Converting detention ponds to wetlands

I have designed a stormwater detention basin that impacts an existing wetland. The discharge from the designed basin is to another high quality wetland. Presently, there is no pre-treatment measure proposed for the stormwater runoff. Some government agencies (which will remain nameless) want to see some pre-treatment before discharge. Now, the stormwater basin is designed to maintain a permanent shallow pool.

I want to use this to my advantage. I am guessing that there are other measures that would be necessary to classify the basin as a lower quality wetland that provides some pre-treatment. If anyone knows where I can get this kind of information, I would greatly appreciate it.

The Southwest Florida Water Management District (Brooksville, Florida) has some excellent material on this subject. Did you consider making the basin and wetland one composite area and planting aquatic vegetation in the new portion.

Another contributor adds: First it would be helpful to know what substances the agencies are concerned about. E.g. TSS - total suspended solids, nutrients, total phosphorus, soluble phosphorus or toxic chemicals.

Next, I would model the removal capacity of your designed wet detention pond and compute the probable outflow concentration (based on annual loads, morphometry etc.). If the detention pond is adequately designed, it might just remove enough toxicants etc. to reassure the agencies. Otherwise certain treatments are available, but they depend on the chemical to be removed.