New Review of Sediment Science Informs Choices of Management Actions in the Chesapeake

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Issue: The Chesapeake Bay Program (CBP) is pursuing restoration efforts to improve habitats and associated water quality for fisheries, both in the watershed and estuary. Excess sediment decreases light in tidal waters for submerged aquatic vegetation, harms oysters, carries contaminants, and impairs stream health throughout the watershed. The CBP is implementing management actions and policies that would reduce sediment transport to Chesapeake Bay, and improve local steam conditions. The efforts to manage excess sediment require improved information on sediment sources, transport, fate, impacts, and implications for management. The CBP partnership has invested in sediment science over the past several decades, but the last comprehensive synthesis was done in 2003.

USGS Study: The USGS conducted a synthesis on the state-of-the-art science of sediment dynamics for the Chesapeake Bay watershed to inform restoration efforts. The synthesis reviewed and summarized multiple aspects of sediment. The review found that rates of erosion and sediment delivery are affected by current climate and land management, but today’s environment was shaped by underlying geology, past climate, and historical land use.

Primary Findings:

  • Fine sediment can degrade the health of aquatic life, especially stream macroinvertebrates and fish, and other important living resources in the downstream Chesapeake Bay.
  • Important sources of sediment in the Chesapeake include the Piedmont physiographic region, urban and agriculture land use, and streambank erosion of headwater streams, whereas floodplain trapping is important along larger streams and rivers.
  • Rates of sediment export differ widely across the Chesapeake watershed, with little evidence yet of widespread declines over time.
  • Best management practices (BMPs) on the uplands and in channels are actively being implemented and are expected to lead to decreased sediment loading. However, reworking legacy sediment stored in stream valleys, with potentially long storage times, can delay and complicate the detection BMPs’ effects on sediment loads.

Management Applications:

The improved understanding of sediment sources, storage areas, and transport lag times can help target choices of BMP types and locations to better manage sediment problems — for both local streams and receiving waters. The findings should be useful for several CBP Teams, including:

  • Water-Quality Goal Team who are focused on reducing sediment to the Bay and tidal waters,
  • Stream Health Workgroup, who are assessing stream restoration opportunities
  • Toxic Contaminant Workgroup, who are addressing impacts of contaminants on fisheries
  • Fisheries Fish Habitat Workgroup, who are coordinating fish habitat assessments of fresh and tidal waters.
Sediment Sources graphic

Read the Article:
Noe, G.B., M. Cashman, K. Skalak, A. Gellis, K. Hopkins, D. Moyer, J. Webber, A. Benthem, K. Maloney, J. Brakebill, A. Sekellick, M. Langland, Q. Zhang, G. Shenk, J. Keisman, C. Hupp, and D. Hogan. 2020. Sediment dynamics and implications for management: state of the science from long-term research in the Chesapeake Bay watershed, USA. WIREs Water; 7:e1454. https://doi.org/10.1002/wat2.1454.

See the Presentation:
Noe, G., K. Skalak, M. Cashman, A. Gellis, K. Hopkins, C. Hupp, D. Moyer, J. Brakebill, M. Langland, A. Sekellick, A. Benthem, K. Maloney, Q. Zhang, D. Hogan, G. Shenk, J. Keisman, and J. Webber. 2018. Reviewing sediment sources, transport, delivery, and impacts in the Chesapeake Bay watershed to guide management actions. USGS Presentation, IP-100396. https://doi.org/10.5066/P92JVLSP.

For more information:
Contact Greg Noe at gnoe@usgs.gov

Posted October 15, 2020.

 

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