8 BULLETIN 217, U. S. DEPARTMENT OF AGRICULTURE. 



migrants gathering from near-by breeding grounds to feed, molt, 

 and pass the early fall in the accustomed security of the great marshes. 

 Large numbers of the birds found dead in July and August un- 

 doubtedly have come to these marshes from other localities. In the 

 brief account given of the history of the trouble it was shown that 

 sick birds have occurred for a longer time than is commonly believed- 

 In fact there can be little doubt that for many years under certain 

 conditions a few sick birds have been present annually in alkaline 

 pools and on mud flats bordering the mouths of the rivers. The sudden 

 increase in the mortality may be explained by the increased amount 

 of water used for irrigating purposes. Undoubtedly the quantity of 

 water reaching the lake through the rivers has been greatly reduced 

 within the past 15 years. Alkalis and salts are leached from the soil 

 by irrigation and carried off in the drainage to be deposited in the 

 deltas of the rivers and elsewhere. An instance of this leaching is 

 shown in the freshening of the ground water north of Bear River near 

 Corinne. Under these changing conditions disaster came with the 

 dry summer of 1910. 



SUGGESTED REMEDIES. 



Fresh water is the only remedial agency yet discovered for dealing 

 with this mortality among waterfowl. In the marshes at the mouth 

 of the Jordan River the problem may be considered as settled. 

 Water from the Jordan is carried through the marsh in a series of 

 canals, and as long as it is abundant these are kept full. When the 

 supply fails, as it may in dry years, the marsh can readily be drained 

 and dried. Under normal conditions there are only two points in 

 these channels where stagnation and consequent mortality may occur 

 to any extent; namely, near the Mallard Holes and about the Duel: 

 Puddles on the west side. On the flats below the dams on the lake 

 front a small number of birds will undoubtedly die, even though the 

 marshes are drained, but under present conditions this can not be 

 remedied. 



At the mouth of the Weber River the situation is more difficult. 

 Here the north channel at present marks the true course of the 

 stream, though in late summer there is little water, as the whole 

 supply is diverted near Ogden for irrigation purposes. Toward the 

 lake are level flats with shallow pools of water connected by a very 

 slight current, or cut off in places from the main body. The south 

 channel has higher banks and runs as a narrow stream supplied by 

 waste water from irrigation ditches. Few, if any, sick birds occur in 

 this channel, as it is deeper and well drained. However, the ducks 

 elect to use the shallow flats along the north channel, and probably 

 less than 10 per cent of the birds that gather there during the summer 

 are alive by the opening of the shooting season on October 1 . If the 



