There are a lot of great designers out there offering workable ideas for stormwater treatment and control. Parking lot bioswales (depressed areas to treat and/or control storomwater runoff are a great example of their thinking. This is only one example: With anything, once it's built, it requires maintenance to function properly. The permitted facility shown below is rather new (around a year old) and it's intended function is already significantly impaired. Here' is what sometimes happens: Outlet structure blocked by debris and dead plant material. Landscaping/sod has died and sides are eroded.