 The banks of the reservoir are listed as a Site of Special Scientific Interest (SSSI) due to the diversity of waxcap fungi discovered growing on them.WPD appealed against this listing stating the Countryside Council for Wales's (CCW) decision was 'premature, arbirtrary and unfair', but in January 2007 a High Court Judge upheld the SSSI designation and said it was 'an important site'.The reservoir was also listed by Cadw in July 2009 as a building of special architectural or historic interest, despite an appeal from WPD against the listing.