Ecological Consequences of Winter Cloud Seeding

Some ecological consequences of cloud seeding are considered with special reference to winter orographic programs using silver iodide as the seeding agent. It appears that with present technology an operational program to increase winter precipitation in the mountains might deposit about 0.3 g of silver/ha/yr and increase snowfall by 10–20%. The investigation indicates that the silver iodide deposited directly on organisms would not be harmful to them. Moreover, even if silver were concentrated in the upper layers of soil, harmful effects to plants and microorganisms would not be expected for at least 100 years and probably much longer. Snowfall increases of 10–20% are unlikely to significantly affect the vegetation of fescue meadows typical of western Montana, but very large and presently unattainable increase (100–400%) could have detrimental effects.