Retention Pond

This is a planned area of standing water, positioned to receive inflow after a rainfall. It holds the water until it can drain somewhere else.

A retention pond serves two major purposes:

  1. Flood Control. During severe rainfall, there is a risk of the storm sewer system getting overwhelmed. Retention ponds hold water and drain it into the rest of the system at a controlled rate. (Retention ponds are sometimes called “detention ponds” for this reason.)

  2. Water Filtration. When rainwater runs across the ground, it picks up garbage, chemicals, fertilizer, etc. When water stands for an extended period, that sediment falls to the bottom. Therefore, what drains out of a retention pond is much cleaner than what drained into it.

Open Questions

Can you ever build on a retention pond? It exists because either (1) someone designed the drainage to go to that area, or (2) that’s just the way the area naturally drains. If you wanted to drain a retention pond and pill it in, my gut tells me you’d have to just put the drainage somewhere else. My feel is that these ponds are kind of immovable?

Why I Looked It Up

I’ve been asked to join the Property Board at my church. When someone heard this, they took me out back and explained how new parking in a specific location was going to overwhelm the retention pond in the back of the church. I knew there was a pond back there, but I never knew it was intentional nor that it served a specific purpose.

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