The OPW carries out Arterial Drainage Maintenance to a total of 11,500km of river channel and approximately 730km of embankments nationally. These maintenance works relate to arterial drainage schemes completed by the OPW under the Arterial Drainage Acts 1945 and 1995, whose purpose was primarily to improve the drainage of agricultural lands. The OPW has a statutory duty to maintain the completed schemes in proper repair and in an effective condition. The annual maintenance programme typically involves some clearance of vegetation and removal of silt build-up on an average five-yearly cycle.
In December 2013 and January 2014, the country experienced a number of exceptional storm events which gave rise to widespread flood events and significant damage to flood defences. OPW has prioritised its resources in responding to these events and in repairing, reinstating and strengthening damaged flood defences. This resulted in the postponement of certain scheduled maintenance works. These works have been included in the 2016 works programme and are expected to be carried out in the coming months.