REPORT OP THE FJSIJ AND GAME COMMISSION. 61 



whole, the screen work has been very successful, considering the number 

 of ditches and canals that we have had to handle and the great differ- 

 ence in conditions that prevail in different parts of the state. 



Pollution of Streams. 



The pollution of the inland streams by sawdust, slimes from the mines, 

 and other waste matter polluting the streams, has been given attention 

 whenever reports have been received. We have not had any serious 

 trouble with any of the cases handled, although numerous complaints 

 regarding stream pollution by mining operations are received. Many 

 reports come from the old mining districts where the fish were destroyed 

 in the early history of mining operations in this state and no further 

 damage can be done. Wherever new plants are reported we insist that 

 all the slimes be impounded in storage reservoirs or vats until the 

 heavier material has settled. 



The flotation process of working ores has given us considerable 

 trouble, as the pulp is so fine that it is very difficult to settle, remaining 

 in suspension in the water for weeks. The damage that it does to the 

 fish is very slight if the plants are not too large. We are giving this, 

 one of the latest processes of handling ores, special study, for this 

 method will probably be used extensively in nearly all mining operations 

 in the future. 



Propagation of Shad. 



Early in the season of 1916 the question of propagating shad was 

 taken up by the department. The heavy fishing for shad in the bays 

 and in the Sacramento and San Joaquin rivers for the last few years 

 had caused noticeable falling off in the numbers of these fish and to 

 keep the supply up it was deemed necessary to resort to artificial 

 propagation. 



About the same time we received a request from the Massachusetts 

 and Connecticut Fish and Game eommi.ssions requesting the California 

 commission to collect shad eggs from California waters and ship them 

 to their hatcheries, as they werQ desirous of restocking the depleted 

 waters of the Eastern states with shad. Shad were introduced into 

 California by the California Fish Commission in 1871. They increased 

 rapidly until a few years ago the Sacramento and San Joaquin rivers 

 were fairly alive with them in the spring and summer when the run 

 of shad was at its height. 



The excessive fishing and pollution of the Eastern rivers has caused 

 the shad to become very scarce and it was the desire of the Massachu- 

 setts and Connecticut commissions to restock their waters. We agreed 

 to collect the shad eggs for the two connnissions, as it was considered an 

 opportune time to carry on experiments to locate the spawning places 



