Feasibility of Fish Passage at Alameda Creek Diversion Dam

Feasibility of Fish Passage at Alameda Creek Diversion Dameffect on the currently isolated population’s long-term genetic integrity, in turn supportingpreservation of O. mykiss stock.7.1.5 REDUCE RISK OF EXTINCTION THROUGH INCREASEDNATURAL PRODUCTION AND CREATION OFADDITIONAL INDEPENDENT POPULATIONSPassage at ACDD could potentially create an additional, independent population of steelhead thatcould supplement the existing Central California Coast steelhead DPS. Passage directly aboveACDD would provide access to stream habitat potentially suitable for spawning and rearing, roughlyestimated to be somewhere between 4 and 10 miles based on the limited data available (seeSection 6.1). As described in Section 4.4, this habitat may be sufficient to support 100 pairs ofsteelhead spawners, the estimated number of spawning pairs sufficient to create a sustainablepopulation. This assertion is based on a review of available literature and imposition of professionaljudgment, rather than any direct quantification of spawning habitat or precise measure of currentrainbow trout spawning behavior in Alameda Creek. A detailed spawning habitat survey would needto be conducted to obtain a more accurate picture of habitat availability above ACDD.Passage at ACDD would increase steelhead habitat availability in the Alameda Creek Watershed. Ifsteelhead are re-established at other locations in the watershed, then habitat made available bypassage at ACDD would also be of integrative value to the Alameda Creek Watershed steelheadmetapopulation. Historically, steelhead likely spawned in streams throughout the watershed. Accessto some of these streams may have occurred intermittently, because it would have depended onannual hydrologic conditions or the state of various migration obstacles, and subpopulations withinthe watershed may have historically augmented each other following years of limited production inselect reaches. Therefore, facilitating access to habitat upstream of ACDD could potentially augmenta steelhead metapopulation in the Alameda Creek Watershed. This benefit to a metapopulation couldpotentially exist even if the productivity of the population above ACDD was low in some years, orwas insufficient to sustain itself without contributions from other occupied habitats in the AlamedaCreek Watershed.7.2 OHLONE TRAP AND HAUL OPTIONThis section evaluates the likelihood of the Ohlone Trap and Haul option to meet the goals of fishpassage. As identified in Section 5.3, an Ohlone Trap and Haul fish passage option would include thefollowing three design components:■■■Confluence Fish FacilityCamp Ohlone Haul RouteFish ScreensImmigrating adult steelhead would be captured at the Confluence Fish Facility, located at theconfluence of Calaveras Creek and Alameda Creek, below Little Yosemite (Figure 4-5). Arrivingfish would be transported along the Camp Ohlone Haul Route to their release point above ACDD. Itmay also be desirable to release some of the captured fish immediately above Little Yosemite, toaccess habitat between that potential barrier and ACDD. Screening at the ACDT would prevent fishfrom being entrained in the diversion tunnel, and a fish screen bypass would allow emigratingjuveniles and post-spawn adults safe downstream passage at ACDD.ACDD Passage June 2009 Page 7-4