Grassed Waterways


Grassed Waterways are a shaped or graded, perennially vegetated channel designed to carry runoff at a slow speed to a stable outlet or receiving waterway. As water travels down the waterway, the vegetation prevents erosion that would otherwise result from concentrated flows. When used in conjunction with other field practices, grassed waterways can be easily maintained and will require little cleaning and repair. 


Grassed waterways manage storm flows and snowmelt while protecting fields against gullies and soil loss. The vegetation in the waterway slows down and soaks up incoming water, significantly reducing erosion. The result is a drainage structure that maintains its shape and function over time. Grassed waterways decrease soil loss and sedimentation, thus helping to protect water quality and aquatic organism habitat. Grassed waterways are appropriate wherever row crops or perennial forage crops are grown, including on pastures. 


The length, depth, and width of the waterway will depend on a number of factors, including the size, slope, and soil type of the contributing watershed and the soil type and slope of the waterway. Most grassed waterways are sized to accommodate the ten-year storm event (a storm of such a magnitude has a ten percent chance of occurring in any one year). 

A shallow parabolic (or “U”) shape waterway will resist erosion and be easily crossed with tilling and harvesting equipment. Quickly establishing vegetation on a newly shaped waterway is critical, and construction of the waterway should coincide with recommended planting dates for the chosen vegetation types. The waterway should discharge to a receiving channel such as a stream or other waterbody. Farmers can seek advice on what sorts of discharge arrangements are legal and sustainable from their local NRCS office, from VAAFM staff, and from the VT DEC Water Quality Division. 

Exclude livestock from the waterway. Keep all traffic out of the waterway during wet periods. To maintain the  waterway’s capacity, mow it at least once annually and routinely remove debris that might obstruct the movement of water.

Read the VT NRCS Grassed Waterway Practice Standard here.

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