A mixed-methods assessment of the influence of palm plantations on water resources of indigenous communities of Indonesian Papua

Oil palm expansion in tropical rainforests actively degrades downstream water quality, placing the livelihoods of river-dependent Indigenous communities who rely on these rivers at greater risk. For the Kaiso, an Indigenous group in Indonesian Papua, the river serves as the primary source for consumptive use, and the plantation impairs access to clean and safe drinking water sources. Seasonal uncertainties, coupled with failed water interventions and planned oil palm expansions, suggest a further deterioration of the health and well-being of the Kaiso through long-term exposure to contaminated water. This study employs a mixed-method approach, integrating quantitative household surveys and qualitative interviews, to examine the current impact of oil palm expansions on community-level water access. The objective is to provide a comprehensive understanding of livelihoods, state interventions, and safe water perception following plantation establishment, corroborated by quantitative findings with water preferences. Results reveal a significant shift towards rainwater for drinking water use, or approximately 85.6 % of households, post-establishment of oil palm plantations. While perceived water quality strongly correlated with non-consumptive use, consumptive use showed no association, suggesting reliance on contaminated sources during dry periods. This necessitates further qualitative investigations. Seasonal uncertainties surrounding rainwater harvesting and failed interventions have obscured the definition of safe water for the Kaiso; boiling was perceived to eliminate all chemical and harmful substances from oil palm plantations, not just biological ones, and needs further assessment. Addressing clean water access faced by Indigenous communities requires a watershed-wide assessment and community participation in plantation-related decisions, particularly for lowland and river-dependent populations, especially in Indonesian Papua.