This article analyses the application of OECD water governance principles to the semiarid region of Brazil. Between 2012 and 2017, the Paraíba River basin (macroscale) and its Epitácio Pessoa reservoir – EPR (microscale) suffered a severe drought. The reservoir came close to collapse in 2017, which led to water use conflicts that were aggravated due to water mismanagement. Four evaluation criteria were considered: policy alignment to the OECD principles, its implementation, on-ground results, and policy impacts. The outcomes indicate water management fragilities, even after 24 years of the Brazilian National Water Resources Policy enactment, and the need for a better water management integration at different scales: National, State, and River Basin. By considering a smaller scale (a basin and its main reservoir), it was possible to observe water governance failures that lead to water crises since the best practices performed by the national agency, at the national scale, have not been verified at the local scale.