The most recent legislative basis for the navigation’s water supply is the 1986 Canals Act, of particular reference is Section 6 set out below.
Powers of Commissioners
6 – The Commissioners shall have all powers as are necessary for the performance of their functions under this Act and shall without prejudice to the generality of the foregoing, have power to undertake the care, management, control maintenance, repair, improvement and development of the canals and other canal property and to –
(a) Draw any water necessary for the purposes of the canals from any source whatsoever from which the Board was entitled to draw such water before the vesting day, whether by virtue of any enactment or otherwise;
(a) Dredge, widen, deepen, alter the course of or otherwise improve the canals or improve the supply of water for the canals and for that purpose to dredge, widen or deepen any stream, river, drain or channel carrying any such water supply and replace or repair any pipe carrying any such supply;
(b) Construct, alter, underpin or improve any lock, quay, harbour, drydock, weir, fishpass, slipway, pumping station, building, towpath, bridge, aqueduct, embankment, culvert or road (other than a public road within the meaning of Local Government (Roads and Motorways) Act, 1974) on, over or beside the canals;
(c) Acquire and dispose of any land or any easement or other right over land and may, if necessary, in accordance with the Second Schedule. Acquire compulsorily any land or any easement or other right over land;
(d) Alter the water levels of the canals without prejudice to the right of the Board or any other person to receive water from the canals;
(e) Close to navigation any part of a canal not required for navigation and reopen and declare navigable any part of a canal previously closed to navigation
(f) Lease or let to any person canal property and license the use of the canals and canal water by any person.
Given the historic nature of Waterways Ireland’s water supplies for navigation, these (water abstractions) are not mapped nor are the volumes recorded. The volume of water required varies by season by availability of water in a supply, demand depends on volume of traffic, weather, etc.