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July 14, 2000

ENF 2000-028

TO: County Agricultural Commissioners

SUBJECT: MAGNACIDE H HERBICIDE--LABEL STATEMENTS INTERPRETATION

We received a request for an interpretation of statements on the Magnacide H Herbicide (U.S. EPA Registration No. 10707-9) label. Magnacide H, active ingredient Acrolein, is a common aquatic herbicide used to control algae and weeds in canals and ditches.

Under the label heading, "DIRECTIONS FOR USE," is the statement, "Do not release treated water for 6 days after application into any fish bearing waters or where it will drain into them." This statement is very clear and enforceable. Magnacide H treated water cannot be released from the canal system, or into a field where the drainage water from that field would enter a body of fish bearing water within 6 days of the end of the treatment. In the specific case described in the request for interpretation, water from a flood control district was treated with Magnacide H and eventually drained into a creek; a fish bearing waterway. Unless the flood control district can hold the treated water in its canal system, or on a field for 6 days, the application would be in conflict with the label.

For regulatory purposes, a definition of "treated water," in the case of a canal is the portion of water moving through the canal between the start and end of the Magnacide H treatment. This "slug" of treated water could not be released into fish bearing water for 6 days, according to the Magnacide H label statement. The 6-day clock would start when the Magnacide H stopped flowing into the canal.

There is no other statement on the label allowing for release of the treated water based on apparent weed control or other monitoring activity.

If you have any questions, please contact the Senior Pesticide Use Specialist serving your county.

Sincerely,

original signed by

David Duncan, Acting Chief
Pesticide Enforcement Branch
(916) 445-3871

cc: Mr. Daniel J. Merkley, Agricultural Commissioner Liaison

NS