Grassed Waterways

Hold soil in place and control water flow with grassed waterways.

Grass Roots Effort

As water flows down slopes or hills, it pools in natural dips and depressions in the land. This flow of water can gradually erode the land and form rills or gullies. Your fields are especially at risk if these depressions don’t have enough vegetation growing to hold soil in place.

Grassed waterways are natural or constructed channels of grass or other perennial vegetation in the dips and depressions of your fields. Waterways are graded to slow the flow of surface water to a non-erosive speed.

In other words, when water from a heavy rain washes down your field’s slopes into a valley, a grassed waterway helps control the water flow and directs it toward a stable outlet. By slowing the flow of water, grassed waterways help prevent gully erosion. The plant roots growing in these waterways help hold soil in place and work as a filter to cleanse water of chemicals and nutrients.

Before Waterway Cleanup

After Waterway Cleanup

See an aerial view of Iowa’s grassed waterways from Iowa Farm Bureau

75%

Reduced phosphorus and soil loss by 60-75%

48

Provides habitat for at least 48 bird species

How It’s Done

Grassed waterways are most effective when placed in valleys between hills and other low-lying areas where water collects as it runs off a field’s slope. Grassed waterways may also be used to collect runoff from terraces.

A waterway is typically six inches or more deep. Experts encourage establishing waterways as wide as possible, from 50 to 100 feet. Waterways should not be used as a primary travel lane, but they can give field access for crop scouting and soil sampling.

In Iowa, brome-alfalfa mixes are recommended for grassed waterways because of their ability to repair themselves if they are damaged in a heavy storm. Waterways are usually low maintenance. You’ll have to periodically mow and kill noxious weeds to make them last.

Cost-Share Options

The cost of constructing a grassed waterway depends on the area draining to the waterway, the slope of your land, and the length of the waterway. If only seeding is needed, installation is estimated at around $30–$40 per acre. If you’re looking to construct a waterway from scratch, it could cost around $2,000 per acre. Maintenance costs involve mowing and average $20 per acre annually.State, federal, and private financial assistance programs can help you implement grassed waterways: