Filter Strip

A strip of herbaceous vegetation that filters runoff and removes contaminants before they reach water bodies or water sources, such as wells.

How it works

Strips of herbaceous vegetation slow water flow and cause contaminants like sediment, chemicals and nutrients to collect in vegetation. Collected nutrients and chemicals are used by vegetation before they enter water bodies.

How it helps

• Prevents contaminants from entering water bodies to protect water quality
• Reduces soil erosion
• Provides cover for small birds and animals
• Moves agricultural operations farther from a stream

Planning ahead

• Are adequate soil conservation measures installed above filter strips?
• Are plants adapted to your soil types?
• Have you selected the correct species of vegetation for the control you need? For example, are you establishing the filter strip to control runoff from a feedlot or to filter runoff from cropland?

Technical notes

• Filter strips are most effective on slopes of 5% or less.
• Filter strips should be at least 20 feet wide unless location and design indicate a wider filter strip is needed.
• Do not use filter strips as a roadway.
• Filter strips will be less effective under snow or during frozen conditions.
• Avoid drift when applying herbicides on surrounding cropland.
• Controlled grazing may be allowed on dry, firm filter strips.

Maintenance

• Repair rills and small channels to prevent concentrated flow through the strip.
• Control grazing if livestock have access to filter strips.
• Control undesirable weed species, especially state noxious weeds.
• Inspect the filter strip after storm events. Repair gullies, remove unevenly deposited sediment, and reseed if necessary.
• Periodically regrade when deposition jeopardizes function; re-establish strip if needed.

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Last Modified:  09/10/2007