EFFECT OF REMOVING DAMS. 43 
hand, the value of the fishery in ten miles of river above 
the weir was at that time only £30 a year. 
After the reconstruction of the weir the fisheries again 
began to decay, and twenty years later the value of 
Trostrey fishery, including the rent of a considerable 
mill, a house and garden, and a few acres of wood for the 
repair of the weir, had fallen to £27 a year. Some local 
gentlemen, forming themselves into an association for the 
improvement of the fisheries, rented and lowered the weir 
at Trostrey, and made several openings in the body of the 
dam through which the salmon could pass at almost any 
state of the water. The result was that scores, “and in 
some instances hundreds,” of fish were taken with the rod 
‘in the neighbourhood of Crickhowell and even higher up, 
whereas formerly “there was hardly a salmon taken all 
the summer” above Trostrey weir at all. The seed thus 
sown has borne abundant fruit, and the salmon fisheries of 
the Usk, under careful protection, have so improved in value 
that, though the river is injuriously affected by town 
sewage, though three of its largest tributaries are abso- 
lutely ruined by pollution, and several others are more or 
less blocked by weirs, it produces on an average 10,000 
fish a year, 1,500 of which are taken by anglers. 
Of course, it is not possible to treat all obstructive weirs 
in the same summary manner as Bywell and Trostrey. A 
mill or a manufactory worth hundreds or thousands a year 
cannot be destroyed for the sake of a fishery non-existent, 
or of insignificant value. If our predecessors had foreseen 
the effect that weirs would have had on many a prosperous 
fishery, they might have hesitated before sacrificing a 
certainty for an uncertainty ; they could at any rate have 
taken means to prevent the future industry from destroying 
the existing one, and fisheries which are now conspicuous 
