The infrastructure links the historic village of Meelick in east Galway to Lusmagh in west Offaly and forms part of the Hymany Way and the Beara-Breifne Way walking trails.
The weir was built in the 1840s as part of the Shannon Navigation. More than 300 metres in length, it has a 12-sluice barrage and maintains and regulates the navigation level for the section of the waterway between Athlone (Lough Ree) and Meelick (Lough Derg).
The weir was damaged in severe storms in 2009 and again in 2015/2016, when the walkway was also damaged and was subsequently closed.
Construction work on the €3.2m Waterways Ireland project began in 2019 and included the restoration of the weir, its 300m walkway and new tilting weir gates, along with other weir refurbishments.