Common Problems Affecting Stormwater Pond Function: Blocked Inlet and Outlet Structures

Inlet and outlet structures of stormwater detention ponds need to be clear to prevent flooding in your neighborhood.

What are Inlet and Outlet Structures?

The inlet and outlet structures of your stormwater detention pond are the most crucial component in maintaining the water level of your pond to prevent flooding in your neighborhood. The inlet structure is where the pipe that collects stormwater run-off from impermeable surfaces such as roads, roofs, and sidewalks empties into the detention pond. The water gradually releases to local waterways through outlet structures.

Sometimes inlet and outlet structures fill with trash, sediment, or overgrown vegetation, blocking water flow and making the area around a detention pond more susceptible to flooding. Keep these structures clear to allow detention ponds to effectively manage stormwater.

What Causes Blocked Structures?

1. Trash and Debris

Detention basin outlet surrounded by trash and debris

During storms, stormwater run-off can carry trash and debris, like leaves and branches, into a stormwater pond. Over time, trash and debris accumulate and block inlet and outlet structures.

It is crucial to continuously remove any trash that collects in your structures to ensure proper water flow and prevent trash from entering local waterways. Trash in detention ponds and waterways impacts water quality, can be harmful to aquatic life, and makes our local waterways look bad.  

2. Sediment

Loose sediment from eroded shorelines and run-off can gather in the inlet and outlet structures, causing a blockage.

If you notice shoreline erosion occurring along your stormwater pond, steps should be taken to prevent further erosion and repair the shoreline.

3. Vegetation

Detention pond outlet blocked by plants

Sometimes vegetation can become overgrown around your inlet and outlet structures. Dense vegetation can inhibit the flow of stormwater to and from a detention pond.

Remove or trim the vegetation around inlet and outlet pipes to avoid blockage.

Other Problems with Detention Pond Structures

Apart from blockage to inlet and outlet structures, there can be other problems associated with the structures, such as cracked or eroded pipes and detached grates. If the structures are damaged, it is best to call an engineer to inspect the inlet and outlet structures.

Grates stop trash and debris from flowing into detention basins and local waterways. Professional assistance may be needed to get a missing grate replaced.

Grate detached from pond inlet structure
A grate completely detached from an inlet structure.

A well-functioning detention basin contributes to optimal stormwater management.

A detention basin, with clear inlet and outlet structures, can be a key feature of effective stormwater management for your community. Since detention pond structures can easily be blocked by trash, sediment, and vegetation, regular maintenance is required. In addition to monthly inspections, inlet and outlet structures should be inspected for blockage after storms to ensure proper flow of stormwater and function of the

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