The Penobscot River system plays an important role in shaping the historical and present fabric of Maine. Sediments in the Penobscot River and Estuary are contaminated with mercury as a result of historical releases from a chlor-alkali plant in Orrington, Maine (often referred to as the HoltraChem Plant).
By order of the United States District Court for the District of Maine, a team of engineers and scientists are evaluating how best to reduce the levels of mercury in the Penobscot River system to reduce threats to human health and the environment. This evaluation is called the Phase III Engineering Study.
This website provides background information on the Penobscot River system, how it became contaminated with mercury, and the studies that have occurred and are ongoing.