Skip

NH Cooperative Salt Marsh Projects

New Hampshire Cooperative Salt Marsh Projects

The 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:

 

 

Awcomin Marsh, Rye, NH

Location map

This is available in document format for downloading. This document requires Adobe Acrobat.

Awcomin Salt Marsh Environmental Assessment

Awcomin Marsh had been diked and used as a spoil disposal site for the dredging of Rye Harbor in the early 1940's and again in the early 1960's. Approximately twelve acres of this site has been restored by breaching dikes and digging ditches to replace the original tidal creeks filled by spoil. Monitoring indicates a reduction in the invasive plant Phragmites australis.

The photos to the right show ditching done to restore the first twelve acres (Phase 1). Currently, Phase I is complete and Spartina alterniflora and other native species are regenerating.

Phase II was completed during the winter of 2003, which included removing the dredge spoil from 25 acres of salt marsh.

 

 

View out onto marsh at Awcomin

Ditching during Phase 1 of Awcomin Salt Marsh restoration

 

Beard's Creek, Durham, NH

View of the degraded Beard's Creek marshAt 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.Flashboards at the Beard's Creek culvert

The sewer line that crosses the creek system off Route 108 will have to be stabilized if the flashboards are removed and the pond emptied.  This project is in the early planning stage.  Several issues will have to be resolved for this project to go forward these include a change in the aesthetics of pond to a salt marsh, concerns about loss of the  crosses Beards Creek several hundred feet upstream of Route 108.  This site was being used in the 2000 NH Envirothon as a special problem potential mitigation site.

Additional Information:

 

Brown's River, Seabrook/Hampton Falls, NH

Location map

Old railroad bed with culvert restricting tidal flow.The tidal restriction at Brown's River was along an inactive railroad line at the boundary between Seabrook and Hampton Falls, New Hampshire.

The 48" culvert originally installed by the railroad was too small and the invert (bottom) too high to allow adequate tidal flow to approximately 41 acres of marsh.  The restrictive culvert is located on the property of the Seabrook Nuclear Power Station.

Dead Phragmites following the installation of an adequate culvert.The photograph above shows the old 48" culvert.  This picture was taken from the downstream side of the railroad embankment.

The fact that the water in the pipe is higher than the water in the creek indicates that the embankment is acting as a restriction to tidal flow. The railroad line is presently inactive and some of the track has been removed.

The project has been designed and funded, and is currently in the planning phase.  The plan is to replace the current culverts with a precast 5' x 7' culvert.

The photograph above right is looking upstream from the railroad embankment.  The periphery of the marsh is degrading as evidenced by the stand of Phragmites in the distance.

 

Cain's Brook, Seabrook, NH

the restrictive culvert at Cains Brook
Location map

A bridge on a private driveway was restricting tidal flow to approximately 17 acres of salt marsh.  This culvert was replaced in 1998 with a 5' x 7' cast concrete culvert.

The photo at the right shows the one restrictive culvert.

 

Drakeside Road, Hampton, NH

Location map

Drakeside Road marsh area after restoration of tidal flow.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 photo on the left shows the Phragmites has died due to the increased salt water flow into the area following the upgrading of the culvert.

   

Landing Road, Rye, NH

A restrictive culvert impairing salt marsh health at Landing Road.Location map

A section of abandoned town road restricted tidal flow to an 11 acre marsh adjacent to Landing Road in the town of Hampton. 

A new culvert was installed under a section of active road.  The picture on the right shows the original inadequate culvert.

   

Little River, Hampton and North Hampton, NH

Location map

Aerial photo of Little River. 1990Picture of Little River Salt Marsh in 1999, showing areas of degradation.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. 

The lack of an adequate connection with the ocean had also caused serious flooding problems because storm flows from the Little River did not have stable a outlet from the marsh.  The restrictive culvert did not allow for either adequate tidal flow into the marsh, or adequate drainage off the marsh after heavy rains.

Currently, almost the entire marsh has adequate tidal flow restored and this project has state and national awards.

More on the Little River Salt Marsh Restoration Project

 

Meadow Pond, Hampton, NH

Location map

View of Meadow Pond 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.

 

Odiorne State Park, Rye, NH

View of Odiorne State Park parking lot. 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 photo shows the boat ramp and kiosk for collecting park admissions.  Park visitors using the parking lot for beach access are forced to cross the salt marsh to get to the beach trail.

This salt marsh restoration project is in the early planning stage, was used in the 2000 NH Envirothon as a special problem potential mitigation site.

Additional Information:

 

Parson's Creek Marsh 

Natural deepening of the tidal creek at Parson's Creek.outlet to Parsons Creek at Concord Point before the installation of the new culvertThe 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 Wallis Road along with associated ditching and ditch cleaning.  A 5' x 7' culvert was installed under Marsh Road and the eroding bank of Parson's Creek was stabilized at Concord Point.  In the spring of 1999, the third culvert was installed under Route 1A near Wallis Sands to complete the project.

The top left photo shows the natural outlet to the Parsons Creek Marsh at Concord Point in Rye, photographed in 1997 before the installation of the Wallace Road culvert.

Dead cattails at the Parson's Creek marsh.Revegetation of native salt marsh grasses at Parson's Creek marsh.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.

The third photo shows dead narrow leaf cattails killed by increased tidal  rapidly deteriorating due to lack of tidal flow.  Right is a shot of Spartina alterniflora (light green) that has naturally revegetated "rotten panne" following restoration of tidal flow.  We have had to do almost no planting of Spartina spp. in New Hampshire restorations because of the tremendous natural revegetation.

Additional Information:

 

Parson's Creek - Marsh Road, Rye, NH

Degraded salt marsh at Marsh RoadA 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.  

 

 

Parson's Creek - Wallis Road, Rye, NH

Location of old culvert under Wallace Road.A new culvert was installed during the winter if 1998 - 1999 under Wallis 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.  

Engineering surveys and hydrology studies indicated the need for the installation of twin 12 foot concrete box culverts.  These culverts are precast, and delivered by truck and installed  in sections by a large crane.  

Canoers in the new tidal creek at Wallace Road.Because the new culverts are approximately 200 feet down the street from

New excavated tidal creek at Wallace Road.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!

 

Parson's Creek - Wallis Sands, Rye, NH

View of excavated area for the new 5' x 7' culvert.Installation of a concrete section of the new culvert at Route 1A.This project involved replacing the original 18 inch concrete pipe culvert under Route 1A just south of the Wallis 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.  

 The enlarged culvert at Wallis Sands allows increased flow to the portion of the marsh that feeds this culvert. This culvert in concert with the new culvert at Wallis Road will greatly increase tidal flow to the degraded marsh south of the Wallis Sands parking lot.   

 

 

Rye Harbor - Harbor Road, Rye, NH

Location map

Harbor Road marsh area completely overtaken by Phragmites.Harbor Road marsh after removal of sediment, with drastic reduction in Phragmites.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.

Photos to the top right show the the marsh completely taken over by the invasive plant Phragmites, after removal of sediment (left).

 

Rye Harbor - Locke Road, Rye, NH

Location map

Inadequate culvert under Locke Road prior to restoration project.New 5' x 7' concrete box culvert under Locke Road.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.

Excavation of tidal ditches to restore salt water to degraded marsh.Reestablishment of salt marsh vegetation two years after completion of the project.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.

 

Sandy Point, Stratham, NH

Volunteer working at the Sandy PointIn 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.

Additional ditches and control of invasive species may be needed in the future and occasional maintenance of the ditches due to sloughing of the degraded marsh surface.  This problem will probably be reduced in the future as the marsh stabilizes.

 

Stuart Farm, Stratham, NH

Location map

Aerial photo of the Stuart Farm, Stratham, NHIn 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. 

In 1993, a large metal arch culvert was installed restoring tidal flow to the marsh. The immediate result was a die off of many fresh water plants. Further monitoring indicates that salt marsh vegetation is returning. Anadromous herring have also been seen in the restored marsh.

Aerial photo of the Stuart Farm on the Great Bay Estuary.  Stuart Farm has also been protected by the Farm and Ranch Lands Protection Program (FRPP).