Since 1900, global sea levels have risen by an average of eight inches. Sea levels vary locally relative to land due to currents, wind, and other factors. The sea level along the eastern United States is rising at its fastest rate in two thousand years.

The rate of change along the coast of the north Atlantic Ocean, including the Cape Ann coastline, is expected to continue rising faster than the global average.¹ In the face of rapid sea level rise, Cape Ann requires coastal armoring infrastructures to protect against flooding.

Conventional “gray” infrastructure, including breakwaters, bulkheads and jetties, have high maintenance costs and increase erosion and scouring at other locations along the coast. Pairing gray infrastructure with “green” infrastructure, such as barrier beaches, dunes and marshland, can reduce maintenance costs, buffer communities from flooding, and provide additional social and environmental benefits.²

There are four proposed coastal armoring initiatives across Cape Ann. These projects protect select cultural, economic, and institutional resources throughout the region.

The Gloucester Outer Harbor Hurricane Barrier is a hurricane barrier and gate system deployed at three locations in Gloucester. A stone barrier with a surge gate runs across the Outer Harbor. A surge gate on the Andrew A. Piatt bridge and tidal gate on Route 128 slow water flowing through the Annisquam River. Tidal gates on Thatcher Road protect against flooding from Good Harbor marsh.³

While the barrier protects Gloucester’s Inner Harbor, civic districts, and commercial district in the event of storm surge, it does not protect against sea level rise.

The proposed barrier protects 1,041 structures and key cultural institutions in Gloucester, including the working waterfront.

The proposal also restores the Good Harbor marsh system, including raising Thatcher Road and installing tidal gates so water can flow through the marsh.

As an alternative, a smaller stone hurricane barrier system in Gloucester’s Inner Harbor protects the downtown area from storm surge.

The one-thousand-foot barrier spans from Fort Point in the Inner Harbor to The Paint Factory on Rocky Neck. It includes surge gates to let vessels in and out of the Inner Harbor.⁴ A smaller, 580-foot barrier with tidal gates spans Rocky Neck Beach. Individual owners elevate seawalls and bulkheads around the perimeter of the Inner Harbor.⁵

The barrier protects 199 structures that may be damaged by storm surge by 2030. An elevated walkway along the top of the barriers creates a new harbor walk for coastal access.⁶

Manchester Harbor was a muddy estuary before it was dredged in the seventeenth century. The Inner and Outer Harbor were separated when railway tracks were laid between them in 1847.

To protect the Inner Harbor and downtown areas from flooding, the proposed Manchester-by-the-Sea storm surge barrier sits at the mouth of the harbor from Proctor Street to Tuck’s Point.⁷ The barrier includes surge gates to let boats into the harbor.

A secondary set of surge gates replaces the MBTA Bascule Bridge along the elevated tracks.⁸⁹¹⁰ The elevated tracks and surge gate also protect the trunk cable that delivers electricity to Cape Ann. The cable passes through downtown Manchester-by-the-Sea, and is at extremely high risk of damage during flooding and storm surge events.¹¹

The Manchester Surge Barrier protects 105 structures that face projected storm surge damage by 2030. The marsh in Central Pond is restored to serve as a retention pond during periods of heavy flooding. The saltmarshes around Day’s Creek and Whittier’s Creek are also raised with sediment and replanted.¹²

Rockport’s coast has historically featured granite breakwaters, including the Sandy Bay Breakwater, a proposed nine-thousand-foot structure that was abandoned in the early 1900s.¹³

Now a long stone breakwater extends from Granite Pier to Sandy Bay Ledge to the existing Bearskin Neck breakwater, protecting downtown Rockport. An additional set of surge gates across the inner harbor protect the working waterfront while allowing boats to pass through.

The armoring project protects 135 structures against storm surge. Eel grass is planted in the shallow, calm water behind the breakwater.¹⁴

Residents amble over the Harbor Walk, part of the Inner Harbor hurricane barrier across Rocky Neck Beach.

The elevated MBTA Commuter Rail runs across the secondary set of surge gates in Manchester’s Inner Harbor. The raised berm protects the Village Core.

Seawalls and bulkheads are raised by individual property owners along Smith Cove.

As the Annisquam estuary rises, a dike is constructed from the Cut Bridge at Blynman Canal to Gloucester High School. The dike and revetment protect the high school from nuisance flooding.

Each of these proposals protect limited areas along the coast and can offset erosion and scouring in other locations. Additional adaptation measures alongside armoring and planting will be required to defend against sea level rise.