Legacy Sediment, Riparian Corridors, and Total Maximum Daily Loads

The Chesapeake Bay Total Maximum Daily Load (TMDL) requires that local jurisdictions reduce sediment and nutrient loads to Chesapeake Bay tributaries. Considerable attention has been devoted to the concept that “legacy” sediment deposits generated by both historical landscape changes and mill dams represent a significant but under-addressed source of sediment and nutrient pollution in the Chesapeake Bay watershed.  Accordingly, it has been proposed that valley dredging should be implemented across broad extents to mechanically remove the “legacy” sediment and nutrient sources. However, there are alternative points of view based on research from the mid-Atlantic region about the relative importance of legacy sediment and historic mill dams as potential sediment sources to the Chesapeake Bay. Fundamental questions remain which may influence whether proposed strategies are effective in reducing loads to the Bay. The Chesapeake Bay Commission requested this STAC workshop be convened to review the scientific evidence comparing alternative strategies for meeting watershed-scale TMDL requirements for sediment and associated nutrients, and assist policymakers in understanding how “legacy” sediment and its remediation fit within a suite of management activities. A report of the proceedings will inform the states as they begin early consideration of their Phase III WIPs in 2017.

This workshop will be structured around expert panel discussions addressing three main themes

A- State of the science, sources of legacy sediment

B- Mitigation and effectiveness of current practices

C- Policy, management, and decision-making