A single 5-foot diameter culvert under Black Point Road had restricted tidal flow to the upper marsh by approximately two-thirds, causing an alteration of the natural hydrology and vegetation of the marsh on the northeast side of the road (Normandeau, 2005).
Restoration Overview
A restoration design was developed by the partners to supplement flow through the existing 60-inch diameter culvert under Black Point Road with two 72-inch culverts. The Maine Department of Transportation finished the installation of the new culverts in November of 2006.
Following the construction phase, on behalf of the Friends of Scarborough Marsh, Normandeau Associates conducted a 5-year monitoring program to collect data in year one, three and five post-construction.
Status - Completed
Scarborough Marsh restoration partners continue to work together,
and have completed the fourth major salt marsh restoration
project in Scarborough Marsh Wildlife Management Area. This
most recent project promises to help restore the ecological
health of the 114 acre section of the Libby River Marsh upstream
from the Black Point Road (Route 207).
The first-year post-construction data (2007) showed the tidal range in the restricted marsh was reduced to 81% of downstream conditions immediately above Black Point Road and to 77% at mid-marsh. This represents an approximately 20% improvement over pre-construction conditions. This increase of tidal water through the culverts has also increased salinity and hydroperiod (the pattern of flooding events) on the marsh surface, which may, over time, result in restoration of salt marsh habitat and improved wildlife habitat.
According to Wayne Munroe, District Conservationist for the
USDA --Natural Resources Conservation Service , “This
important restoration project provides marvelous benefits
for the Libby River’s tidal wetlands and will provide
for greater fish and wildlife value, as well as invasive species
control.” >>MORE
The final post-construction surveys are planned for 2011 when Normandeau Associates will monitor the hydrology (surface water and ground water) and vegetation at several stations.
