Opinion ID: 3066157
Heading Depth: 4
Heading Rank: 2

Heading: Aquatic Macrophytes

Text: Another stressor noted in the BiOp is aquatic macrophytes. Macrophytes—aquatic plants that grow in or near water—have extensively colonized the interior Delta over the past two decades. BiOp at 182. As the BiOp notes, research suggests that these macrophytes have “altered fish community dynamics in the Delta, including increasing habitat for centrarchid fishes including largemouth bass, reducing habitat for native fishes, and supporting a food web pathway for centrarchids and other littoral fishes.” BiOp at 182 (citations to scientific studies omitted). These effects impact smelt both directly and indirectly. Submerged aquatic vegetation can overwhelm littoral habitats, such as inter-tidal shoals and beaches, that serve as delta smelt spawning locations, thereby rendering them unsuitable for spawning. BiOp at 182. Moreover, macrophytes trap suspended sediment and therefore reduce water turbidity, which has contributed to a decrease in both juvenile and adult smelt habitat while increasing the available habitat for fish that prey on smelt. BiOp at 182–83 (citing Feyrer et al. 2007 and Nobriga et al. 2008 in support). This decreased turbidity also may facilitate the predation of delta smelt while hampering the smelt’s own feeding, thereby further harming smelt population viability. BiOp at 183. As the BiOp notes, hydrologic conditions and water temperature play a significant role in macrophyte colonization of the Delta. BiOp at 182. The FWS concludes that it is “likely” that Project operations’ impact on Bay-Delta hydrologic conditions and reduction of seasonal flushing 108 SAN LUIS V. JEWELL flows exacerbate the spread of macrophytes in the Bay-Delta. BiOp at 277. Flushing flows are known to lead to “abrupt changes in flow and turbidity.” BiOp at 146. Indeed, the FWS found that “[a]vailable information is inconclusive regarding the extent, magnitude and pathways by which delta smelt may be affected by these stressors independent of CVP/SWP operations.” BiOp at 277. The district court was also not persuaded by this analysis, finding that “[a]lthough a connection [between Project operations and macrophytes] may exist, the record does not reflect any discussion, nor have the parties pointed to any study, connecting ‘seasonal flushing flows . . . the natural frequency of upstream and downstream movement of the LSZ, and lengthen[ed] upstream shifts of the LSZ’ to the presence of any aquatic macrophyte.” San Luis & DeltaMendota, 760 F. Supp. 2d at 935–36. Again, we disagree. The BiOp set forth several plausible explanations for how Project operations will increase the detrimental impact of macrophytes on delta smelt viability, and cited studies in support. See BiOp at 146, 182–83, 277. That the BiOp did not, as the district court requests, point to a study directly addressing the Project’s effect on Bay-Delta macrophytes does not render the FWS’s conclusions unreasonable or unsupported: The FWS has drawn rational conclusions from the best available science, and, consequently, we hold that the BiOp’s determination that it is reasonably certain that macrophytes will indirectly affect delta smelt is not arbitrary and capricious. It is not our job to task the FWS with filling the gaps in the scientific evidence. We must respect the agency’s judgment even “in the face of uncertainty.” Ariz. Cattle Growers Ass’n v. Salazar, 606 F.3d 1160, 1164 (9th Cir. 2010). SAN LUIS V. JEWELL 109