Long-term protection is needed to secure threatened freshwater ecosystems and the social and biodiversity values they provide. In the face of existing and future pressures, current approaches to freshwater protection are often inadequate for maintaining ecosystem values into the future. While terrestrial and marine ecosystem protection are well recognized and have area-based protection goals in global conventions, freshwater ecosystem characteristics have remained poorly represented in these goals. Freshwater ecosystems are commonly secondary or unaddressed components of area-based terrestrial protection. The design and management for terrestrial-based protection are generally inadequate for addressing freshwater ecosystem processes and attributes critical for maintaining their natural patterns and the values they provide to people and nature. Given that freshwater-dependent species are declining at a faster rate than marine and terrestrial species, and the reliance and use of freshwater ecosystems by people living around such areas, approaches to protect them must balance the needs of people and nature and accommodate these complexities.

As governments and non-state actors strive to minimize global warming, a primary strategy is the decarbonization of power systems which will require a massive increase in renewable electricity generation. Leading energy agencies forecast a doubling of global hydropower capacity as part of that necessary expansion of renewables. While hydropower provides generally low-carbon generation and can integrate variable renewables, such as wind and solar, into electrical grids, hydropower dams are one of the primary reasons that only one-third of the world’s major rivers remain free-flowing. This loss of free-flowing rivers has contributed to dramatic declines of migratory fish and sediment delivery to agriculturally productive deltas. Further, the reservoirs behind dams have displaced tens of millions of people. Thus, hydropower challenges the world’s efforts to meet climate targets while simultaneously achieving other Sustainable Development Goals. In this paper, we explore strategies to achieve the needed renewable energy expansion while sustaining the diverse social and environmental benefits of rivers. These strategies can be implemented at scales ranging from the individual project (environmental flows, fish passage and other site-level mitigation) to hydropower cascades to river basins and regional electrical power systems. While we review evidence that project-level management and mitigation can reduce environmental and social costs, we posit that the most effective scale for finding balanced solutions occurs at the scale of power systems. We further hypothesize that the pursuit of solutions at the system scale can also provide benefits for investors, developers and governments; evidence of benefits to these actors will be necessary for achieving broad uptake of the approaches described in this paper. We test this hypothesis through cases from Chile and Uganda that demonstrate the potential for system-scale power planning to allow countries to meet low-carbon energy targets with power systems that avoid damming high priority rivers (e.g., those that would cause conflicts with other social and environmental benefits) for a similar system cost as status quo approaches. We also show that, through reduction of risk and potential conflict, strategic planning of hydropower site selection can improve financial performance for investors and developers, with a case study from Colombia.