TideGateway

Marshfield-01B

Marshfield, Green Harbor

42.089930, -70.645111

Technical Specifications

Basic Properties

Type
Flap Gate
Material
Metal
Condition
Good
Geometry
Rectangular
Status
Active
Number of Gates
0

Operator & Management

Operator Type
PUBLIC
Operator
Town of Marshfield
Permits
ACOE
Purpose
Flood Protection

Dimensions & Elevations

Dimensions
4ft diameter, 3ft height

Culvert Details

Restriction Type
Roadway
Geometry
Rectangular
Material
Concrete
Number of Pipes
0
Dimensions
4ft diameter, 3ft height
Condition
Good
Comments
Both culverts appeared to be in good condition. The upstream wingwall was in good condition, but appeared to be starting to slightly separate from the headwall.

2024 Field Survey Results

Comprehensive field assessment conducted in 2024

Physical Conditions Assessment

Channel Conditions

Channel Alteration
Moderate (133-398 ft/acre)
Channel Constriction
Narrower than channel
Channel Erosion
Little (<10% of bank)
Sediment Deposits
None

Blockages & Issues

Debris Blockages
None
Evidence of Overtopping
No

Transect Measurements

50 Yards

Open Water
0
Salt Marsh
69
Brackish
20
Freshwater
0
Ditch
160
Unvegetated
0

150 Yards

Open Water
0
Salt Marsh
167
Brackish
9
Freshwater
0
Ditch
24
Unvegetated
0

300 Yards

Open Water
0
Salt Marsh
0
Brackish
0
Freshwater
0
Ditch
0
Unvegetated
0

Ecological Assessment

Habitat Observations

Crab Burrow Intensity
None
Ponding Depressions
Moderate (10-60% of marsh platf
Phragmites Present
Moderate (10-60%)
Ecological Impairment
Moderate

Invasive Species

Upstream Invasive Species
Yes
Downstream Invasive Species
Yes
Invasive Species Notes
Phragmites on fringe and starting to creep into high marsh.
Additional Comments (2024)
Tide gate submerged on incoming tide. Not all factors could be completely assessed, however lack of low marsh community, severity of ponding and lack of sediment exchange indicate tidal restriction is present.

Historical Records

Legacy data from previous surveys and documentation

Environmental Data

Invasive Species
Yes
Restoration Status
In-Progress
Invasive Comments
Upstream marsh was comprised of a mixture of low and high marsh with fringing phragmites.
Upstream Area
Salt Marsh: 10-15 acres

Notes & Comments

General Comments
Site is located directly off of Town pier Road and easily accessible. Note that Jason Burtner can provide permitting drawings and other relevant files and site information to further flesh out attributes. Permitted together with Marshfield 02.
Gate Comments
There were two tide gates installed at this location. A metal self-regulating tide (SRT) gate was installed to the west (Marshfield-01A) and a metal flap gate was installed to the east (Marshfield-01B). The self-regulating tide gate was in fair condition and was inoperable; the bottom float which allows the tide gate to open was missing. As a result, it appeared that the gate was currently operating as a flap gate and limiting upstream tidal exchange. A hand operated winch and strap had been installed to operate the SRT and the strap was weathered. Additionally, the SRT’s breather was clogged with debris and some leakage was observed around the flange connection to the headwall. The metal flap gate appeared to be in good condition and operable.
Elevation Comments
See "General Comments". Invert elevation and extent of downstream tidal influence can be located on permitted plans to be uploaded. Staining was not apparent on the upstream headwall (i.e., it was higher), so extent of upstream tidal influence could not be assessed.
External Data Comments
US ACOE NAE-2004-3126 Green Harbor Tide Gates Permit Application 10.2.2002 US ACOE NAE-2004-3126 Green Harbor Tide Gates Permit 12.3.2004 US ACOE NAE-2004-3126 Green Harbor Tide Gates Operation and Maintenance Plan 12.3.2004
© 2025 Massachusetts Bays Program. Monitoring tidegates across Massachusetts.