Estimating the non-market benefits of water quality improvement for a case study in Spain: A contingent valuation approach

This article addresses an important topic related to the application of the European Water Framework Directive (WFD) in Spanish watersheds. Results on a contingent valuation study, aimed to assess the non-market benefits of water quality improvements in the Guadiana river basin (GRB), are shown. Special attention has been paid to the issue of zero willingness-to-pay (WTP) responses, while addressing the possible presence of self-selection caused by protest responses. The results (i) indicate that sample selection bias is not a problem in our application, (ii) allow us to identify some key determinants of voting behaviour, and (iii) through the use of different econometric models allows us to find a robust estimate for the mean WTP to accurately inform decision-making. (C) 2012 Elsevier Ltd. All rights reserved.