THE DUCK SICKNESS IN UTAH. 17 
The great prevalence of the duck sickness beginning with 1910 
must be attributed to the lessened supply of water in the streams. 
Coupled with this, however, must be other factors not wholly under- 
stood. It seems probable that changes in the water level of Great 
Salt Lake may be prominent among these. Through the courtesy 
of Otis West, of the Engineering Department of the Southern Pacific 
Railroad, there is available a graph showing oscillations in the lake 
level between the years 1850 and 1914. This chart shows a steady 
decline in the water level from 1886 to 1902. From 1902 to the 
beginning of 1906 the water remained about the same, except for 
the usual rise and fall that occurs each year. A rapid rise began 
then, so that the lake at its highest point in 1910 was nearly 8 feet 
above the minimum in 1905. From 1910 there was at first a slight 
drop, then the level was more or less stable until 1914. In 1914 and 
1915 the water lowered again somewhat. 
The soil below the surface in the Bear River marshes is strongly 
saline, and the ground water permeating it is heavily impregnated with 
salts. Though water in the lower channels and bays was fairly fresh, 
a hole 10 to 15 inches deep at the water's edge usually yielded an 
abundance of strongly saline water. The great rise in the lake 
water would, in this region of low elevations, cause a correspond- 
ing rise in the water table of the soil and bring salines in quantities 
to the surface or near it, perhaps for a considerable distance inland. 
Thus poisonous elements might be available in abundance in areas 
where ducks formerly had fed with impunity. The effect of the 
rising salts in the soil is readily seen in the great areas in which the 
rushes have been killed in the lower portions of the marshes that 
border the lake front. In many places there remain of the former 
growths merely the bulbs with short projecting stubs, or again the 
plants may be newly dead. 
Ducks may establish a slight immunity to the alkali when they 
gradually become accustomed to it in di'uted amounts. In the spring 
numbers of sick birds were said to be found in the lower channels on 
Bear River when the birds returned from the south. This was verified 
when many bodies were seen on the banks of the overflows in May 
of 1915 and 1916. These birds must have died during the early 
spring, otherwise the spring water and the ice would have carried 
them away. Following this there are practically no sick ducks until 
the first part of July. If che water rises in May or June a good 
many young avocets and stilts are killed in the salt pools formed on 
the flats, and occasionally sick coots or young ducks are found. In 
May, 1916, there was a curious instance of the way birds seemingly 
exempt from this trouble may be affected. A large flock of cliff 
swallows was driven down to the flats about Duckville by a heavy 
