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Herd of cattle

Manure Application Setback

Manure application setback guidelines for Whatcom are based on scientific studies which recommend specific distances for sediment and nutrient removal based on seasonal precipitation and soil saturation conditions.

Manure Application Setback Distances (in feet)

  1. These are minimum distances and may need to be increased during un-seasonally wet periods. 

  2. A big gun applicator should NEVER be closer than 40 feet at any time of the year due to drift.

  3. Application during November and December is typically not necessary and must be shown to be agronomic before manure is applied.

  4. Any manure application made from November-February must have a winter spreading plan in place. Contact your CD planner to add this  to your DNMP.

  5. These guidelines apply equally to both liquid and solid manures.

Click here for guidance for Application Risk Management.


A distance of 40 feet has been shown to be most effective at preventing runoff of surface nutrients and sediment during spring and fall rain events. We allow that distance to be reduced to 10 feet in the dry summer months when the chance of runoff is slight. The setback distance is increased to 80 feet in the late fall through the winter to be protective against periods of heavy, prolonged rain events, and/or saturated soils. Application during this risky time can readily move surface applied manure from your field if you’re not careful.

If you have any discharge of nutrients you may be put under the penalty of an EPA CAFO permit with a mandatory setback of 100 feet year-round.

When applying manure, remember to follow these setbacks as well as site specific guidance found through the ARM Weather Map. These setbacks will help you avoid applying too close to a waterbody or sensitive area when the risk of runoff is high. Your Nutrient Management Plan requires the implementation of these setbacks.

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