18 American Fisheries Society 



of the water; the stream is being utilized for power. The result 

 of that can be seen very clearly when one examines such a place 

 as the upper Hudson. The sulphide wastes from a mill at the 

 upper end of the series of sulphide mills have accumulated in a 

 basin behind a big power dam until this upper lake has a bottom 

 covered with polluted material and without the evidences of 

 life characteristic of clean and unpolluted water. Where the 

 water comes over the dam — or through the wheels, as it mostly 

 does — it shows evidence very clearly of its polluted character 

 as it starts down over a long series of riffles below the dam. You 

 can see in the lack of the organisms characteristic of free water 

 and in the presence of organisms characterizing polluted water, 

 that there is pollution in the water near the dam; if you follow 

 the current down over the riffles the organisms of pollution grad- 

 ually disappear, the organisms that are in free water gradually 

 appear until you come to the next relatively still waters, of Big 

 Bay as it is called, above Glens Falls, where you get a rich growth 

 of green plants and all other conditions that indicate pure water. 

 In that stretch of the river there is splendid fishing. It is in 

 passing Glens Falls, Hudson Falls and Fort Edward, with their 

 numerous sulphide mills, that the water accumulates its pollution 

 again, and below Fort Edward it has just the character that was 

 manifested in the polluted basin higher up, only in more con- 

 spicuous and extreme fashion. These conditions suggest to us 

 what will happen when another dam is built, and one is projected 

 near the foot of the riffles at the head of Big Bay. It will transform 

 the riffles above the site of that dam into a pond. Within that 

 pond the slower movement and the limited contact of the water 

 with the atmosphere will prevent the acquisition of oxygen, will 

 prevent correcting the conditions of pollution, and will transform 

 that stretch of the river also into a polluted basin. And so the 

 building of a series of dams may readily make over a stream from 

 one which is able to purify itself, despite the waste added to it, 

 into one in which such conditions for purification will not exist. 

 It behooves us then to consider the pollution question not merely 

 on the basis of present conditions, but on the basis of probable 

 changes which will accentuate those conditions that are un- 

 favorable. 



