Grassed Waterways

What is a grassed waterway?

A grassed waterway is a shaped or graded channel planted with low-growing grass or other herbaceous plants that carries stormwater runoff at nonerosive velocity to a stable outlet.

Do you notice any of these issues on the farm?

• Gully erosion
• Runoff from terraces or diversions
• Poor water quality

Grassed waterways have many benefits

• Prevent soil erosion
• Convey runoff from terraces and diversions
• Control stormwater flow
• Increase rain infiltration
• Improve water quality
• Provide habitat for beneficial insects

Other practices are associated with grassed waterways

Grassed waterways are often part of a comprehensive system involving several conservation practices. Some commonly associated practices include:

• Terraces
• Diversions
• Residue management
• Conservation tillage
• Crop rotation
• Contour farming
• Grade stabilization
• Critical area planting

Many design choices are possible

Grassed waterways may look simply broad and shallow, but a variety of factors must be carefully considered in their design. Grassed waterways may have different widths, depths, and vegetation depending on the size of the drainage area, anticipated stormwater amount, surrounding erosion control, and whether the waterway will be built with wildlife habitat in mind. Assistance with design, obtaining permits, and construction is available (see links at the end of this fact sheet for more information).

What maintenance is required?

Grassed waterways require occasional maintenance. The frequency of mowing required for the grassed waterway will depend on its design factors, particularly the type of vegetation selected. Weeds and pests from the waterway may need to be controlled and bare areas reseeded. Inspections should be conducted on a seasonal basis and after major storm and runoff events. If damage such as gulley formation or major sediment accumulation has occurred, the practice designer should be contacted to develop a plan to fix the issue.

Interested in having a grassed waterway?

Grassed waterways are eligible for funding through several conservation programs administered by the State Conservation Commission (SCC) and the Natural Resources Conservation Service (NRCS). Additionally, several local funding sources may be available through organizations such as County Conservation Districts or local nongovernmental organizations. To find design charts for small grassed waterways (for drainage areas of 30 acres or less) from the NRCS, enter "Design charts for small grassed waterways" into any preferred search engine.

For more information, reach out to staff at the Center for Agricultural Conservation Assistance Training (CACAT), NRCS, or your local conservation district office.

Natural Resource Conservation Service (NRCS) Practice Code: 412

Prepared by Chris Canfield and Erin Trouba, Center for Agricultural Conservation Assistance Training, and Sarah Henderson, Department of Ecosystem Science and Management, Cardinale Lab, Penn State.

Photos of grassed waterways

Gulley erosion forming from stormwater runoff. Photo credit: Chester County Conservation District

Grassed waterway immediately after construction. Photo credit: Chester County Conservation District

Grassed waterway in a sunflower field. Photo credit: Kristen Koch, Penn State Ag and Environment Center (AEC)

Established grassed waterway in a corn field. Photo credit: Mikaela Condran, Penn State Ag and Environment Center (AEC)

Grassed waterway among cover crops. Photo credit: Erin Trouba, CACAT

Stabilized area for grassed waterway under construction. Photo credit: Columbia County Conservation District