*2.2. Interviews*

Semi-structured interviews were conducted after the questionnaires were collected to obtain a more comprehensive understanding of the perspectives of different interest groups. These semi-structured interviews were flexible and allowed interviewers to alter the pace and order of questions depending on interviewees to acquire their best responses. The interviewees were communicated via social media, informed about the purpose of the study, and asked if they would be willing to participate. Three SHP owners, a county government administrator, a provincial governmen<sup>t</sup> administrator, as well as a hydro-ecology engineer agreed to join. The three SHP owners and the administrator were involved in pilot work for this project in 2014. One owner had previously retrofitted his facility with sluices and installed an ecological generator, and the other two owners had their projects decommissioned. The administrator had long-term experience in SHP management. The hydro-ecology engineer was selected as a representative member of the public. Interviews were recorded when permitted. The semi-interviews lasted 20–40 min and covered details of the SHPs of the interviewed owners as well as attitudes and perspectives on the challenges of E-flows implementation. The questions for SHP owners, the administrator and the engineer consisted of 6 close-ended questions and 3 open-ended questions; 3 close-ended questions and 3 open-ended questions; and 2 close-ended questions and 4 open-ended questions, respectively. Those questions covered attitudes and perspectives on the challenges of E-flows implementation and the issue of "who needs to pay for the losses" (see Tables S2–S4).

### *2.3. Secondary Data Collection*

Secondary sources were used to determine environmental impacts as well as the losses in electricity production caused by E-flows implementation and the average returns of SHPs. Sources included the SHP Annual Statistical Report (2016) in Fujian Province and the 2017 Survey report on the status of rural hydropower projects in Fujian Province. Information and data were also obtained from the Fujian Provincial Department of Water Resources.
