A stormwater pond rarely fails all at once. It fails a little at a time, in places that are easy to overlook from the clubhouse. Most of what follows takes a few minutes to spot and is inexpensive to fix early. Left alone, almost every item ends up in the same place: a special assessment.
The forebay is filling in
The forebay is the shallow settling cell where the storm drain enters. It’s built to catch sediment where a truck can reach it. Once it fills, sediment moves into the main pond instead. A forebay cleanout is a day with an excavator. Dredging the main pond five years later is the most expensive thing that can happen to it.
The pond won’t draw down after a storm, or drains too fast
The riser and its low-flow pipe set how quickly the pond releases water. When the pipe blocks or the trash rack goes missing, the pond stops performing to its approved plan. This is the failure most likely to produce a letter from the county.
Trees and brush on the embankment or spillway
Woody growth on the embankment weakens it, and an overgrown emergency spillway can’t pass an extreme storm safely. While it’s still just vegetation, it’s one of the easiest deficiencies to correct.
Wet spots or sinkholes on the dry side of the embankment
Water travelling along the outside of the outlet barrel can erode an embankment from the inside, where nobody sees it. Caught at an inspection, it’s a repair. Found after a storm, it’s an emergency.
The bank is sliding or undercut
Wave action undercuts the toe of the slope and the safety bench narrows until it’s gone. Shoreline restoration is priced by the linear foot, and the length grows every year you wait.
Loose or buried stone at the outfall
The stone apron at the outlet takes the energy out of water leaving the pond. Once it’s gone, the channel scours and the damage works back toward the embankment.
Green water and a smell in late summer
Often a sign the pond has lost depth to sediment, warmed and run short of oxygen near the bottom. The fix is sometimes aeration rather than a chemical contract, which is why it’s worth diagnosing before treating.
Catch it early, and write it down
The common thread is timing. Each of these is a small deficiency before it’s an expensive repair, and a record of when it was found is what lets a board plan for it instead of reacting to it. Our interactive pond diagram walks through each part of a wet pond, how it fails and what that costs.
If you’d rather have someone else take the walk, a site assessment gives you a written, photo-documented account of all of the above, with the fixes in order of what it costs to wait.