Decision rules for salt –feedback loops in One Water systems and their implications for collective management

Freshwater salinization is an emerging challenge that threatens ecosystem health and drinking water security. Coordinated action is necessary to address this challenge, but is often hampered by fragmented management of water subsystems that does not consider the feedback loops between them. This study uses surveys, interviews, and fuzzy cognitive maps (mental models that capture important system concepts and relationships) to characterize stakeholder perceptions of feedback loops between water subsystems and their implications for salt management. We use Virginia’s Occoquan Reservoir, a salinizing “One Water” system where wastewater, drinking water, and stormwater are coupled and the need for integrated management is great, as a test case, focusing on (1) the prevalence of feedback loops in stakeholder mental models of salinization, (2) the existence of decision rules - feedback loops that bridge social and natural subsystems and constitute potential levers for managing salt, and (3) the extent to which aggregating multiple mental models generates “wiser” decision rules. Our results suggest that while stakeholders perceive relatively few feedback loops and decision rules individually, collectively they resolve a dynamic and interconnected system. Aggregating multiple perspectives revealed over 450 decision rules, not all of which made sense to individuals. Sense-making depended more on the content of decision rules than their length or dynamics. Stormwater subsystems were absent from all decision rules, highlighting a gap in systems understanding that could hinder effective management. Creating opportunities for cross-agency communication and shared learning could help bridge such gaps, supporting collective governance in One Water systems like the Occoquan. • Social-ecological feedback loops capture decision rules for managing salinization. • Decision rules are rarely recognized by individuals but emerge in aggregate. • Not all decision rules make sense, reflecting misspecified processes and bias. • Emergent rules bridge wastewater and drinking water subsystems, but omit stormwater. • Cross-agency communication/learning is needed to support collective salt management.