The value of improving freshwater ecosystem services: South Carolina residents' willingness to pay for improved water quality.

Riverine ecosystems play a crucial role in providing essential services such as drinking water, food, recreation, and other aquatic resources. Yet, their capacity to deliver ecosystem services is threatened by rapid land use which modifies their ecological functions. While freshwater monitoring and restoration programs became more robust with technological advancement, the technical ecosystem indicators monitored by experts do not typically resonate with the public. Since public sentiments and preferences are crucial in conservation planning, we quantified households' mean willingness to pay (WTP) for riverine ecosystem services in South Carolina (SC) using a payment card approach. This technique in conducting a contingent valuation method allowed us to estimate mean WTP for five aquatic indicators. Findings revealed that households' monthly mean WTP is higher for indicators that can enhance recreational benefits, such as fish catch ($5.89- $6.58), species richness ($6.28- $6.72) and access ($6.75) compared to IBI ($5.74- $6.26) and instream flow quality ($5.34-6.06). When extrapolated to entire SC, the improvement of each indicator would translate to total benefits ranging between $131 to $165 million annually. The values computed from this study could serve as inputs for the computation of benefit-cost ratios of proposed freshwater programs. By incorporating households' WTP in the policy analysis, decision makers can prioritize programs that offer the greatest public benefit, while enhancing freshwater quality across the state.