National surveys of Irish rivers have taken place on a continuous basis since 1971, when 2,900 km of river channel was surveyed. The National Rivers Monitoring Programme was replaced by the Water Framework Monitoring Programme from 22 December 2006. As part of the Water Framework Directive (WFD) Monitoring Programme approximately one third of our major rivers and their more important tributaries are surveyed and assessed each year by EPA ecologists. A complete survey cycle is completed every three years. The sites are scored on a five point system developed by the EPA called the Biological Q rating system.