54 



larger rivers, such as the Taunton and the Merrimack, which 

 receive a liberal amount, together with trade-waste pollution, 

 it has a most disastrous effect. Unfortunately, in these cases 

 we cannot accurately determine the relative influence of each. 

 The following rivers receive an appreciable amount of sewage: 

 Merrimack, Ipswich, Danvers, Saugus, Mystic, Charles, Ne- 

 ponset, Weymouth Fore, Weymouth Back, Acushnet, Taunton 

 and its tributaries. 



Trade Wastes. — Among the injurious trade wastes entering 

 our alewife streams are acids, alkalies and miscellaneous chem- 

 icals from nail and iron works, rubber factories, wool-scouring 

 establishments, bleacheries, laundries, dye works, leather fac- 

 tories, etc. Sulphuric acid, which is extensively used in the 

 scaling process of the nail factories and iron works, in the rubber 

 factories, and in wool-scouring establishments, causes the death 

 of fish in a dilution of 1 part in 160,000, and interferes with 

 their migration in far weaker dilutions. On Jones River an 

 instance is reported where alewives held in a fish trap were 

 killed by the waste discharge of the nail factories. The waste 

 products of bleacheries, laundries and some manufacturing 

 plants contain appreciable quantities of alkalies. Previous to 

 the installation of filter beds and an alkali reclaiming machine 

 at the New Bedford and Agawam Finishing Company on the 

 Agawam River, East Wareham, dead alewives and shad were 

 not infrequently found (Fig. 9). The company has established 

 a method of removing alkalies from the waste products at a 

 substantial saving. By means of settling basins and filter 

 beds the waste products gradually enter the river in a less 

 harmful form as a dark-brown liquid, which Hows along the 

 right bank 125 feet before mingling thoroughly with the stream 

 (Fig. 10). During a run of alewives the fish were observed, 

 upon reaching this material, to swerve to the opposite bank of 

 the stream as if the substance were distasteful to them, but it 

 did not seriously interfere with their spring run. Results have 

 proved fairly satisfactory as long as this system has been ad- 

 hered to. 



The waste products of woolen mills, which contain a mixture 

 of dyestuffs and chemicals, are the most numerous forms of 

 pollution. The extent of injury from this type, although con- 



