Permits are being required in some situations for application of copper sulfate to water bodies. Copper sulfate is toxic to aquatic invertebrates, such as crab, shrimp and oysters. Copper sulfate and similar fungicides have been poisonous to sheep and chickens on farms at normal application rates. The lethal concentration fifty, or LC50, is that concentration of a chemical in air or water that kills half of the experimental animals exposed to it for a set time period. Copper is considered to be among the more mobile of the heavy metals in surface environments.
Copper is bound, or adsorbed, to organic materials, and to clay and mineral surfaces.
The degree of copper adsorption to soils depends on the level of acidity or alkalinity of the soil. The leaching potential of this material is low in all but sandy soils. When applied to irrigation water, copper sulfate does not accumulate in the surrounding soils. Copper compounds, or precipitates, also settle out of solution, in a process called precipitation. This occurs less often than adsorption.