Potential permits required: CWA 404, Threatened & Endangered Species, NHPA, Floodplain
The transport of sand, rock and other sediment is part of the natural cycle of flooding. However, in some cases large amounts of sediment left behind can have negative impacts on properties and the stream system. Removing excess sediment can provide benefits such as:
• Increase conveyance
• Provides ecological benefits
• Increase aesthetics
Sediment is regularly and continually deposited by streams. Large flood events can deposit large amounts all at once.
Removal of sediment is a simple process but understanding how much sediment to remove is an important aspect that can have negative impacts if not done correctly.
If too much sediment is removed in the floodplain, the stream might have the potential to erode the entire bank and move to a new location that damages or threatens property. Removing too much sediment can also confine the stream to a channel where it is not connected to its floodplain. This can cause increased velocities, which cause erosion and damage to nearby properties.
The actual process of removing the sediment can also be a cause for concern. River constructors need to apply for the proper permits and be very careful to not release the sediment into the stream. They also need to be careful to avoid negative impacts to wetlands and wildlife.
Early conversations with outside resources about sediment removal should discuss what the appropriate amount of sediment to remove is and why.
The outside help should be able to explain what the effects of the sediment removal will be, as well as what the final condition will look like. It is also important to recognize that the sediment might not actually have to be removed from your property. Rather, it could be placed in a more advantageous location, such as providing an additional terrace within the floodplain. This terrace could then be planted with willow stakes and other riparian plantings.