The non-market benefits of WFD implementation are valued in one of the largest river basins in Portugal.
Tests are carried out for sensitivity to scope and scale.
Public WTP for incremental water quality improvements declines once GES is achieved.
Respondents living outside the river basin value water quality improvements significantly less than respondents living inside the basin.
No spatial heterogeneity is found inside the river basin and public WTP for the Mondego estuary and river basin is the same.