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Maryland Oyster Restoration

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Tred Avon River and Harris Creek Oyster Reef Restoration Updates

Notice to Mariners: View the Harris Creek Oyster Restoration map that identifies where the Corps and Maryland DNR have placed rock and shell to restore oyster habitat in Harris Creek. In the areas identified, water depths are 1 foot to up to 2 feet shallower than what is currently shown on navigational charts. NOAA is revising the charts to reflect these restoration areas and depths. Please be vigilant when navigating through these areas.         


Overbuilt Reefs: In 2015, the Corps constructed 55 acres across 24 sites of oyster reef in Harris Creek. Ten of these 24 sites had locations in which the contractor overbuilt some of the reefs, which lowered the navigable clearance for vessels. The Corps takes any impediments to navigation seriously, and we completed corrections to these identified locations March 11, 2016. 

The Corps will re-survey the area by or before spring 2016 to ensure accuracy.  The Corps is working on a process to more efficiently conduct post-construction surveys before the spat-on-shell is placed, and we are also looking into tightening quality control methods with our contractor. This will help ensure that restoration is performed as laid out in the tributary plan and contract, will allow for immediate corrective actions to any overbuilt reefs, and will cut down on any potential navigation hurdles in the future.  

Though the Corps has not received any official claims to date for work our contractor constructed within the Harris Creek project boundaries, if we do receive claim information, we will then determine the best path forward for processing the claim.

For more information, mariners and watermen can reach out to Anna Compton, the Corps Maryland Oyster Restoration project manager, at 410-962-4633 or anna.m.compton@usace.army.mil.    

Also, we want to remind mariners to please heed their USCG local notices. 


NEW Survey Results: Preliminary data show oyster restoration in Harris Creek is doing well. Through the interagency partnership, the State of Maryland has planted more than 2 billion oysters in the Harris Creek sanctuary. Fall 2015 Harris Creek Oyster Density survey indicates 100 percent of the 102 acres completed in 2012 exceed healthy restoration standards – exhibiting 15 oysters per square meter. Fifty percent of the sites had more than 50 oysters per square meter (meeting the restoration target). 


Oyster restoration efforts are 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.

Harris Creek restoration work was completed in summer 2015 with the construction of 350 acres. Oyster restoration is planned in the Tred Avon River across 83 acres. Work includes constructing 1-foot reefs using mixed-shell materials and rock. The shell comes from coastal processing plants and is permitted to be imported and placed in the river. The rock is quarried in Havre de Grace, Maryland. View Tred Avon River oyster restoration map.

The Corps and its partners have engaged with the Maryland's Watermen Association to discuss a path forward for working more closely together throughout the restoration process. Following a series of meetings and visits to the restoration sites with the watermen, the interagency team limited the use of rock planned during spring/summer 2015 restoration to three sites in the Tred Avon River. The remaining reef sites planned will be made of mixed shell. This change affects the following sites identified on the Tred Avon map: 39, 40, 43, 44, 60, and 61. These sites had originally been planned to be either 12 inches of rock or 6 inches of rock with a 6-inch mixed shell cap. They will now be constructed completely of mixed shell. This change was made to minimize impacts to trotlining by crabbers in the Tred Avon River. In Harris Creek, the following sites were constructed completely with rock: 43B, 53, 55, and 58. Extensive reef construction using rock had been completed prior to this work in Harris Creek. Restoration plans are subject to funding and the availability of material.

The University of Maryland's Paynter Lab published a report regarding the 2014 monitoring of Cook Point, which is a site used to evaluate how well reefs made of various alternate materials (other than native shell) are performing for oyster restoration. Our interagency partners and we take research and monitoring seriously because we want to ensure our oyster restoration efforts are working. Overall, this study found that reefs made of alternate substrate like rock and mixed shell at the Cook Point Sanctuary are supporting dense, healthy oysters and reef habitat. The report seems to show that rock and rock/shell provide suitable habitat for oyster restoration. It supports that 1 foot is suitable in reef height for restoration efforts. The report also indicates that incorporating shell into the reef improves restoration performance. This report supports the reef design work the Corps has done and will most likely continue to pursue in the future.


U.S. Army Corps of Engineers, Maryland Oyster Restoration Overview

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 U.S. Army Corps of Engineers 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, Severn and Tred Avon rivers - 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.

Oyster Restoration Larval Transport Model

This video shows a model of the movement of oyster larvae in Harris Creek. As you can see, the benefits of restoration extends beyond the sanctuary boundaries and into areas that can be harvested.

Additional Maryland Oyster Restoration 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).

Maryland Oyster Restoration Schedule


FY 2015 Completed Work: Completed the Tred Avon River tributary plan and draft Supplemental Environmental Assessment. Constructed 55 acres of reef in Harris Creek and 16 acres in the Tred Avon River. In Norfolk District, design and construction was completed for rehabilitation of existing reefs in the Great Wicomico using more than 15,000 cubic yards of fossil shell. A decision document amendment was completed, and NEPA is nearly completed for work in the Piankatank River.

FY 2016 Scheduled Work: Previous year carry-in funds in the amount of $3.6 million ($2.65 million in Baltimore District and $1.9 million in Norfolk District) along with the fiscal 2016 allocations based on the president’s budget ($985,000 Baltimore District, $985,000 Norfolk District) are being used to: In Baltimore District, complete reef construction of 8 acres in the Tred Avon River pending direction from Sponsor, finalize the Supplemental Environmental Assessment for the Tred Avon River, plan for design and construction of the next Tred Avon River substrate contract and continue program coordination and monitoring of seeded reefs. In Norfolk District, adaptive management of reefs constructed in the Great Wicomico River, development of a tributary plan for the Lafayette River, completion of Preconstruction Engineering and Design (PED) for the first phase of construction in the Piankatank River and award for construction of approximately 39 acres in the Piankatank River.      

COMPLETION: TBD. Continuing oyster restoration efforts toward achieving 10 restored tributaries by 2025 will require an increase to the authorized program cost limit. As of fiscal 2016, approximately $51 million of the $60 million in program authority has been appropriated. This roughly equates to two more years of construction remaining prior to reaching the program limit. The tributary goals are established by the Chesapeake Bay Protection and Restoration Executive Order (E.O. 13508) as laid out in the May 2010 Strategy for Protecting and Restoring the Chesapeake Bay Watershed that called for restored oyster populations in 20 Chesapeake Bay tributaries by 2025. The 2014 Chesapeake Bay Agreement later adapted this goal to 10 tributaries by 2025.

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