The World Bank's Operational Directive on Environmental Assessment was approved in 1989, and expanded in 1991. It is the principal mechanism for taking account of the environmental effects of the Bank's project lending. All prospective Bank projects are screened for potential environmental effects and classified into categories. For instance, category A groups projects with potentially serious environmental damage and require complete Environmental assessments (EAs). Several A category projects have been modified as a result, including re-routing a channel to avoid disruptions to a lagoon, for the Lower Guayas flood control project in Ecuador.