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St Croix River High Salt Marsh and Floodplain Wetland Restoration

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                               St. Croix River High Salt Marsh and
                            Floodplain Wetland Restoration Project

The St. Croix River is a tidal river system
that empties into the Minas Basin, part of
the greater Bay of Fundy. The restoration
project consisted of four sections of
dykeland along the St. Croix River where it
borders the TransCanada Highway (101).
The goal was to restore a more natural
hydrology to the sites, enabling the re-
establishment of tidal wetland habitat
conditions. There is a pre- and post-
restoration long-term monitoring program
associated with this project.

Monitoring Program: 2006 – 2015
Location: Hants County, Nova Scotia

Client: Nova Scotia Department of
       Transportation & Infrastructure
       Renewal (NSTIR)
       Dr. Bob Pett
       902.424.4082
       pettrj@gov.ns.ca

Project Managers: Tony M. Bowron
                   Nancy C. Neatt
Key Personnel: Jennie Graham (CBWES)
               Dr. Jeremy Lundholm (SMU1)
               Dr. Danika van Proosdij (SMU)

Project Details: CBWES was commissioned by NSTIR in
2006 to conduct a restoration feasibility study, and to develop
the restoration design in order to restore tidal flow and wetland habitat conditions to the four quadrants of
dykeland bordering Highway 101 where it crosses the St. Croix River. It was determined that if the dykes were
partially removed (breached) that the resulting periodic flooding of the sites by tidal waters would have the
potential to create a very dynamic and productive wetland habitat. Dyke removal, excavation of tidal channels
and ponds, and the re-activation of tidal creek networks, would re-establish a tidally influenced brackish (high salt

1   SMU – Saint Mary’s University

CBWES Inc.                                        www.cbwes.com                                                2010
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marsh) and floodplain wetland complex. It was determined that restoration activities would re-establish the four
study sites as part of the Thumbhill Creek and St. Croix River coastal floodplain ecosystem A long-term
monitoring program was developed for the project with baseline ecological monitoring taking place in 2007 and
2008 in advance of restoration in 2009.

Long-term Monitoring Program: The monitoring
program utilized for this project was adopted and
adapted by CBWES from a set of regional protocols
(The Global Program of Action Coalition for the Gulf of
Maine Regional Monitoring Protocol2) developed for
use as part of tidal wetland restoration projects in the
Gulf of Maine and Bay of Fundy.

Indicators used to assess this project:
Geospatial Attributes (digital elevation model, habitat
mapping); Hydrology (hydroperiod, water table depth, water quality); Soils and Sediments (pore water salinity,
soil characteristics, sediment accretion and elevation); Vegetation; Nekton; and Benthic and Other Aquatic
Invertebrates.

                                                    Restoration Design: During the restoration design phase
                                                    of the St. Croix project a set of preliminary hydraulic equations
                                                    were established for the Bay of Fundy region using the
                                                    methods laid out by Williams et al. (20023) and used to
                                                    determine the appropriate width and depth of excavated creeks
                                                    and breaches. These equations were further tested and refined
                                                    through observations and application to a previously restored
                                                    salt marsh (Walton River). The results of this preliminary
                                                    work brought up several questions which will be addressed by
                                                    CBWES through the development of a GIS-based model and
                                                    protocol for future use in the design of marsh restoration
                                                    projects in macro-tidal environments.

Project Reports:
Annual reports are available for download at
www.gov.ns.ca/tran/enviroservices/enviroSaltMarsh.asp or by
contacting CBWES at info@cbwes.com.

Most Recent Project Report:

Bowron, T.M., N.C. Neatt, J.M. Graham, D. van Proosdij, and J.
Lundholm. 2010. Restoration and Monitoring Report for the St.
Croix River High Salt Marsh and Floodplain Wetland
Restoration Project. Report prepared for Nova Scotia
Department of Transportation and Infrastructure Renewal.
CBWES Inc. Publication No.20. Halifax, NS.



2 Neckles, H.A., M. Dionne, D.M. Burdick, C.T. Roman, R. Buchsbaum, and E. Hutchins. 2002. A Monitoring Protocol to

Assess Tidal Restoration of Salt Marshes on Local and Regional Scales. Restoration Ecology, 10(3): 556 – 563.
3
  Williams, P.B; Orr, M.K. and N.J. Garrity. 2002. Hydraulic geometry: a geomorphic design tool for tidal marsh channel
evolution in wetland restoration projects. Restoration Ecology 10(3): 577-590.


CBWES Inc.                                         www.cbwes.com                                                 2010

				
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