Federal dams have been the focus of major disputes involving application of the Endangered Species Act (ESA), especially its §7 prohibitions on federal actions causing jeopardy to protected species. Operating agencies and project beneficiaries have sought to keep the ESA from restricting dam operations, including by arguing that such operations are non-discretionary and thus exempt. In proposing new ESA implementing rules, the Trump Administration suggested, but did not formally propose, that ongoing federal actions should be considered part of the “environmental baseline” for §7 purposes. Redefining the environmental baseline could have dramatically changed over 25 years of practice in applying the ESA to federal dams, reducing or even eliminating crucial §7 protection. Although the Administration ultimately adopted a more modest change, it apparently did so due to legal rather than policy concerns. This Article examines the policy goals that the Administration apparently sought to pursue with the suggested rule, and identifies issues that will likely arise from ongoing efforts to pursue them at the project level. Although the Administration decided against a national rollback, there are sure to be ongoing battles over the application of the ESA to federal dams.