FORTIETH BIENNIAL REPORT 35 



problems remain to be solved before it can be considered a complete 

 success. 



The most gratifying trend in connection with the fight against pollu- 

 tion is the growing awareness on the part of the public that the State 

 cannot afford to let its streams become open sewers. Only with the support 

 of aroused public opinion can the evils of pollution be corrected. Because 

 of this attitude, offending industries and municipalities are now taking 

 steps to clean up our waters. 



Every year since 1944 the early part of the fall salmon run in the 

 Tuolumne River has been blocked by pollution from the City of Modesto, 

 and various industries in and near Modesto. In 1947 the situation was so 

 bad and so little progress had been made that at the request of the Division 

 of Fish and Game the Attorney General brought suit against the city and 

 the industries. As in 1944, 1945, and 1946, the temporary expedient used 

 was to release water from Don Pedro Dam to dilute the pollution to the 

 point w^here salmon could live and proceed upstream. The court granted a 

 delay in reaching a permanent solution. The city has been making a sin- 

 cere effort to finish an adequate treatment plant before the fall run of 

 1948, but it seems probable that the plant will not be ready for the first 

 part of the season, and that a release of water will be needed in 1948. 



Pollution at Riverbank on the Stanislaus River caught us off guard, 

 and killed the early part of the fall run in 1947. Because better use was 

 made of the inadequate disposal sj^stem at Riverbank, the remainder of 

 the season passed with no further trouble. By rejuvenating this system, 

 the city and industries will probably be able to get through the fall of 

 1948, but an entirely new series of disposal beds will have to be put in 

 service in the near future. 



During the biennium, the salmon runs were satisfactory in all the 

 major spawning streams of the Central Valley except the Mokelumne and 

 San Joaquin Rivers. For example, the combined spring and fall runs of 

 1946 in the American River were estimated by tagging at 39,000 fish, of 

 which 1,700 passed Folsom Dam. The U. S. Fish and Wildlife Service 

 counted 57,000 salmon in the Tuolumne River in 1946, and estimate that 

 in addition about 4,000 fish jumped the dam and were not counted. The 

 calculated run in the Stanislaus River in 1947 was 13,000 fish. The Mokel- 

 umne River run has dwindled because of an inadequate fishway, but this 

 condition has been corrected, as reported above. 



The situation on the San Joaquin River could not be worse than it is. 

 Inadequate water releases from Friant Dam have resulted in near extinc- 

 tion of the salmon run. The winter of 1946-47 was relatively dry, and the 

 U. S. Bureau of Reclamation felt that it could allot no more than 15,000 

 acre-feet of water for the spring run. This water was released in such 

 manner as to be of maximum benefit, but was still so inadequate as to be 

 disastrous. Flows of 100 to 130 second-feet are inadequate during hot 

 weather. Only 6,000 salmon were counted past Mendota Dam in 1947, 

 compared to 56,000 in 1945, and 30,000 in 1946. 



The winter of 1947-48 started as one of the driest on record. The U. S. 

 Bureau of Reclamation announced that no water whatsoever could be 

 spared for salmon ; and in spite of all our efforts, as well as those of sports- 

 men 's groups, the fishing industry, and congressmen to obtain water, the 

 river below Dos Palos remained dry during the time of the 1948 run. As 



