Potomac River. Oyster aquaculture in the Potomac River estuary could result in significant improvements to water quality, according to a new study. All of the nitrogen currently polluting the Potomac River estuary could be removed if 40 percent of its river bed were used for shellfish cultivation, according to the joint study. The researchers determined that a combination of aquaculture and restored oyster reefs may provide even larger overall ecosystem benefits. Oysters, who feed by filtering, can clean an enormous volume of water of algae which can cause poor water quality.