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Grassed Waterway

Grassed Waterway









Grass established in a shaped drainageway to prevent gullies from forming.

How it works

A natural or constructed drainageway is graded and shaped to form a smooth, concave channel. This area is seeded to suitable vegetation. Runoff water that flows down the drainageway flows across the grass rather than tearing away soil and forming a gully. An outlet is often installed at the base of the drainageway to stabilize the waterway.

How it helps

  • Conveys runoff from terraces, diversions, or other concentrations without causing erosion or flooding
  • Protects drainageways from gully erosion
  • Filters chemicals and nutrients from runoff water
  • Provides cover for small birds and animals

Planning ahead

  • Is major land reshaping needed?
  • Is there a proper outlet for surface runoff at the bottom of the waterway?
  • Are soil conservation measures installed to prevent siltation?
  • Will tile drainage be necessary?

Technical notes

  • A waterway should be deep enough and wide enough to carry peak runoffs.
  • Plant at recommended times and rates; follow site preparation recommendations.
  • Nurse crops, temporary cover or mulching may be needed until permanent cover is established.


  • Maintain the shape and depth of the channel and the stability of the outlet.
  • Lift implements out of the ground and shut off spray equipment when crossing.
  • Do not use waterways as roads.
  • Fertilize as needed.
  • Mow prior to the rainy season to maintain desired vegetation. Consider nesting seasons for native wildlife before mowing.
  • Maintain the width of the area when tilling surrounding fields.
  • Avoid planting end rows along the waterway. This prevents a new gully from forming on the outside edges and allows runoff to reach the waterway.
  • Inspect the waterway and outlet yearly and/or prior to the rainy season.