Marshfield-03
Marshfield, South River
42.093107, -70.700388
Technical Specifications
Basic Properties
- Type
- Flap Gate
- Material
- Wood
- Control
- —
- Condition
- —
- Geometry
- Rectangular
- Status
- Inactive
- Number of Gates
- 1
Operator & Management
- Operator Type
- PUBLIC
- Operator
- Town of Marshfield DPW
- Permits
- —
- Purpose
- Flood Protection
Dimensions & Elevations
- Dimensions
- 4.167ft diameter, 4.167ft height
- Invert Elevation
- —
- Installation Date
- —
- Tidal Influence
- —
Culvert Details
- Restriction Type
- Roadway
- Geometry
- Circular
- Material
- Concrete
- Bottom Material
- —
- Number of Pipes
- 1
- Dimensions
- 2.5ft diameter
- Condition
- —
- Comments
- Culvert under Rt139 / River side has large stand of narrow leaf cattail / large tide-gate system on the upstream side of Rt.140
Salt Marsh Field Assessment Results
Comprehensive field assessment dataPhysical Conditions Assessment
Channel Conditions
- Channel Alteration and Ditching
- Limited (<133 ft/acre)
- Channel Constriction
- Wider than channel_
- Channel Erosion
- Moderate (10-60% of bank)
- Sediment Deposits
- None
Blockages
- Debris Blockages
- None
- Evidence of Overtopping
- No
Ecological Assessment
Habitat Observations
- Ecological Impairment due to Tide Gate
- Moderate
- Crab Burrow Intensity
- None
- Ponding and Die-off Depressions
- None
- Phragmites Present
- Severe (>60%)
Invasive Species
- Upstream Invasive Species
- Yes
- Downstream Invasive Species
- Yes
- Invasive Species Notes
- Upstream is monoculture of phragmites
General Comments
Upstream channel width and dense phragmites upstream indicate moderate constriction. Downstream end is freshwater wetland with mix of phragmites and cattails so tidal exchange salinity maybe already be limited on the incoming tide. Previous analysis indicated that enlarging culvert is infeasible and tide gate is already managed fully open due to flapper being broken.Habitat Transects
First Transect (50 yards upstream of tide gate)
No data
Second Transect (150 yards upstream of tide gate)
No data
Third Transect (300 yards upstream of tide gate)
No data
Restoration Potential
Assessment
- Salt Marsh Impairment due to Tidal Restriction
- Moderate
- Potential Extent of Marsh Restoration
- Moderate
- Implementation Feasibility
- High
- Restoration Priority
- High
- Recommended Improvement Type
- O&M and Infrastructure
Notes
Site shows moderate salt marsh impairment due to restricted tidal flow. Replacement with self-regulating tide gate could restore approximately 5-8 acres of degraded marsh habitat. Good access for construction equipment. Regional coordination completed with town DPW and conservation commission.Historical Records
Environmental Data
- Invasive Species
- Yes
- Restoration Status
- —
- Invasive Comments
- Phragmites
- Restoration Comments
- Flap has rusted off within vault, culvert is now open. DER investigated with Town and Jason Burtner back in 2012. Recent sewer line installation in Ocean Street limits opportunities for increasing culvert size. Examination of LiDAR and tide data suggests little risk of leaving flap off. DER has tide and Lidar analysis for site.
- Upstream Area
- Salt Marsh: 5-10 acres
Notes & Comments
- General Comments
- —
- Operation Plan
- No
- Operation Comments
- —
- Gate Comments
- —
- Elevation Comments
- —
- Visit Comments
- —
- Other Comments
- —
- External Data Comments
- —
Part of the Massachusetts Bays Program© 2026 Massachusetts Bays Program. Monitoring tidegates across Massachusetts.