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Tred Avon River and Harris Creek Oyster Reef Restoration

The U.S. Army Corps of Engineers and partners restarted oyster restoration in Harris Creek in January 2015. This effort is part of the Maryland and Virginia statewide oyster restoration program, as laid out by the Corps’ Native Oyster Restoration Master Plan that identifies the most suitable tributaries throughout the Chesapeake Bay for large-scale oyster restoration based on physical and biological conditions. New construction in Harris Creek consists of placing 57 acres of reef in water 6 to 9 feet deep (mean lower low water, MLLW). Similar work in the Tred Avon River is also scheduled to begin this winter, and efforts may occur simultaneously. In the Tred Avon, 24 acres of reef will be placed in water 9 to 20 feet deep (MLLW).

View a map of the proposed restoration sites to construct 1-foot reefs in deep-water segments of the Tred Avon River by clicking here. Work will include constructing 1-foot reefs using rock and mixed-shell materials. Constructed reefs will be made of: 1) rock only, 2) combination of rock and mixed shell, or 3) mixed shell only. The shell comes from processing plants in the mid-Atlantic region and is permitted to be imported and placed in the river. The rock is quarried in Havre de Grace, Md.

Through the interagency partnership, the State has planted more than a billion oysters in the Harris Creek Sanctuary since 2011. Since restoration efforts started, areas with less than one oyster per square meter now have upward of 25 oysters per square meter. The site now contains oyster beds that continue to grow and reproduce. Once fully restored, the Harris Creek sanctuary will work to improve water quality and enhance fish habitat.


Tred Avon River User Input

The Corps appreciates the public input received through both the informal comment period, which closed Oct. 15, 2014, and the public Open House held Nov. 7, 2013, in Oxford, Md. Where applicable, this input has been incorporated into oyster reef construction plans, and will also assist in developing a supplemental environmental assessment for proposed future oyster restoration work in the 6 to 9 feet deep areas of the Tred Avon River.


Harris Creek Environmental Assessment

Previously, National Environmental Policy Act (NEPA) documentation evaluated the impacts of oyster reef restoration at water depths that maintain at least an 8-foot water column above restored reefs, including many proposed sites in Harris Creek. The Corps prepared a supplemental Environmental Assessment evaluating the impacts of expanding oyster restoration and rehabilitation activities into water depths between six and nine feet. This would maintain at least a 5-foot water column above restored reefs within the Harris Creek oyster sanctuary. The supplemental Environmental Assessment determined there would be no significant environmental impact as a result of this proposed action. Comment period closed April 21, 2014. View the Final Environmental Assessment for Harris Creek.


Oyster populations in the Chesapeake Bay have declined dramatically in the last century, largely due to parasitic diseases, overharvesting, declining water quality, and a loss of habitat. Less than one percent of historic oyster populations remains. Oyster restoration is important because oysters provide a number of environmental benefits, including reef habitat that is significant to the Bay ecosystem for animals like blue crabs and fish. Additionally, oysters are filter feeders that improve water quality.

The Native Oyster Restoration Master Plan is the Corps' plan for large-scale, sanctuary-based (through Maryland Department of Natural Resources) oyster restoration throughout the Chesapeake Bay and its tributaries. The master plan examines and evaluates the problems and opportunities related to oyster restoration, and formulates plans for implementing large-scale, Bay-wide restoration.

Project elements include: (1) disease-free spat (oyster seeds) from state-owned hatcheries; (2) creation of new oyster habitat; (3) rehabilitation of existing non-productive oyster habitat; (4) construction of seed bars for production and collection of spat; (5) planting spat on the new and rehabilitated bars; and (6) monitoring of project performance.

The Maryland Department of Natural Resources (MDNR) is the non-federal sponsor for Corps’ oyster restoration activities in Maryland. Additional project partners include the National Oceanic and Atmospheric Administration (NOAA) and the Oyster Recovery Partnership (ORP). NOAA maps available restorable water bottom using sonar in conjunction with various ground‐truthing methods and funds the production and planting of seed oysters. The Corps constructs reef structure where none currently exists. ORP plants oyster spat (baby oysters) grown at the University of Maryland Horn Point Hatchery on restoration sites.

Restoration only takes place in pre-existing sanctuaries, as established by MDNR. Sanctuaries are areas that are closed to harvest; however, oysters within sanctuaries are expected to increase the abundance of adult oysters whose larvae are expected to settle not only within the sanctuary, but also on public shellfish fishery areas in the vicinity of the sanctuaries.

Typically, there are two barges used for constructing the reef: one barge holds the substrate, the other holds a crane with a bucket to move the substrate.  The bucket picks up the substrate from the barge, then, with a sweeping motion, releases it into the water.  GPS locaters are used to make sure the reefs are constructed in the selected sites. Oyster seed, which are technically referred to as spat on shell, are brought from hatcheries and placed or “planted” on the constructed reefs in hopes of restoring the oyster population in these areas.  Once planted, the oyster reefs will be monitored to assess the restoration progress.

The Corps is involved in oyster restoration in two ways. Through an authority under Section 704(b) of the Water Resources Development Act (WRDA) of 1986, as amended, the Corps provides construction assistance for certain oyster restoration projects through its Civil Works program. For work undertaken by others, the Corps evaluates the impact of dredged or fill material into Waters of the United States under Section 404 of the Clean Water Act and Section 10 of the Rivers and Harbors Act, through a permitting process managed by the Corps Regulatory Program.

The Maryland project cooperation agreement was executed in February 1997, with an amendment in July 2002.  Placement locations in Maryland include Kedges Strait, Eastern Bay; and the Chester, Choptank, Magothy, Patuxent, and Severn rivers (and soon to be Tred Avon) - a total of approximately 600 acres of new oyster bars. Some of the oyster bars were left for natural recruitment; others received hatchery-raised spat. The Virginia project cooperation agreement was executed in September 2001, with amendments in July 2004 and June 2007. The Corps' Norfolk and Baltimore districts support activities in Maryland and Virginia, respectively. In Virginia, activities include oyster bar creation in Tangier Sound, Pocomoke Sound, the Great Wicomico River, and the Lynnhaven River - a total of approximately 400 acres of new oyster bars.

Prior to the 2009 restoration activities, the Corps oyster restoration program did not focus on large-scale tributary restoration in Maryland, as it does now.  From 1997 to 2006, the Baltimore District received relatively small funding allocations for a number of small sites, scattered throughout the Maryland portion of the Chesapeake Bay.  An assessment of the sanctuary sites constructed during this period was prepared and can be found in the September 2011 report, 2008 Sanctuary Assessment.

Larval Transport Model

Additional Information

Authorization: Section 704(b) of the Water Resources Development Act of 1986, as amended.

Type of Project: Aquatic Ecosystem Restoration

Contribution to the Chesapeake Bay: Directly contributes to Executive Order 13508 goals to restore clean water, recover habitat, and sustain fish and wildlife.

Project Phase: Construction

Non-Federal Sponsor: Maryland Department of National Resources, Virginia Marine Resources Commission

Congressional Interest:  Senators Mikulski and Cardin (MD), Warner and Kaine (VA); Representatives Harris (MD-01), Sarbanes (MD-03), Hoyer (MD-05), Wittman (VA-01), Rigell (VA-02), and Scott (VA-03).


The FY 2014 Maryland contract was awarded August 2014.  For this contract, mixed shell and a granite-like material will be placed as substrate on 57 acres of shallow water in Harris Creek and 24 acres of deepwater in the Tred Avon River.  The work is anticipated to start fall 2014 and end spring 2015.  Monitoring of the Virginia sites has shown that many of the Great Wicomico and Lynnhaven River sanctuary oyster reefs are exceeding the accepted target for successful oyster restoration. 



Total Estimated Cost (MD+VA)


Federal Cost Estimate


Non-Federal Cost Estimate 


Federal Funds Data  
Allocation thru FY 2013


Allocation for FY 2014


President Budget FY 20152


Allocation for FY 20152


Balance to Complete


1 Estimate based on the current Federal authorization for this program. The long-term master plan has identified a need of $2-6 billion.

2 The President typically sends the budget to Congress in February each year. Upon release, budget amounts for the USACE Civil Works programs and specified projects are posted online at the USACE website in a program budget press book at http://www.usace.army.mil/Missions/CivilWorks/Budget.apsx

3 The final FY 2015 allocation of funds to projects will be available upon enactment of the Energy and Water Appropriations Act or the public release of an approved FY 2015 work plan, given continuing authority for the full year.  The FY 2015 funds will be distributed between Baltimore and Norfolk districts.



FY 2014 Completed Work (Baltimore District): Construction of the 2013 substrate sites, 23.3 acres in Harris Creek, was completed April 2014.  In August 2014, a contract was awarded to Argo Systems, LLC, for substrate construction in Harris Creek and the Tred Avon. Project monitoring continued at all sites.  

FY 2015 Scheduled Work: Construction of the 2014 substrate sites in Harris Creek and Tred Avon. With anticipated FY 2015 Federal funding, design and award construction for additional acreage in the Tred Avon. Continue project monitoring.     

COMPLETION: TBD.  With optimal funding and an increase in WRDA cost authority, oyster restoration activities would continue toward achieving the oyster restoration outcome guided by the implementation strategy associated with the Chesapeake Bay Protection and Restoration Executive Order (E.O. 13508) and the Chesapeake Bay Watershed Agreement to restore native oyster habitat and populations in 10 tributaries by 2025.

Point of Contact

Baltimore District Public Affairs