Abstract In the northeastern United States, we have been removing dams for almost as long as we have been building them, yet many communities involved in current decisions to repair, replace, or remove a dam are not aware of this. This paper highlights some of the stories that have been recorded regarding the history of decision points for dams, including the colorful history of the Billerica Dam in Massachusetts, which has been removed and rebuilt numerous times and is now under consideration for removal for at least the sixth time in its 300 yr history. By understanding that dam removal is just one of the potential dam safety decisions that needs to be analyzed over the life cycle of a dam, and that dams are man-made structures with finite life spans, we can deconstruct the notion of dam removal as a radical concept. Dam removal is just one of many dam safety options that may be discussed over the course of a dam’s history. It is most commonly implemented when a dam no longer serves any economic purpose that justifies the expense of maintaining the dam structure. In the past, dams have been removed for many of the same reasons that we remove dams today; however, the procedures currently required to remove a dam are far more complex and highly regulated. This has led to increased documentation of dam removal efforts and now allows us to compare and categorize dam removal projects, such that the lessons learned from these projects can be incorporated into a more informed decision-making process in the future.

Abstract Paraglacial coastal systems are formed on or proximal to formerly ice-covered terrain from sediments with direct or indirect glacial origin. This review addresses the roles of tectonic controls, glacial advances and retreats, sea-level changes, and coastal processes in sediment production, delivery and redistribution along the paraglacial Gulf of Maine coast (USA and Canada). Coastal accumulation forms are compositionally heterogeneous and found primarily at the seaward edge of the Gulf's largest estuaries; their existence is directly attributable to the availability of glacial sediments derived from erosion of weathered plutons within coastal river basins. Multiple post-glacial sea-level fluctuations drove the redistribution of these sediments across the modern lowland and inner shelf. Central to the formation of barrier systems was the paraglacial sand maximum, a time-transgressive phase of relative sea-level fall and enhanced fluvial sand export c. 2000–4000 years following deglaciation. Vast quantities of sand and gravel were reworked landward during the subsequent transgression and combined with additional riverine sediments to form the modern barrier systems. Today, reduced fluvial sediment loads, anthropogenic modifications of barrier and river systems, and sea-level rise have combined to exacerbate long-term coastal erosion and may eventually force these barriers toward a state of rapid landward migration.