Higbee Beach Wildlife Management Area Tidal Marsh/Upland Restoration Project
LOCATION: Higbee Beach Wildlife Management Area (WMA), Lower Township, Cape May Point
PURPOSE: To restore tidal hydrology and function to Pond Creek
in the WMA and to restore upland areas of the WMA which were degraded by the manufacturing operations from the former Magnesite to create and enhance habitat for migratory birds, fish and various threatened and
endangered (T&E) species.
SUMMARY: The Higbee Beach WMA Restoration Project will result in
over 400 hundred acres of restored and enhanced wetland and upland maritime habitat. These acres fall within the known ranges of resident bird species and will be particularly important to annual spring/fall bird migrations since Cape May is an integral part of the Atlantic Flyway. For example, a large percentage of the entire western Hemisphere’s population of the NJ State-listed Red Knot
has been documented to utilize the Cape May peninsula in the vicinity of the
project area during their annual migrations. The restored wetland project area
will provide foraging and loafing habitat for raptors, such as osprey, peregrine
falcons, merlins, kestrels, cooper hawks, and sharp shinned hawks during their
migratory season as well as increase food, shelter and general habitat for
numerous species of fish, amphibians, reptiles, and mammals.
The New Jersey Division of Fish and Wildlife actively encourages the public to use Higbee WMA lands for a variety of recreational uses including: bird watching, photography, hiking, fishing, and hunting. The project will visually open up Pond Creek tidal and freshwater habitat and provide access for viewing via a bridge crossing over the new tidal channel, berms, and connecting trails that loop around the entire project area. A portion of the Magnesite property will be reserved for a future interpretive/education center that will be used to enhance visitors’ understanding and appreciation of the newly restored habitats and the wildlife drawn to them.
Throughout the design process, ONRR collaborated with various stakeholder agencies and organizations to develop a remarkable habitat restoration project that provides ample viewing opportunities to this globally renowned birding destination. Historic site manipulation cut off Pond Creek Marsh from tidal influence, resulting in degraded habitat dominated by non-native Phragmites australis (Phragmites). To restore full tidal inundation to a majority of the marsh, the restored inlet was established through an iterative process of defining, modeling, and refining the inlet channel design. Branching off this main channel, interior 1st, 2nd, and 3rd order channels were designed to convey full tidal inundation and drainage of the marsh within a daily tide cycle. Additionally, the design aims to enhance habitat diversity by eradicating Phragmites with the inundation of saltwater and through the incorporation of high marsh islands, habitat clusters, mud flats, open water features, and sand-shell islands throughout the Pond Creek marsh.
For managing flood risk from periodic storm surge events and future sea level rise, the project includes a 6,861-foot earthen berm system fitted with flow control structures designed to control tidal inundation of eastern portions of the Higbee WMA along an alignment within the marsh that balances stakeholder objectives for restoring as much salt marsh as possible within, while protecting freshwater habitat and groundwater resources. The top of berm elevation was set is 7.5 feet which was deemed appropriate given the design goal of providing a reasonable level of tidal inundation protection to the upper watershed, considering the landscape context and regional flooding pathways.
To drain stormwater input from the watershed east of the tidal inundation control berm, five water control structures were incorporated into the berm design, including: three 4-foot-diameter corrugated metal pipes with dual check valves; one 4-foot-diameter reinforced concrete pipe with inline check-valve; and one 12-inch-diameter reinforced concrete pipe with inline check-valve and trash rack.
To provide targeted habitat control for migratory birds an 851-foot-long northern berm along a northern finger of the Pond Creek marsh was incorporated. This section of marsh will be restored through excavation and removal of Phragmites and planting of native salt marsh species. Water levels within the northern marsh will be managed by NJDEP during short periods of target bird migration using a water control structure consisting of a 6-foot corrugated metal pipe with flap gates. The structure can be set to allow tidal inundation ponding or drain the area behind the berm to provide tidal marsh, open water, and/or mudflat habitats.
Construction of the earthen berms will require suitable subgrade reinforcements along their alignments through the marsh plain. NJDEP collaborated with New Jersey Department of Transportation (NJDOT) to obtain material from a local Confined Disposal Facility (CDF) as the source of granular fill for the project. This supported NJDOT’s need to create capacity in the CDF for future dredging projects and provided a beneficial use for the dredge material.
Uplands within the project area are predominately covered with non-native species and patches of barren land where compacted, high pH material from the former Harbison Walker Magnesite facility are exposed. The proposed upland habitat consists of a mix of maritime forest and coastal successional/old field habitat. To manage costs, marsh material excavated to construct the proposed channels and habitat within Pond Creek marsh will be used to supplement the material required to construct this habitat. Maritime forest, a rare habitat in New Jersey that is primarily found within Cape May County, will be constructed between valleys of dune restoration areas within the former Harbison Walker Magnesite facility. Dune restoration will be constructed by placing the excavated marsh material and capping it with 2-feet of clean sand from an off-site source. Additionally, portions of the former Harbison Walker Magnesite facility and the northern landfill within the project area will be re-graded and topped with a 6-inch layer of topsoil, which will be seeded and restored into coastal successional/old field habitat. In addition to the upland habitat restoration, the project has incorporated dune restoration areas and channel reinforcement at localized points and low spots around a key freshwater habitat known as Davey’s Lake located near the beach front of the project area.
Collaborating with multiple stakeholders, ONRR incorporated multiple wildlife viewing blind structures along an enhanced trail system to provide visitors with an array of visual opportunities that are rare and difficult to come by. The wildlife viewing structures include a bunker blind, a heron canopy viewing platform, two boardwalk systems with platforms, and seven 360º bird blind structures. Additional trail enhancements include a connective loop around the project area that utilizes the berm system to provide access through the marsh, a new pedestrian bridge spanning between the landfills on the project area and providing pedestrian benches and interpretive signs for public education opportunities. For maintenance requirements, the design includes a ford crossing in the channel immediately downstream of the proposed pedestrian bridge to provide access for heavy equipment and vehicles exceeding allowable bridge loads (H-10 truck loading or 90 pounds per square foot).
SCHEDULE: If all goes according to the current project timeline, ONRR anticipates construction to start in the Fall of 2023