In both Sweden and Finland, water law has traditionally provided strong protection for hydropower operations by issuing permanent environmental licences. This national protection has started to erode as a result of the requirement of the European Union (EU) Water Framework Directive (WFD) for permit reviews to improve the ecological status of rivers. In the light of this dynamic between European and national frameworks, this article compares the Swedish and Finnish implementation of the WFD regarding existing hydropower operations. Whereas Sweden has adopted comprehensive legislative and policy reforms that embrace a systemic perspective on reconciling hydropower with the current societal and ecological circumstances, Finland has relied on bottom-up collaborative processes at the grassroots level. The article shows that both approaches are problematic in so far as they push the boundaries of proper implementation of the WFD and, by extension, the achievement of the ecological objectives of the WFD in waters affected by hydropower. Our comparison highlights tensions between EU law requirements for formal legal effectiveness in national implementation, and the WFD's aspirations for adaptive river basin-based governance.