Barriers identified by fisheries staff, and by targeted surveys of likely barrier locations based on desk studies of channel topography for this study. The locations of long-established barrier sites (four major hydro-electric schemes) for the Liffey, Lee, Shannon and Erne were not marked, although habitat upstream was identified as a non-self sustaining salmon channel. Barriers were identified for the 2003 wetted areas study.  McGinnity, P.,Gargan, P.,Roche, W., Mills, P. & McGarrigle, M. 2003. Quantification of the Freshwater Salmon Habitat Asset in Ireland using data interpreted in a GIS platform. Irish Freshwater Fisheries, Ecology and Management Series: Number 3, Central Fisheries Board, Dublin, Ireland. REST (JSON)