360 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



polluted. For an hour before low water the sewage 

 probably does not pass out to sea and must be 

 carried up the river with the next flood. A considerable 

 volume of polluted water must then simply oscillate 

 up and down the upper reaches of the river, and some of 

 it must pass out on every tide over the mussels at the 

 mouth of the channel. 



The population of the Borough of Conway is about 

 5,000. Taking the usual constant of water supply of 25 

 gallons per head for 24 hours, we find that 125,000 gallons 

 of crude sewage is discharged per 24 hours — an estimate 

 which does not include the contribution from the popula- 

 tion further up the river. 



It was suggested to us during our first visit that the 

 sewage from Llandudno might possibly affect the Conway 

 area. At Llandudno there are three outfall sewers which 

 open out on the foreshore to the South of Great Orme's 

 Head. Two of these outfalls discharge rain and surface 

 land water, and need not be considered. The third conveys 

 the sewage of Llandudno. It consists of two iron pipes 

 which pass out over the sands, supported on piles, to a 

 buoy which is at low-water mark of ordinary tides. These 

 two pipes are connected and have a single outfall. They 

 are shown on the Admiralty Chart (Holyhead to Liverpool 

 — Western Sheet), but I am informed that about two 

 years ago the lower end of the pipe became sanded up, 

 and about 150 yards were added to the length. When I 

 saw this outfall there were absolutely no indications of 

 sewage matters on the foreshore as far down the length of 

 the pipe as we could go. Automatic valves at the end of 

 the pipe and at the penstock chamber at the beach end 

 open and close when the tide turns, not merely when the 

 end of the pipe is bared or covered, but when the stream 

 changes. The sewage is thus discharged only on the ebb 



