Prior to the urbanization of Tampa, a natural balance occurred in the amount of water and nutrients which were delivered to the Bay through stormwater runoff. As the City has grown, this balance has been shifted with an increase in runoff from impervious surfaces such as rooftops and streets--with a greater concentration of human-derived pollutants. Pollutants picked up in the stormwater in the urban area can have significant impacts on the water quality of surface waters such as the Hillsborough River and Tampa Bay. Typically, there is little, if any, stormwater treatment before stormwater flows to a surface water.
| Pollutant | Water Quality Concern |
| Nutrients (such as Nitrogen and Phosphorous) | Promotes weed growth and limits oxygen in the water |
| Sediment | Inhibits sunlight |
| Oil and Grease | Harmful to aquatic systems |
| Toxic metals | Toxic to fish, shellfish and other mammals |
| Bacteria | Human health concerns |
| Trash and debris | Reduced recreation and navigation |
