California has some unique needs in that the state suffers from a drought, but sometimes there are also pouring rains that result in flooding and mudslides. The situation is a complex one within the state—and that’s the reason why there are nine different water boards managing the state’s water supply! Detention and retention ponds are useful for flood control systems, though it’s important to note that there is a difference between these two types of ponds. Detention ponds are designed to temporarily hold water. These are used to capture runoff and divert it, then allow it to drain into the environment or into another part of the flood control system in a controlled manner. Retention ponds are designed for long term water storage.
How can these types of ponds help when California undergoes floods? In cities, paved surfaces can be problematic when rain puddles or even causes flash floods—bad enough that it can lead to traffic accidents or even closed roads. Pavement is not completely impermeable, but water drains through it slowly. Retention and detention ponds are useful to contain this type of water. Meantime, in rural areas, mudslides are a risk in addition to flooding. Many areas in Northern California feature slopes and rugged cliffs prone to collapse unless they’ve been properly stabilized and maintained with an erosion control system. Here, retention and detention ponds are useful not only to capture excess stormwater, but also as fishing or recreational ponds, too, since runoff water in these areas usually doesn’t have a high chemical concentration.
