118 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
located. On sand bars in the creek there was found an abundant 
deposit of Copper salts, and a preliminary test demonstrated the pres- 
ence of large quantities of acid, copper, and iron in the creek water 
discharged into the river. It was thought advisable to take advantage 
of the run of adult salmon at the Baird and Battle Creek hatcheries 
for the purpose of conducting a series of tests as to the susceptibility 
of fish to the materials in the water. 
Careful experiments properly controlled established the faet that 
copper sulphate in solution is decidedly injurious to fish life, and 
even in amounts as small as one part to 582,000 parts of water caused 
the death of salmon in a few hours. Other copper salts and free 
sulphuric acid, the produet of mining and allied operations, were also 
injurious, but not so markedly as copper sulphate. The manner of 
death resembled that of the death of fish from simple asphyxiation 
from the products of their own respiration. Questions are raised as 
to the exact role of the salts in causing death (whether absorption and 
resulting poisoning of nerve centers, or peripheral irritation at gills 
and skin, or a destruction of the osmotic function of gills and conse- 
quent asphyxiation), and whether the metal or acid component of the 
salt is the more active agent. 
Copper sulphate is produced at the ore deposits by natural causes, 
and leaches into the drainage of the region. This process has been 
in operation continuously, and is increased upon opening the depos- 
its by the greater oxidation permitted. The extensively practiced 
process of roasting ores produces large quantities of copper sulphate 
and of sulphuric acid, both of which find their way into the drainage, 
which is acid in the immediate vicinity and so heavily charged with 
copper that efforts are made to save it by precipitation in tanks. 
The smelting yields the slag which is turned into the streams and 
which has been popularly supposed to be the chief factor in the 
mortality of salmon. It is comparatively unimportant, however, and 
the smelting process adds but little to the pollution from mining and 
roasting. While the small tributary which carries the drainage from 
the mines investigated is acid and has no fish life whatever, the Sac- 
ramento itself is mainly alkaline. 
There has been for three seasons an undoubted falling off in the 
salmon on the bateching-grounds, while there is not apparent a corre- 
sponding diminution in the fish entering the river at its mouth. 
The case against the mining and allied operations is not proven, as 
it does not yet appear certain that the mortality known to occur is due 
to artificial conditions; and if so due, that these conditions consist in 
the products of mining, roasting, and smelting thrown into the stream. 
Mr. Chamberlain’s summary of the results of his observations and 
experiments is as follows: 
It is well known that during tie past three seasons the salmon run at the 
spawning-grounds has fallen off to a point where the suspension of the fish cultural 
work is threatened. At the same time the fishing at the entrance of the river 
