Seasonal rivers in East Africa's drylands have become destabilised by climatic disruption and landscape changes. Despite widespread adaptation practices and interventions, recurrent droughts and floods continue to damage the agropastoral livelihoods dependent on these rivers. Few studies have explored how destabilising rainfall, river flows and adaptations have transformed hydrosocial relations among agropastoralists living near seasonal rivers. This paper reports on a case study in the Tiva River Basin in Kenya, exploring how agropastoralists have experienced changing river flows, rainfall and adaptation processes over the past 75 years. Based on storytelling workshops and a survey, we find that river flows and rainfall have been experienced as increasingly unpredictable and damaging. Water's perceived role has shifted from being rhythmic and regenerative to being an erosive force and scarce resource to be captured and mobilised. Adaptation has materialised in multiple forms, each of which has, and continues to, reshape reshape the ways in which water is perceived and used. This requires attention from adaptation research with regard to policy and practice in agropastoral drylands. First, public hydraulic infrastructures inscribe norms for capturing and controlling water, while the limits of their functionality are layered into existing arrangements for accessing water. Second, the spread of private irrigation along seasonal rivers supports adaptation, but is only accessible for a small group and leads to inequalities in water access and adaptive capacities. Third, many agropastoralists pursue bottom-up adaptive practices to retain water, but face various hindrances in sustaining their efforts.