SEA-FISHERIES LABORATORY. 449 



one must assume that, at other times than the holiday 

 season, when there is no bathing in the estuary, the 

 sewage may be liberated at any state of the tide that 

 permits of the discharge; and, further, that in varying 

 conditions of tides and winds and sea the direction of 

 flow may be otherwise than that stated.* 



At low water the width of the open channel is not 

 great. It varies from about 600 to 700 feet between 

 Aberdovey and the bar, and from about 600 to 300 feet 

 between Aberdovey and Trefri. The depth of water is 

 also very little. At low water it is not much more than 

 about one fathom on the bar, and the greatest depth in 

 the channel is five fathoms, about half a mile west from 

 Aberdovey. Between the bar and the pier the average 

 depth at low water is only about two fathoms, while 

 between Aberdovey and Trefri it is, on the average, less 

 than one fathom at low water of spring tides. The 

 volume of water in the channel is therefore not very 

 great, and near low water of even ordinary tides any 

 discharging sewage may very easily pollute the water in 

 the shallow channel north from the pier. 



The mussels are found in the channel both east and 

 west from the pier, and they may be obtained in close 

 proximity to the sewer outfall. East from the pier they 

 are mainly found near the north side of the channel, 

 where the bottom is hard. These mussels are of fair 

 size and good quality. West from the pier they are 

 small and badly nourished. It is proposed to transplant 

 mussels from the seaward side of Aberdovey to the 

 channel at Penhelyg, and further to the east. 



There can be no doubt Hint the mussels from the 

 estuary of the Dovey are polluted so grossly Hint they 

 ought not to be used as human food without sonic pre- 

 liminary purification. They are bacteriologically worse 



♦See the Report, by Mr. V. W. Durluchcr, in this volume, p. 425, 

 on the Drift of Sewage in the Estuary of tin: Dovey. 



