WATER CONSERVATION 95 



as affecting the value of the water as a habitat for animal life. Sur- 

 prisingly interesting observations and inferences have been made, but 

 nothing has been learned to gainsay the statement that, to realize any- 

 thing like the potential abundance of fish-life in our streams, it is neces- 

 sary to approach more nearly to a condition of stable equilibrium. The 

 primary difference between a natural stream or pond and an artificial 

 fish-cultural pond is that in the latter the conditions are relatively stable 

 and subject to a degree of control. 



It is not to be supposed that water-power development has no rela- 

 tion to fisheries except as expressed in the presence or absence of a fish- 

 way. It may be inferred from what has previously been said that arti- 

 ficial pools at intervals in the course of a stream, entirely apart from 

 the question of flshways, may bring substantial advantages in provid- 

 ing relatively extensive feeding and breeding grounds for fish, in af- 

 fording conditions of relative stability, and in tending indirectly to 

 make more uniform the conditions prevailing in the streams below or 

 between the pools. 



It becomes increasingly clear that all matters affecting the flow of 

 streams have the most vital bearing upon the promotion of fishery re- 

 sources, as touching reproduction, nourishment and respiration. 



The artificial propagation of fish, even under present conditions, is 

 producing results of significant value; but it is no disparagement of 

 such operations to venture the prediction that the future will show that 

 the effective conservation of fishery resources depends upon the coup- 

 ling of intelligent fish-culture with comprehensive and well-advised 

 conservation of the environment favorable, both to the natural propa- 

 gation of fish and to the multiplication of the essential elements of 

 food supply. 



The requirements of reasonable brevity prevent our enlarging upon 

 the relation of fisheries to the various other phases of the general 

 scheme of water conservation. Just a few suggestions may be ventured. 

 It has been advocated in at least one state that the reclamation of over- 

 flowed lands should be so administered as not to eliminate entirely 

 the favored breeding grounds of many species of fish. It would seem 

 possible so to coordinate the two objects of retaining "fish-preserves" 

 and providing lateral storage basins for flood waters as to promote 

 simultaneously the conservation of fish and the prevention of floods. 



In the irrigation fields of the west, it appears that there is not only 

 a neglect of the possible advantages for fish life, but an unfortunate 

 waste of the existing fish resources, owing to the want of suitable pro- 

 tecting screens in the irrigation laterals. The opportunities and the 

 needs are not, however, unrecognized, and the subject receives serious 

 consideration in some of the states concerned. 



Stream pollution by sewage or industrial wastes has the closest re- 



