Mortalities in salmonid populations induced by Chondrococcus columnaris are usually associated with warm river water temperatures. Increasing use of the Columbia River for agriculture, industry and power will introduce additional added heat increments which could result,in additional growth of C. columnaris and proliferation of the disease. It is necessary, therefore, that we examine the existing environmental factors which contribute to the disease in the river. Proliferation and release of C. columnaris from fish ladders was demonstrated by the large number of organisms isolated from the Rocky Reach fish ladder on the Columbia River during 1965. The authors found that C. columnaris release into the water was related to the high incidence of infected coarse fishes and anadromous salmonids in the ladder. In this report, we will describe results which suggest that fish ladders may be important, sites for transferring the disease from fish indigenous to the Columbia River to migrating anadromous salmonids.