ARCHIVED REPORTS_DRAFT ENVIRONMENTAL IMPACT REPORT

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Based on literature data, optimal rearing conditions are obtained at temperatures of 44°F through 69°F, depending on the life history function being evaluated(e.g.,rearing, smoltification, emigration)or the nature of the study (field or laboratory). Four studies postulate optimal temperatures in the 44°F to 60°F range,but USFWS (1997) notes that there are low to high chronic stress effects at temperatures above 50°F and Zaugg et al. (1972) suggests that maturation(i.e., smolting) is affected in the 50°F to 59°F range. The upper lethal limit for steelhead is approximately 75°F(Bjornn and Reiser 1991). Temperatures over 70°F can result in respiratory distress for steelhead due to reduced dissolved oxygen levels(NMFS 2003). Based on available information,the following temperature guidelines have been identified for juvenile steelhead: ► Optimal range: 44°F to 60°F ► Range of increasing adverse effects: 61'F to 68°F ► Lethal effects: >69°F ► Behavioral avoidance: reported at 68°F Green sturgeon On April 6,2005,NMFS proposed a threatened status listing for the southern distinct population segment(DPS) of North American green sturgeon(70 FR 17386). In North America, green sturgeon is found from Ensenada, Mexico,to Southeast Alaska. Green sturgeon is not abundant in any estuaries along the Pacific coast,although they are caught incidentally in the estuaries by the white sturgeon fishery. Like all sturgeon species it is anadromous,but it is also the most marine-oriented of the sturgeon species (NMFS 2005). Green sturgeon is thought to spawn every three to five years(Tracy 1990). Their spawning period is March to July,with a peak in mid-April to mid-June(Moyle et al. 1992). Green sturgeon spawning occurs in deep pools or holes in large,turbulent river mainstems(Moyle et al. 1992). Specific spawning habitat preferences are unclear, but are likely large cobbles,but can range from clean sand to bedrock. Eggs are likely broadcast over the large cobble substrate where they settle into the space between the cobbles. Temperatures above 68°F are lethal to green sturgeon embryos and temperatures above 66°F will lead to reduced growth(Cech et al. 2000). Juveniles appear to spend one to three years in freshwater before they enter the ocean(Nakamoto et al. 1995). Green sturgeon spawning has only been documented in the Klamath, Sacramento (Moyle et al. 1992, CDFG 2002)and Rogue(Erickson et al. 2001,Rien et al. 200 1)rivers during recent times. Green sturgeon spawning in the San Joaquin River is not well documented. Based on available information,the following temperature guidelines have been identified for green sturgeon: ► Range of increasing adverse effects: >66°F to 74°F ► Lethal effects: >68°F (embryos) Delta smelt Delta smelt were listed as threatened under the ESA on March 5, 1993 (59 FR 440). On December 19, 1994(59 FR 65256),USWFS designated critical habitat. Delta smelt were also listed as threatened under CESA in 1993. Delta smelt are found only from the Suisun Bay upstream through the Sacramento-San Joaquin Delta. Delta smelt are endemic to the Delta and occur primarily in open surface waters of Suisun Bay,in the Sacramento River downstream of Isleton, and in the San Joaquin River downstream of Mossdale(near the WQCF discharge outfall) (USFWS 1994). They used to be one of the most common pelagic (living in open water away from the bottom)fish in the upper Sacramento-San Joaquin estuary(USFWS 2004). The delta smelt population generally is concentrated in the estuary west of the confluence of the Sacramento and San Joaquin rivers in high-outflow years and in the Delta in low-outflow years(Sweetnam 1997, 1998). Delta outflow determines the location of the salinity gradient and may strongly influence delta smelt distribution. USFWS data indicate that delta smelt are EDAW Manteca WQCF and Collection System Master Plans EIR Fisheries and Aquatic Resources 4.13-8 City of Manteca