Prime Hook plan to restore marsh nearing start
More than five years after the dunes near Prime Hook National Wildlife Refuge were first breached by waters from the Delaware Bay, a massive effort to restore the preserve and hold back rising seas from a vulnerable area of the southern Delaware coast is about to begin.The federally funded $38 million project, now awaiting its final permits, is expected to swing into action in July with the dredging of channels to allow saltwater from the bay to flow out of the refuge, creating conditions in which the naturally occurring salt marsh can be restored.
Subsequent phases will include the closing of four breaches in the dunes that protect the refuge from the bay; the pumping of dredged sand and mud on to marshes that are being drowned by increasing inflows of saltwater; the removal of sections of local road that impede the flow of water within the preserve, and the planting of grasses that will re-establish the marsh.
Wildlife refuge under threat
The goal, as described in a detailed Environmental Assessment published by the U.S. Fish & Wildlife Service (FWS) in February, is to recreate conditions in which wildlife, especially migratory birds, can thrive, in keeping with the original aims of the 10,000-acre refuge when it opened in 1963.
That mission was severely compromised by freshwater impoundments which were built in the early 1980s with the intention of attracting more migrating birds but which have since been inundated by sea water, flooding marshes and creating wide stretches of open water.
The process of saltwater inundation got a lot worse starting in 2006 when the first overwash – in which storms or high tides drive bay waters across the dunes but they don’t return to the bay – appeared near Fowler’s Beach at the northern edge of the refuge.
Major storms in 2009 and 2011, followed by Superstorm Sandy in 2012, blew more holes in the dunes, worsening the flooding during high tides and nor’easters, and making it even harder for the refuge to fulfill its mission of protecting wildlife.
Since the FWS issued a preliminary report outlining restoration options in 2012, conditions have worsened in 11 of 16 functions measured. They include increased open-water inundation; further losses of wildlife habitat, and more loss of vegetation because of flooding, according to the 125-page Environmental Assessment.
One-of-a-kind project to restore habitat
To prevent further losses, the solution is to restore the refuge by rebuilding the marsh and filling the breaches in what will be the biggest marsh restoration on the East Coast, according to Bart Wilson, the restoration project manager.
“We are breaking new ground,” Wilson told Delaware Public Media .
The project, which must finish by October 2016 to meet federal funding requirements, will also distinguish itself by using techniques that have not been used on a large scale before, and so may set a precedent for other areas that are seeking to protect wetlands from rising seas, Wilson said.
“We’re trying to bring a whole bunch of pieces together,” he said. Techniques include “thin-layer application” which spreads dredged mud and sand over mudflats or marshes to help raise their level, prepare them for planting, and make them more resilient to sea-level rise.
“Historically you would put it in an upland disposal area or dump it out in the bay somewhere, and now we’re saying ‘let’s keep it in the system and use it,’” Wilson said, referring to the dredged material.
Dredged sand and mud have recently been used on a much smaller 21-acre portion of a site at Pepper Creek near Dagsboro where the Delaware Department of Natural Resources and Environmental Control sprayed the material over a marsh in what Wilson called a “proof of concept.”
By raising the Prime Hook marsh and lowering the water, the project aims to repair about 3,000 acres of degraded habitat, of which about a third would be revegetated within five to eight years after being planted with marsh grasses.
In the process, it’s likely to become a template for how to protect coastal areas from sea-level rise, Wilson said. “Turning this back to salt marsh builds sustainability,” he said.
And its approach to dealing with saltwater-flooded impoundments will be watched closely by other authorities in Delaware and elsewhere who are struggling with how to manage their own coastal impoundments as sea levels rise, Wilson predicted.
Although Prime Hook’s impoundments succeeded in their goal of attracting more migrating birds during their first couple of decades, they severely degraded the habitat when they filled with sea water starting in the mid-2000s, and so are now the focus of the restoration plan, he said.
“It came to the point where sea-level rise and coastal erosion made the [dunes] smaller and smaller, and then they breached, and we had catastrophic loss,” he said.
Plan may help local communities
While the project is focused on restoring wildlife habitat, it will also benefit nearby local communities which have suffered years of flooding because of the breached dunes, and whose residents have accused federal officials of excessive delay in fixing them.
“It’s going to help,” said Ron Goodwin, who owns a summer home at Prime Hook Beach, a community on the bay side of the refuge where residents regularly deal with flooded roads and yards during high tides and northeast winds.
Goodwin, one of about 40 residents who attended a public meeting about the restoration plan at the refuge headquarters on Wednesday, said he hoped that filling the dune breaches will end the regular flooding of Prime Hook Road, a narrow ribbon of blacktop between two of the impoundments, and the community’s only link with the outside world.
But he questioned whether the plan does enough to allow water to flow past Broadkill Road on the southern edge of the refuge. He said the road acts as a “dam” and argued that the FWS doesn’t have the authority to change the flows there.
A new channel will be dredged to improve water flow between the two impoundments closest to Prime Hook Beach, and a new bridge, built by the Delaware Department of Transportation, will take Prime Hook Road across the channel.
Steve Bennett, a farmer who owns over 150 acres near Fowler’s Beach Road on the north side of the refuge, welcomed the plan as his best chance of reclaiming land that he has recently lost to saltwater intrusion.
Bennett said about 30 acres where he would normally grow soybeans and grains have been regularly flooded by sea water over the last three years, and another 15 acres of his woodland has been destroyed by the salt.
“If it keeps happening like it is, I’m going to lose the entire farm,” said Bennett, whose family has been farming the land for about 150 years.
While the plan may help local communities, its main focus is to restore wildlife habitat, said Al Rizzo, who manages Prime Hook and the Bombay Hook National Wildlife Refuge at Smyrna.
“The reality of it is that we are doing the best we can for the refuge, and if you guys benefit, we are thrilled,” Rizzo told the meeting.
He stressed that the plan is based on the best available science and assumes a normal range of climatic and tidal conditions but warned that it may not hold up under exceptional storms like Superstorm Sandy.
“If we get hit by a Category 4 hurricane, all bets are off,” he said.