The drainage ponds become overloaded with nutrients. Most of this nutrient laden water flows through drainage pipes and ends up in the Gulf Of Mexico, where it contributes to algal blooms like Red Tide.
However after a really heavy rain, the banks of the retention pond overflows into the Greenway that is adjacent. Three years ago, that Greenway was a barren patch of sand. Now it is a blooming garden nourished by the overflow from the drainage pond. Mother nature always seeks a balance, here is has turned pollution into a garden.