockton, approximately 7 miles north and east of the project site,within the East Stockton--Diverting Canal and "canals just west of historic Stockton' (CNDDB 2018). In addition, a 55-acre wildlife preserve for giant garter snake and Pacific pond turtle was created on BNSF Railway property approximately 1.5 miles northeast of the study area. The South Branch of the South Fork of Littlejohn's Creek has little value for the giant garter snake due to the lack of permanent water within the channel and the lack of emergent wetland vegetation as a result of periodic flood maintenance and low flows. Upland refugia habitat is also of poor quality surrounding the creek due to the lack of tall grasses and other vegetation ' due to mowing for flood control and frequent disturbance of agricultural fields and landfill areas adjacent to the study area. Sacramento Splittail Sacramento splittail (Pogonichthys macrolepidotus) is a California Species of Special Concern. The Sacramento splittail inhabits rivers, lakes,sloughs and estuaries of the Sacramento-San Joaquin Delta, Central Valley, Suisun Bay,Suisun Marsh, and the San Francisco Bay. For spawning, Sacramento splittail require shallow water areas with submerged vegetation,habitats typically caused by late winter and spring flooding of natural stream banks. Operation of federal, state, and private water development projects,including water storage, diversions,releases,export and agricultural return flows,reduce the availability and quality of this habitat. Primary threats to the species also include decline of water quality caused by the export of water from the Sacramento and San Joaquin rivers, drought, introduced aquatic species, and agricultural and industrial pollutants (USFWS 1999a). Due to the presence of Sacramento splittail within the San Joaquin River and tributaries,this species could possibly get as far upstream in Littlejohn's Creek at the project site during wet