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NRCS, NHCP

September 2016

NRCS reviews and periodically updates conservation practice standards. To 

obtain the current version of this standard, contact your Natural Resources 

Conservation Service State office or visit the Field Office Technical Guide.

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Natural Resources Conservation Service

CONSERVATION PRACTICE STANDARD 

FILTER STRIP

Code 393

(Ac)

DEFINITION

A strip or area of herbaceous vegetation that removes contaminants from overland flow.

PURPOSE

• Reduce suspended solids and associated contaminants in runoff and excessive sediment in surface 

waters. 

• Reduce dissolved contaminant loadings in runoff.

• Reduce suspended solids and associated contaminants in irrigation tailwater and excessive 

sediment in surface waters.

CONDITIONS WHERE PRACTICE APPLIES

Filter strips are established where environmentally sensitive areas need to be protected from sediment,

other suspended solids, and dissolved contaminants in runoff.

CRITERIA

General Criteria Applicable to All Purposes

Overland flow entering the filter strip will be uniform sheet flow. 

Concentrated flow will be dispersed before it enters the filter strip.

The maximum gradient along the leading edge of filter strip will not exceed one-half of the up-and-downhill slope percent, immediately upslope from the filter strip, up to a maximum of five percent. 

Filter strips will not be used as a travel lane for equipment or livestock.

Additional Criteria to Reduce Dissolved Contaminants, Suspended Solids and Associated 

Contaminants in Runoff and Excessive Sediment in Surface Waters.

The filter strip will be designed to have a 10-year life span, following the procedure in Agronomy 

Technical Note No. 2, “Using Revised Universal Soil Loss Equation, Version 2 (RUSLE2) for the Design 

and Predicted Effectiveness of Vegetative Filter Strips (FVS) for Sediment,” based on the amount of 

sediment delivery to the upper edge of the filter strip and ratio of filter strip flow length to length of flow 

path from the contributing area. The minimum flow length through the filter strip will be 20 feet for 

suspended solids and associated contaminants in runoff and 30 feet for dissolved contaminants and 

pathogens in runoff.

The filter strip will be located immediately downslope from the source area of contaminants.
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NRCS, NHCP

September 2016

The drainage area immediately above the filter strip will have a slope of one percent or greater.

Vegetation. The filter strip will be established to permanent herbaceous vegetation.

Species selected will be—

• Able to withstand partial burial from sediment deposition.

• Tolerant of herbicides used on the area that contributes runoff to the filter strip. 

• Stiff stemmed and a high stem density near the ground surface. 

• Suited to current site conditions and intended uses.

• Able to achieve adequate density and vigor within an appropriate period to stabilize the site 

sufficiently to permit suited uses with ordinary management activities.

Plant species, rates of seeding (lbs/ac), vegetative planting (plants/ac), minimum quality of planting stock 

(pure live seed [PLS] or stem caliper), and method of establishment shall be specified before application. 

Only viable, high quality seed or planting stock will be used.

Perform site preparation and seeding/planting at a time and in a manner that best ensures survival and 

growth of selected species. Successful establishment parameters, (e.g., minimum percent ground/

canopy cover, percent survival, stand density) will be specified before application.

Schedule planting dates during periods when soil moisture is adequate for germination and 

establishment. Seeding will be timed so that tillage for adjacent crop does not damage the seeded filter 

strip.

Where the purpose is to remove phosphorus, remove (or harvest) the filter strip aboveground biomass at 

least once each year.

The minimum seeding and stem density will be equivalent to the seeding rate for a high quality grass hay 

seeding rate for the climate area or the density of vegetation selected in current water erosion technology 

to determine trapping efficiency, whichever is the higher seeding rate.

Additional Criteria to Reduce Suspended Solids and Associated Contaminants in Irrigation 

Tailwater and Excessive Sediment in Surface Waters.

Filter strip vegetation will be a small grain or other suitable annual plant.

The seeding rate shall be sufficient to ensure that the plant spacing does not exceed 4 inches (about 16–

18 plants per square foot).

Establish filter strips prior to the irrigation season so that the vegetation is mature enough to filter 

sediment from the first irrigation.

CONSIDERATIONS

General Considerations.

Filter strip width (flow length) can be increased as necessary to accommodate harvest and maintenance 

equipment.

Filters strips with the leading edge on the contour will function better than those with a gradient along the 

leading edge.

Seeding rates that establish a higher stem density than the normal density for a high quality grass hay 

crop will be more effective in trapping and treating contaminants.

When needed, invasive plant species may be controlled through mowing, herbicides, and hand weeding.
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September 2016

Consideration for Reducing Suspended Solids and Associated Contaminants in Runoff. 

Increasing the width of the filter strip beyond the minimum required will increase the potential for 

capturing more contaminants in runoff. 

Considerations for Creating, Restoring or Enhancing Herbaceous Habitat for Wildlife and 

Beneficial Insects and Pollinators. Filter strips are often the only break in the monotony of intensivelycropped areas. The wildlife and pollinator benefits of this herbaceous cover can be enhanced by the 

following:

• When appropriate, use native grass species that fulfill the purpose(s) of the practice while also 

providing habitat for priority wildlife.

• Adding herbaceous plant species (including native forbs) to the seeding mix that are beneficial to 

wildlife and pollinators and are compatible for one of the listed purposes. Changing the seeding mix 

should not detract from the purpose for which the filter strip is established.

• Increasing the width beyond the minimum required. The additional area can increase food and cover 

for wildlife and pollinators. 

• Management activities on filter strips (mowing, burning, or light disking), should not be done more 

often than every other year with frequency dependent on geographical location to maintain the 

purpose(s) of the practice.

• Management activities should be completed outside of the primary nesting, fawning, and calving 

seasons. Activities should be timed to allow for regrowth before the growing season ends.

• Organic producers should submit plans and specifications to their certifying agent for approval prior 

to installation, as part of the organic producer’s organic system plan.

Considerations to Maintain or Enhance Watershed Functions and Values. Filter strips may be used 

to enhance connectivity of corridors and noncultivated patches of vegetation within the watershed, 

enhance the aesthetics of a watershed, and be strategically located to reduce runoff, and increase 

infiltration and groundwater recharge throughout the watershed.

Increase Carbon Storage. Increasing the width of the filter strip beyond the minimum required will 

increase potential for carbon sequestration.

PLANS AND SPECIFICATIONS

Specifications for establishment and operation of this practice will be prepared for each field or treatment 

unit. Record the specifications using the implementation requirements document. The specifications will

identify at a minimum the following:

• Practice purpose(s).

• Length, width (width refers to flow length through the filter strip), and slope of the filter strip to 

accomplish the planned purpose(s).

• Plant species selection and seeding/planting/sprigging rates to accomplish the planned purpose.

• Planting dates and planting method(s).

• Specific care and handling requirements of the seed or plant material to ensure that planted 

materials have an acceptable rate of survival.

• A statement that only viable, high quality, and adapted seed will be used.

• Site preparation instructions sufficient to establish and grow selected species.

OPERATION AND MAINTENANCE

For the purposes of filtering contaminants and nutrients (phosphorus), permanent filter strip vegetative 

plantings will be harvested and removed as appropriate to encourage dense growth, maintain an upright 

growth habit and remove nutrients and other contaminants that are contained in the plant tissue.

Control undesired weed species, especially State-listed noxious weeds.
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If Conservation Practice Standard (CPS) Prescribed Burning (Code 338) is used to manage and maintain 

the filter strip, an approved burn plan must be developed.

Inspect the filter strip after storm events and repair any gullies that have formed, remove unevenly 

deposited sediment accumulation that will disrupt sheet flow, reseed disturbed areas and take other 

measures to prevent concentrated flow through the filter strip.

Apply supplemental nutrients as needed to maintain the desired species composition and stand density.

Periodically regrade and reestablish the filter strip area when sediment deposition at the filter strip-field 

interface jeopardizes its function. Reestablish the filter strip vegetation in regraded areas, if needed.

If grazing is used to harvest vegetation from the filter strip, the grazing plan must ensure that the integrity 

and function of the filter strip is not adversely affected.

REFERENCES

Dillaha, T.A., J.H. Sherrard, and D. Lee. 1986. Long-Term Effectiveness and Maintenance of Vegetative 

Filter Strips. VPI-VWRRC Bulletin 153.

Dillaha, T.A., and J.C. Hayes. 1991. A Procedure for the Design of Vegetative Filter Strips: Final Report 

Prepared for U.S. Soil Conservation Service.

Foster, G.R. Revised Universal Soil Loss Equation, Version 2 (RUSLE2) Science Documentation (In 

Draft). USDA-ARS, Washington, DC. 2005.

Renard, K.G., G.R. Foster, G.A. Weesies, D.K. McCool, and D.C. Yoder, coordinators. 1997. Predicting 

Soil Erosion by Water: A Guide to Conservation Planning with the Revised Universal Soil Loss Equation 

(RUSLE). U.S. Department of Agriculture. Agriculture Handbook 703.

Revised Universal Soil Loss Equation Version 2 (RUSLE2) Web site (checked May 2007): 

http://fargo.nserl.purdue.edu/rusle2_dataweb/RUSLE2_Index.htm.

M.G. Dosskey, M.J. Helmers, and D.E. Eisenhauer 2008. A Design Aid for Determining Width of Filter

Strips. Journal of Soil and Water Conservation. July/Aug 2008—vol. 63, no. 4.