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This guidance information is provided by the MDA to assist chlorpyrifos applicators in interpreting application setback requirements found on the label of chlorpyrifos products. The MDA will be inspecting and enforcing the use requirements for chlorpyrifos products based on labeling and these interpretations. It should be noted, however, that the final determinations for MDA enforcement actions are made on a site and case specific basis. This information is not a substitute for the product label. Always carefully read, understand, and follow the product label.

Chlorpyrifos Product Label Language

The following language exists on chlorpyrifos product labels on spray drift management. Requirements are identified by the use of mandatory terms (e.g., must, will, do not) within a sentence.  

SPRAY DRIFT MANAGEMENT

"Do not allow spray to drift from the application site and contact people, structures people occupy at any time and the associated property, parks and recreation areas, nontarget areas, aquatic and wetland areas, woodlands, pastures, rangelands, or animals.
Avoid spraying drift at the application site is the responsibility of the applicator. The interaction of many equipment and weather-related factors determine the potential for spray drift. The applicator is responsible for considering all of these factors when making decisions to apply this product.
Observe the following precautions when spraying this product adjacent to permanent bodies of water such as rivers, natural ponds, lakes, streams, reservoirs, marshes, estuaries and commercial fish ponds. The following setbacks or buffer zones must be utilized for applications around the above listed aquatic areas with the following application equipment."

Application Method Required Setback (Buffer Zone) (feet)
Gound boom 25
Chemigation 25
Orchard airblast 50
Aerial (fixed wing or helicopter) 150


MDA's Interpretation

Interpretation of water body terms

The MDA interprets "rivers and streams" to include natural surface water channels which have flowing water throughout the year (perennial).

Ditches may require application-based setbacks if these surface water channels have flowing water throughout the year (perennial) or at the time of application. Determinations are made on a case by case and site-specific basis. The MDA recommends keeping setbacks from all ditches as a best practice.

The MDA interprets "natural ponds, commercial fish ponds, lakes, and reservoirs" to exclude farm ponds. A farm pond is water impoundment made by constructing a dam or an embankment or by excavating a pit or dugout.

Any open water body that contains water year-round requires chlorpyrifos ground and aerial application label setbacks. This includes all marshes and wetlands that have open water throughout the year.

Where to measure setback distances

Setback distances of 25 feet for ground application, 50 feet for orchard airblast application, and 150 feet for aerial application are measured from the water body's edge at the time of application.