There is abundant landscape evidence for extensive land reclamation conducted within the Shannon estuary wetlands. To date, little published research is available which identifies how much reclamation has occurred, its timing and the likely environmental implications. This paper addresses these questions on the basis of available cartographic and documentary data on land reclamation in this area. Identification of reclaimed land was based on the 2nd Edition Ordnance Survey of Ireland Map Series of 1924. These maps represent landscape features relating to reclamation, such as embankments, artificial arterial drainage channels and sluices. Using such indicators for the purpose of demarcation, the extent of the lands reclaimed has been mapped. Documentary information on reclamation schemes was acquired from the National Archives files on the Irish Quit Rent Office, including letters, memoranda, draft bills and Government Acts, legal documents and statements of account, and these support and supplement cartographic data.

In total, approximately 6,500ha of the Shannon estuary lowlands were reclaimed for agriculture and other purposes. This has significantly altered the morphometric characteristics of the estuary, as embankments and revetments for flood protection have reduced the potential energy dissipation area and the water storage capacity of the estuarine wetlands. Reclamation has resulted in modification of the estuarine physical environment and its hydrodynamics, and altered the character of the wetland habitat in the estuary environs.