49 



The mere presence of dams is not dangerous. Only when 

 they are unequipped with fishways, or are not opened during 

 the spring run, do they become a menace. Properly supplied 

 with adequate passageways, dams would never have exerted 

 a pernicious influence upon the alewife fishery. In nearly all 

 instances the laws contained specific provisions for fishways in 

 dams, but frequently these provisions were modified or repealed 

 through the influence of the mill owners. 



Dams have proved injurious to the alewife fishery by the 

 direct obstruction of the passage of the fish to the spawning 

 grounds, even when the gates are raised at certain seasons, for 

 the reason that the sill of the dam, the lowest point to which 

 the water may be lowered, is too high above the natural level 

 of the stream, thus rendering difficult or preventing the advance 

 of the alewives. This latter condition is especially prevalent in 

 the small cranberry dams, which the owners usually open dur- 

 ing the spawning season to permit the run of alewives. 



The return of the young alewives to salt water in the fall 

 presents a separate problem. At this season there is a minimum 

 flow of water, scarcely sufficient for power or other mill pur- 

 poses, and little water passes over the spillways. The young 

 alewives following the main flow of water are carried into the 

 flumes and through the mills, where according to general 

 opinion, they are destroyed in the turbine water wheels. As 

 yet no experiments have been made to determine the per cent 

 of fish destroyed in passing through different types of water 

 wheels, but until more definite information is forthcoming the 

 best policy is to screen the flumes and furnish a passageway 

 down stream at a minimum expense of water. 



Impassable dams have undoubtedly been the immediate cause 

 of the decline of many fisheries, and a direct relation can be 

 shown between the number of impassable dams on a stream 

 and the condition of the fishery, e.g., Indian Head River, Mer- 

 rimack River, Ipswich River, Weweantit River and Acushnet 

 River. The old laws regarding dams were well adapted for the 

 protection of the fishery, the decline of which was not due to 

 a lack of good laws, but rather to the. non-enforcement of exist- 

 ing legislation. The only remedy for an obstructing dam is 

 the installation of a passable fishway, with which every dam 



