of Templeogue in 1456, and a Walsh in 1491. The Tongue or Stone Boat, dividing the flow 2:1, was agreed to be maintained, and the city was to pay for any related works required on the monastic weir on the Dodder. St Thomas's Abbey was to receive one mark for the agreement, and an annual rental of five marks, though records show that payments were delayed or not made on occasion. Further, the officials of the city were allowed to gather citizens, and tenants of the religious settlements, to repair the weir, channels and dividing structure, and it is recorded that the Tongue was rebuilt in 1555. There were also deliberate acts of interference with the water supply. In 1534, rebels following Silken Thomas broke the supply lines in an attempt to help his cause, and in 1597 the Talbots of Templeogue blocked the flow in a dispute with mill-owners using its power, an act repeated by Royalist forces during the English Civil War to leave the Cromwellian forces occupying Dublin short of both water and milling capacity for food production. Reputedly a later landowner in Templeogue, Sir Compton Domville, threatened to do the same if a nephew convicted of murder was executed; the threat was not tested, as the aristocrat in question, Lord Henry Barry, had his sentence commuted to banishment. There were also issues with mill operators and landowners near the watercourses taking more water than they were entitled to, some even constructing impromptu sluices by cutting openings in the banks, temporarily closed with earth but easily opened for irrigation purposes. Legislation to manage the Poddle supply included rules forbidding dumping into the watercourses, or washing clothes in them, and grazing of animals alongside, for the latter of which a fine per animal per day could be levied. Following the first known reports of what would nowadays be called industrial pollution, in 1718, an investigation traced the source to a paper mill and a tuck mill, and an initially successful legal defence by the millers led to the passage of An Act for cleaning and repairing the watercourse from the River Dodder to the City of Dublin, and to prevent the diverting and corrupting the Water therein, which gave Dublin Corporation much greater authority over the Poddle and City Watercourse, and banned tuck and woollen mills from the system. Succession and replacement The Abbey of St Thomas was