Where the more stringent water quality requirements of designated pearl mussel populations are not met, action must be taken under the WFD to restore waters to the required condition within a prescribed timeframe. In 2009, the DoEHLG released regulations on the freshwater pearl mussel. The regulations i) set environmental quality objectives for the habitats of freshwater pearl mussel populations, ii) set out the duties of public authorities with respect to achieving the objectives, and iii) require the formulation and implementation of sub-basin management plans and related measures.