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New Hampshire Cooperative Salt Marsh ProjectsThe following are examples of the tremendous success that NH NRCS and our partners have had with salt marsh restoration along the New Hampshire coastline. Projects that have been completed, are currently in progress, or have been identified in the "Evaluation of Restorable Salt Marshes in New Hampshire" (available for download on the Ecosystem Restoration web site) are included. For the vast majority of completed projects, NH NRCS provided biological/ecological guidance on native ecosystem restoration, engineering technical assistance on salt marsh hydrology and flood damage reduction, and cost-sharing through the Wetlands Reserve Program.
Click below for links on this page for:
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At some time during the early 1970's, flashboards were installed in the Beards Creek culvert under
Route 108 in Durham.
This impounded the creek and blocked tidal flow upstream. The result was a loss of approximately 16
acres of salt marsh. Restoration of the former salt marsh will require removing
the flashboards and installing a larger culvert at Coe Drive upstream of Route 108.
The tidal restriction at Brown's River was along an inactive railroad line at the boundary between Seabrook
and Hampton Falls, New Hampshire.
The photograph
above shows the old 48" culvert.
This picture was taken from the downstream side of the railroad embankment.
An inadequate road culvert was replaced with a 5' x 7'
concrete
box culvert during the fall of 1996. This replacement restored tidal flow to approximately
22 acres of salt marsh. 
The Little River Salt Marsh is a back barrier marsh lying between
Little Boar’s Head in North Hampton and a rocky headland just south of North Shore
road in Hampton. A USDA
Soil Survey indicated that originally the marsh was approximately
193 acres in size. By the 1990's most of the original marsh had deteriorated
due to severely restricted tidal flow to the
marsh. 
A storm in the fall of 1996 washed out a culvert
which restricted tidal flow to Meadow Pond, a highly degraded salt marsh. The
town of Hampton replaced this culvert with 24 foot concrete arch culvert. This new
culvert restores adequate tidal flow to approximately 117 acres of degraded salt marsh.
The photo shows a stand of the invasive plant Phragmites that was killed
after restoration of tidal flow.
About 1979,
a parking lot and boat ramp were constructed at Odiorne State Park.
They were built on approximately 0.5 acres of salt marsh. In 1988 the parking lot
was expanded toward Route 1A on upland adjacent to the original parking lot. 
The Parson's Creek project
involved replacing several road culverts, and installing ditches to restore
adequate tidal flow to approximately 150 acres of marsh. In the fall
and winter of 1997-98, twin 6' x 12' concrete box culverts were installed under
This second picture
(top right) was taken during the summer of 1999, two growing seasons
following restoration of adequate tidal flow. The channel is being cut deeper and
narrower (hence the exposed mud flat to the left). The reason for this is that the
tidal creeks in this area of the marsh had become wide and shallow because of lower flows
and a softening of the marsh surface (peat degradation). Increased flows are causing
the tidal creek to cut narrower and deeper as indicated by the deeper channel to the
right. The width and depth of the new channel is comparable to natural tidal creeks
in marshes of this size and watershed.
A new culvert was installed under Marsh
Road in 1998 to replaced an 18" metal culvert that was no longer functioning.
Essentially, all tidal flow had been blocked to approximately 4 acres of marsh north of
Marsh Road. This area of the marsh was almost totally degraded (photo to
right) to 100% narrow leaf cattail. 
A new culvert was installed during the winter if 1998 -
1999 under Wallace Road, which was one of the main obstructions to tidal
flow in the Parson's Creek Marsh. The red arrow in the photo at top
shows the location of original culvert. The new culverts were
installed in the foreground away from the buildings at the edge of the marsh. 
Because the new culverts are
approximately 200 feet down the street
from
The photo on the left shows a father and son using the new
tidal creek for canoeing. Recreation is also one of the benefits of
restored salt marshes!
This
project involved replacing the original 18 inch concrete pipe culvert under Route 1A
just south of the Wallace Sands State Park. The installation of a
new 5' x 7' concrete box culvert
in April of 1999 (photos, right) took about three days, from digging the ditch to repaving. 
A two acre portion of the
Rye Harbor salt marsh had been cut off from tidal flow by a road constructed from Harbor Road
to the public boat launch ramp. This area was also used as a spoil disposal area
during harbor dredging in the early 1960's. As a result the area was not only denied
tidal flow but approximately 1.5 feet of sediment covered the original marsh surface.
As typically happens in these circumstances the marsh was completely taken over by
invasive species, primarily Phragmites. 
Three inadequate road culverts which
restricted tidal flow to approximately 37 acres of degraded salt marsh were
replaced between 1994 and 1997. The first was an 18" culvert, under a private drive, replaced in 1994 with a 40"
squashed corrugated metal pipe. The second, a 40" corrugated pipe under Locke Road,
was replaced in 1995 with a 9' x 12' concrete box culvert. The third and last, an 18" corrugated metal pipe under U.S. Route 1A, was replaced by a 5' x 7' concrete box
culvert in the fall of 1996. During the spring of 1997 connecting ditches were dug to
restore tidal flow to critical portions of the marsh (photo, lower right). Note the use of planks to reduce damage to the salt marsh
surface and soil structure. Some existing ditches were also
cleaned of sediment. Spoil and rocks from from previous ditching was also removed from the
surface of the marsh. 
Spartina alterniflora and Salicornia
spp. were already
reestablishing by 1998 (photo, right). In addition to the regrowth of native salt marsh plants there has been a
reduction of the invasive species Phragmites in the restored areas of the marsh.
While some Phragmites persists on the marsh fringe and may have to be chemically treated,
the reintrodution of tidal flow has reduced its height and vigor, and undoubtedly
prevented its further spread in the marsh.
In 1994, volunteers
cleaned sediment and debris from a tidal creek and side ditches at the Visitors
Center of the Great Bay Estuarine Research Reserve. The photo to the right
shows a volunteer working at Sandy Point where plywood was
used to prevent damage to the marsh.
In the early 1960's, a wooden bridge along the Stuart Farm access road was replaced with an 18" tide-gated culvert.
This restricted tidal flow to an 12 acre tidal wetland. This resulted in a dramatic change
in vegetation from a Spartina dominated salt marsh to a fresh water marsh/shrub wetland. 
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