Legacy sediment often accumulated behind ubiquitous low-head mill dams and in their slackwater environments, resulting in thick accumulations of fine-grained sediment.” PDEP Legacy Sediment Workgroup (nd) While appropriate for the immediate task of the PDEP to describe historical GW786034 nmr alluvium along rivers in Pennsylvania, this definition contains specific constraints that limit the definition. A more specific ‘technical definition’ was also presented: Legacy Sediment (n.) Sediment that (1) was eroded from upland slopes during several

centuries of intensive land clearing, agriculture, and milling (in the eastern U.S., this occurred from the late 17th to late 19th Centuries); (2) collected along stream corridors and valley bottoms, burying pre-settlement streams, floodplains, wetlands, and dry valleys; and that altered the hydrologic, biologic, aquatic, riparian, and chemical functions of pre-settlement streams and floodplains; (3) accumulated behind ubiquitous low-head mill dams in

slackwater environments, resulting in thick accumulations of TSA HDAC supplier fine-grained sediment, which distinguishes “legacy sediment” from fluvial deposits associated with meandering streams; (4) can also accumulate as coarser grained, more poorly sorted colluvial (not associated with stream transport) deposits, usually at valley margins; (5) can contain varying amounts of total phosphorus and nitrogen, which contribute to nutrient loads in downstream waterways from bank erosion processes…” PDEP Legacy Sediment Workgroup (nd) To interpret this definition assume that, as in dictionaries, each numbered item provides an alternate definition; that is, these can be interpreted as ‘or’ rather than ‘and’ conditions. Thus, the first

point provides a broad category for agriculturally produced post-settlement alluvium. The second describes a set of lowland sites where LS is likely to be deposited, and the fourth definition includes colluvium. Although these definitions may work well for the region and purposes for which they were derived, they largely constrain the scope of LS to sediment produced by agriculture Farnesyltransferase on hill slopes and deposited in lowlands during post-Colonial time in North America. A more general definition of LS is needed for the various applications of the term that are emerging in the scientific literature. The definition should be flexible enough to include sediment produced by a range and mixture of anthropogenic activities that may have resulted in a wide variety of depositional sites, processes, and sedimentary structures and textures. First, the definition of LS should include human activities beyond agricultural clearance; i.e., lumbering, mining, road building, urbanization, and other land-use practices (Fig. 2).