SEA-FISHERIES LABORATORY. 153 
and Mr. Durlacher was of opinion that Aberamffra was 
an unsuitable place for a tank. But on consideration of 
all the facts I do not think the risk of pollution will be 
significant provided that certain alterations in_ the 
existing sewerage can be carried out. Mr. Durlacher 
suggested that Penrhyn Point and its neighbourhood was 
the best place in the Estuary, but while this may be so, 
it will probably be found that this place is inconvenient 
for the fishermen, who will then refuse to use it. The 
risk taken at Aberamffra is that from the sewer in the 
harbour and from the drains at the houses on Aberamffra 
Cliff. Now the sewer in the harbour ought to be 
repaired, and it does not seem a difficult task to connect 
together the separate drains from Aberamffra Cliff and 
_ arrange that they discharge by a single outfall on ebb- 
tide only. It seems to me to be an easy task for an 
engineer to arrange a flap at the mouth of the outfall 
sewer, worked by a buoy which will open the flap when 
the tide is ebbing and close it when the flood stream 
begins. These two changes in the existing sewerage 
would probably prevent any serious contamination of 
Aberamffra harbour. 
Further Mr. Durlacher’s results show that there is 
a great rise in the density of the water at Aberamfira 
between low water and high water—a rise very similar 
to that at Aberdovey. This indicates a very considerable 
dilution of estuarine water by open sea water, and 
encourages us to think that water taken at about the time 
of full flood will be practically uncontaminated. 
‘No water samples were taken at Aberamffra, for 1t 
was found that there were plenty of small mussels on the 
rocks at the place where the tank is to be constructed. 
Two series of samples of these mussels were taken, and 
estimates of the contained sewage bacteria were made. 
