24 The Mourne Water Scheme. 



In Belfast the average rainfall in the year, taken from the 

 gauge at the Queen's College, was some 34 or 34^ inches, but 

 in the neighbourhood whence it was proposed to take the 

 water — some 1,500 feet above the ordnance datum of low water 

 — it was much more. For instance, in the past year, which, as 

 they knew, had been a dry one, the rainfall in Belfast had been 

 28 inches, while on the mean level of the proposed catchment 

 area it was 54 inches. Allowing 1 5 inches as a margin for 

 waste there would be 39 inches left as water which might be 

 collectable. A further deduction, however, must be made for 

 very heavy floods, the water of which could not be stored. 

 Therefore a calculation was based on a rainfall of 28 inches, 

 which gave something like 16,000,000 or 17,000,000 gallons 

 per day. The gross consumption in Belfast at present was 

 from 10,000,000 to 10,500,000 gallons per day, so that the new 

 supply would enable the Commissioners to satisfy the wants of 

 a population more than double that of Belfast at present. But, 

 in addition, other catchment areas adjacent might be taken in 

 if occasion arose, and a supply of water amounting to 30,000,000 

 gallons a day could be brought into the city. So that, though 

 the scheme as at present contemplated was an ample one for all 

 estimated future wants, it was also an expansible one which 

 could be made to meet the most severe demands upon it due to 

 the rapid growth of population during the next half century. 

 The character of the district was one well suited to the pur- 

 poses of a water supply. The slopes generally are steep, and, 

 though there are patches of bog, one of the worst of these 

 patches was excluded from the area over which the Commis- 

 sioners had taken control. The water, however, might be 

 slightly coloured by peat. But, judging from results, it seemed 

 as if the sand carried down from the higher levels, which were 

 particularly sandy, acted in the course of the water in such a 

 way as to carry the peat down and subside it. In a valley 

 called the Happy Valley, or Silent Valley, it was proposed to 

 construct a large reservoir. This reservoir would be about two 

 hundred acres of water surface, seventy feet deep against the 



