Filter Strip

 

A strip of grass, trees or shrubs that filters runoff and removes sediment, fertilizer, and pesticides before they reach water bodies or water sources including wells.

How it works

Strips of grass, trees and/or shrubs slow water flow and cause contaminants like sediment, pesticides, and fertilizers to collect in vegetation. Collected nutrients are used by the vegetation, rather than entering water supplies. Filtered water then enters water bodies.
How it helps
Grass, trees and shrubs provide cover for small birds and animals.
Ground cover reduces soil erosion.
The vegetative strip moves rowcrop operations farther from a stream.
Vegetation prevents contaminants from entering water bodies, protecting water quality.

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 around a sinkhole, to control runoff from a feedlot or to filter runoff from cropland?

Tech notes

Filter strips are most effective on slopes of 5% or less.
Filter strips for cropland must be at least 15 feet wide.
Steeper slopes require wider strips. *

% Slope Minimum width

0-10 15 feet
10-20 20 feet
20-30 25 feet

A minimum 50 foot width is required for filter strips on forest land.
Do not use a filter strip 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 if filter strips are dry and firm.
Close mowing will reduce filter strip efficiency.

Maintenance

Repair rills and small channels that may have developed.
Control grazing if livestock have access to filter strips.

* Criteria may need to be adjusted for local conditions.