Of 400 samples representative of water resources in California, 25% were found to contain toxic levels of lithium, capable of adversely affecting the growth of citrus and other crops. Water samples with a high lithium content were usually associated with low magnesium and/or a high sodium percentage. Because of the natural occurrences of toxic levels of lithium in irrigation water, as well as possible contamination from industrial uses of lithium compounds, agencies responsible for maintaining water quality standards should also include analysis for lithium along with their routine sampling.

David L. Shatto, Assistant Public Health Chemist with the State Department of Water Resources Laboratory at Riverside, made available analytical data, maps, etc., which assisted in the preparation of this report.