Dissolved and particulate forms of copper are common trace contaminants in storm runoff and wastewater. In the dissolved state, copper appears in various forms, ranging from the cupric ion to numerous organic-inorganic complexes.  The ionic form of copper is toxic at very low concentrations, while complexed copper is basically nontoxic.  Regulatory agencies have long known about this "Jekyll and Hyde" behavior, but the standard permitting approach has been to assume that all dissolved copper is present in the most toxic form, which is rarely accurate because the ionic form is highly reactive, readily forming nontoxic complexes.

The Albemarle-Pamlico estuary of North Carolina is the second largest and one of the most productive estuarine systems in the country. Over the past two decades, excess nutrients entering the estuary from the Tar-Palmetto River have caused algal levels to increase. These increased levels can lead to fish kills, odors, and habitat loss and can generally diminish water quality.  The system has also suffered significant losses in wetlands, submerged aquatic vegetation, and spawning areas due to real estate development.