Cloud seeding has been conducted off and in the central Sierra — including the north fork of the Stanislaus River — since the 1950s. … There have been some groups, including the National Park Service responsible for the 1,169 square miles within Yosemite National Park, seeking to end the practice due to concerns the chemicals used can cause damage to ecological systems. The California Department of Water Resources’ latest published study on “precipitation enhancement resource management” references previous research that notes winter orographic cloud seeding can improve precipitation between 4 and 15 percent. Orographic cloud seeding is where wind blows over a mountain range causing clouds and rain or snow to fall by lifting the air. It is an entirely different process than what is used in areas such as Central Texas.
–Written by Dennis Wyatt, editor of the Manteca Bulletin.