Grade stabilization structure at the outlet of a grassed waterway: Full-flow block drop spillway made of wood and cabled concrete. Photo courtesy USDA NRCS.
Grade stabilization structure: Earthen embankment holding water. Photo courtesy Whitewater Watershed Project (MN).
Grade stabilization structure: Water flowing through a full-flow chute spillway made of cabled concrete. Photo courtesy USDA NRCS.
Grade stabilization structure: Recently installed full-flow drop spillway made of metal. Photo courtesy USDA NRCS.
An example of gully erosion. Photo courtesy USDA NRCS.
A gully or grade stabilization structure is an embankment or spillway built across a drainageway to prevent soil erosion. Grade stabilization structures are especially important in areas of Minnesota where sediment loading from gully erosion is a major water quality concern.
Gullies tend to advance upslope at overfalls (small, concentrated waterfalls) below which turbulent water undercuts the head of the gully—a process called head-cutting. Grade stabilization structures control the way water falls to lower elevations, preventing gullies from forming or advancing.
There are many types of grade stabilization structures. Some are full-flow, allowing water to flow freely over a spillway. Others look like a pond and are designed to detain water behind an embankment. Grade stabilization structures are also used to stabilize erosion-prone sites where a tributary or tile drainage outlet enters a channel such as a ditch from the side; the grade stabilization structure slows the flow of water from the higher elevation of the tributary or side-inlet (where water is entering) to the lower elevation of the channel.
Back to top
Guidance from USDA's Natural Resources Conservation Service (NRCS)
See contacts for specific programs that fund this practice in the side-by-side payment comparison or contact your local Soil and Water Conservation District