382 THE SALMON RIVERS OF SCOTLAND 



As a salmon river the Girvan has suffered dreadfully from the 

 three worst combinations pollution, overnetting, and obstructive 

 dam-dykes. The Irvine and the Garnock rivers, which have their 

 joint entrance to the sea in the centre of Troon Bay, have been 

 ruined by pollution, and are not mentioned separately in consequence. 

 The Girvan a few years ago came very near to sharing the same fate. 

 In the two rivers mentioned the main source of pollution is from 

 iron works. In the Girvan the pollution has also been iron, but in 

 the form of the sulphate, impregnating water pumped from coal pits. 



It was in February 1902 that the most serious pollution occurred. 

 A large coal pit had, eighteen months previously, taken fire and been 

 flooded and shut down. In the year mentioned the pit was re-opened 

 and a commencement made in pumping out the water. The dis- 

 charge was carried into a burn near Dailly, which was immediately 

 turned a bright orange colour. The burn discharges into the Girvan 

 at a point about 8j miles from the mouth, and so strong was the 

 pollution that every fish from this point to the sea died. The water 

 of the river was like pea-soup. All the kelts which had not 

 descended and attempted to do so perished, and the smolts fell easy 

 victims to the poisoned water when they attempted to migrate in 

 late spring. Clean fish were unable to ascend, and the nets near the 

 mouth of the river had a rich harvest. The pumping was continued 

 month after month, and although six settling ponds were hastily 

 constructed and the effluent treated with lime, little good seemed to 

 result, since pit pumps were throwing more water than could be 

 coped with. The bottom of the burn between the pit and the river 

 became deeply crusted with the iron deposit. I could push rny stick 

 in about half a foot in many places. The result was that the Girvan 

 became void of migratory salmonidae. 



An analysis of the water showed enormous quantities of metallic 

 salts (569 '9 grains per gallon of sulphate of iron). The necessary 

 oxygen of the water was absorbed. Fish were asphyxiated, having 

 no dissolved oxygen to breathe, and, in addition, having their gills 

 clogged with the matter in suspension. The public analysts of 

 Glasgow gave it as their opinion that if the river water, as it then 

 was, were mixed with fifty times its bulk of pure water, fish would 

 still be unable to live in it. 



By degrees the strength of the pollution diminished, remedial 

 measures were entirely abandoned, and the pumps which were 

 working twelve hours daily, and throwing 475 gallons a minute 

 were left to get to the last of the water, and so end the pollution. 



