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White Creek Dredging Project



DNREC is in the bidding phase of a project to dredge White Creek and part of the Assawoman Canal. Both are important navigation channels in the Inland Bays.

White Creek is northwest of Bethany Beach. It flows from the south to the north into Indian River Bay. It serves numerous marinas and boat ramps and connects Assawoman Canal to the bay.

The White Creek navigation channel was last dredged as part of a phased program from 1997 through 2001. The Assawoman Canal was most recently dredged from 2010 to 2015.

Since then, navigability within both channels has decreased due to sedimentation and shoaling.

Project Overview

DNREC’s data-based method to prioritize dredging projects identified White Creek as a top priority. This method includes surveys of residents and users of the waterway. And it considers analysis of channel depth, boater safety and environmental considerations.

A map showing the extent of planned dredging in white creek and the Assawoman Canal
Project Overview Map (PDF)

The project will improve navigability in White Creek and a portion of Assawoman Canal. It will restore an area of highly degraded coastal salt marsh using dredged material. It will help coastal wetlands adapt to sea level rise and other environmental stressors.

The project will remove approximately 55- to 70-thousand cubic yards of shoaled sediments. This will bring the White Creek navigation channel and Assawoman Canal to previous dredge design depths.

DNREC will make beneficial use of the dredged material to restore wetlands in the Muddy Neck Marsh Complex, which is close to the dredging area. This will restore historically degraded wetlands. And it will improve the resilience of the marsh in future coastal storms.

The project will use thin layer placement of dredged materials. This minimizes marsh disturbance and restores the marsh through natural recolonization of vegetation.

DNREC engaged engineering services from Anchor QEA + Woods Hole Group Joint Venture to design the dredge project and oversee its construction.

Project Details

Dredging in White Creek will extend from the mouth of the creek, at Indian River Bay, to where the main channel splits into two prongs near Betts Avenue, in Ocean View. Dredging in the Western Prong will end at Old Mill Road. Dredging in the Eastern Prong will end at the limits of dredge vessel access, near Columbia Avenue.

Dredging in the Assawoman Canal will be between its confluence with White Creek and the Central Avenue bridge.

The White Creek channel will be restored to a depth of 4 feet below mean lower low water (MLLW).  The northern Assawoman Canal will be restored to a depth of 3 feet below MLLW.

Proposed Dredging Area and Volumes

Length
(Linear Feet)
Width
(Linear Feet)
Depth
(MLLW)
Cubic Yards
Dredged
White Creek – Main Channel 11,700 60 -4 29,000
White Creek – Eastern Prong 2,600 35 -4 17,000
White Creek – Western Prong 3,700 35 -4 22,000
Assawoman Canal 2,400 35 -3 2,000
Total 70,000
Note: The depths do not include an allowed “overdredge” of up to one foot. The quantity totals do.

The project will provide multiple benefits, including:

  • Return of navigable depths to recreational boating channels
  • Restoration of severely degraded coastal wetlands in one of Delaware’s premier parks and ecological habitats
  • Improving overall coastal resiliency to part of Delaware’s widely popular inland bay system

Marsh Restoration

The Muddy Neck Marsh Complex is part of the Assawoman Wildlife Area. It is an expansive coastal salt marsh system located west of the southern end of Assawoman Canal. It stretches up to a half mile from the adjacent upland shoreline.

Beneficial Use Cells in the Muddy Neck Marsh Complex

The site is a fragmented tidal wetland complex with several open water pool areas. Plant life in the area includes smooth cordgrass, salt hay cordgrass, spike grass, common reed, glassworts, sea lavender, marsh elder, groundsel bush, salt marsh bulrush and switchgrass.

The Assawoman Wildlife Area supports a variety of fish species, including Atlantic silverside, mummichog, spot, striped killifish, summer flounder and sheepshead minnow.

Restoration of the Muddy Neck Marsh Complex will provide improved habitat value to one of Delaware’s critical natural areas. This area has been subject to ongoing threats of climate change, sea level rise and marsh platform loss.

The Muddy Neck Marsh Complex has experienced widespread ponding and fragmentation over the last 60 to 70 years. Between 2007 and 2017 alone, approximately 11 acres within the Complex changed from vegetated area to open pond. Of the122 acres proposed for marsh restoration, about 70 acres are unvegetated.

Dredged Material Quantities per Cell

Area
(Acres)
Max. Volume
(Cubic Yards)
Avg. Placement
Thickness (Feet)
Cell 1 16.1 13,200 0.5
Cell 2 53.4 85,000 1.0
Cell 3 53.5 50,000 0.6

The project will place restoration material on the marsh using thin layer pressure spray nozzles. Materials will be spread over three areas (Beneficial Use Cells) in thicknesses ranging from a half foot to one foot.

The dredged material will be mostly mud (silt and clay) and some sand. This material is not suitable to place on local beaches (as in the 2020 Masseys Ditch Dredging Project). But this material is ideal for restoring degraded local marshes.

Restoring degraded marshes using dredged material is a common practice nationwide. It and has been done in Delaware. In 2013, DNREC’s Shoreline and Waterway Management Section and Wetlands Monitoring and Assessment Program joined to for a successful marsh restoration at the Piney Point Tract of Assawoman Wildlife Area. That project used a thin layer of material dredged from Pepper Creek.

Numerous projects in southern New Jersey have used dredged material to restore marshes.

Public Information Sessions

On July 28, 2021, DNREC hosted a virtual public information session, attended by approximately 125 people, to share information and solicit questions and feedback about the project.

The public information session included a presentation on the project and has led to development of a set of questions and answers about the project.

second public project information session was held on Jan. 19, 2022.

Project Timeline

Typical Dredge Project Steps
– Pre-Planning/Prioritization
– Planning, Engineering, Design
– Permit Acquisition
– Procurement/Bid
– Construction
– Monitoring

Currently, this project is in the procurement/bid phase.

Contractor bid advertisement, a pre-bid meeting, and bid opening are expected September through October 2022.

If a contract is executed in October, dredging can begin as early as November and should be complete in spring 2023.

The project area will be monitored by DNREC through 2028.

For more information, please contact Joanna French at 302-739-9921.




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