Diquat use in a public water supply watershed?

• A. Allowed for use in all public water supply watersheds with minimal restrictions
• B. Allowed for use in some public water supply watersheds with notification
• C. Allowed for use in private water systems only
• D. Not permitted for use in a public water supply watershed

Answer: (D)

Not permitted for use in a public water supply watershed. The situation tests how protecting drinking-water sources governs pesticide use. Diquat is an aquatic herbicide, and applications can lead to residues entering water supplies through drift or runoff. Because public water systems must guard against any contamination, using diquat within areas that feed public water intakes is prohibited by the product label and state regulations. Other contexts outside public water supply watersheds may have allowances or notification requirements, but the watershed providing a public drinking water supply is treated with strict restraint to keep water safe. Always follow the current label and local rules, but in this scenario, protection of the public water supply dictates no use.