Below is a video showing a couple retention ponds for storm water control.
Not too bad an idea. What happens as we expand stores, shopping malls and business parks is we create an area that sheds water like running off a ducks back. There is no chance the storm water can penetrate the earth as it runs along the pavement. So in the parking lots and road ways there are drains that capture the rain water and thru a network of piping, funnels the rain water to the retention pond where it will do one of two things.
One, if it’s a small storm the water will sit there until it evaporates to do it all over again
Two, if the storm continues dropping rain the retention pond will fill until it reaches the trickle tube, down pipe or over flow pipe, which ever you want to call it. Once it reaches the top of the pipe the storm water will be metered out due to the size of pipe and the flow capacity of the pipe.
However you look at it, these ponds have the same three elements a farm pond has. Water supply for the pond, a basin or bowl to retain the water and an exit for the excess of water. The bad part would be the water quality from the parking lots. Who knows what leaks from the cars and trucks these days and what is dropped on the ground. Not a good environment for fish to live in.
In the video the first storm water pond is just starting to fill up. The second is over full and running over the dam. This situation would be extremely scary if it was your own pond. When building a spillway be sure it is large enough to handle the unexpected storms and winter snow melts. Having water running over the dam could lead to erosion of the dam and once started will continue to erode as the pond empties. Your fish will be gone along with the dam material flowing down stream.
Here’s the video take a look.
PS. Be sure to grab your free guide to Ponds at Building a Farm Pond.
Have a GREAT day and take care!