Then an exceedingly important step was taken, which was the foundation and immediate cause of all the measures which have since been adopted, which was the project for opening the navigation of the Shannon, and draining the adjoining lands.
The primary object of that great work was opening the navigation, but it was put forward as a secondary object to improve what are called the Callow Lands, bordering on the Shannon, that is the alluvial lands adjoining the river, which ought to be valuable meadow lands, and which, properly improved, would be extremely valuable, but which in the then unimproved and neglected state of the river were annually overflowed for several months in the year, and were rendered of little value, affording only occasional pasturage, and uncertain crops of coarse grass.
That was a secondary object of the Shannon works; and the Shannon undertaking was founded on a compromise between those two objects,
namely, between the navigation and the drainage.
The point endeavoured to be attained was, to have the greatest amount of drainage which was consistent with the improvement of the navigation. That great work was ably carried through, and, in my opinion, was perfectly successful.
I do not mean that it is a perfect drainage work, or a perfect navigation work, but that it is the best compromise between the two that could have been effected, and showed how much could be accomplished when drainage only was the object. But however that may be, it furnished the model for, and gave a stimulus to all that has been done since […].
Evidence of Sir Charles Edward Trevelyan KCB, Assistant Secretary to the Treasury, to the House of Lords Select Committee on the Drainage of Lands (Ireland), on 4 June 1852 in Report from the Select Committee of the House of Lords appointed to inquire into the Operation of the Acts relating to the Drainage of Lands in Ireland, as administered by the Board of Works; and to report thereon to the House: together with the Minutes of Evidence, and Appendix Session 1852 Ordered, by The House of Commons, to be Printed, 22 November 1852 [10]
Irish waterways history 