Seawall & Bulkhead Guide: Portsmouth, Rhode Island

A Town That Is Mostly Water -- Three Different Shorelines, Not One

Per Wikipedia, Portsmouth's total area is 59.3 square miles (154 km²), of which just 23.2 square miles (39.14%) is land and 36.1 square miles (60.86%) is water. That is an unusually high water share for a town of this size, and it is not a technicality -- it reflects real geography, since Portsmouth's boundaries extend across Narragansett Bay to include Prudence Island (the largest, with its own year-round community and ferry access), Patience Island, Hope Island, and Hog Island, well beyond the Aquidneck Island mainland most buyers picture.

That geography means "waterfront" in Portsmouth is not one uniform edge. There is the Sakonnet River side to the east, connecting to Tiverton via the Sakonnet River Bridge; the Narragansett Bay and Mount Hope Bay side to the west and north, connecting to Bristol via the Mount Hope Bridge; and the genuinely offshore bay-island parcels reachable only by ferry or private boat. A seawall or bulkhead decision looks different on each of those three edges, and none of them should be treated as interchangeable with the others.

What a Seawall, Bulkhead, and Revetment Actually Are

A seawall is typically a vertical or near-vertical wall -- concrete, steel, or masonry -- built to block wave energy directly at the shoreline. A bulkhead is usually a lighter structure, often timber, vinyl, or steel sheet piling, built mainly to retain soil and hold a property line rather than absorb heavy surf. A revetment is a sloped facing of armor stone or riprap laid against an eroding bank, meant to dissipate wave energy across an angled surface instead of reflecting it off a vertical face. Which of those, if any, makes sense for a given Portsmouth parcel depends heavily on which of the town's three shoreline types it sits on -- river, bay, or island -- and on site-specific engineering that this page cannot substitute for.

Why It Matters Here: The Sakonnet River Bridge and Rhode Island's Own Storm-Surge Data

Rhode Island's Division of Statewide Planning has published current, town-specific storm-surge and sea-level-rise projections for Portsmouth, and one figure in particular illustrates why shoreline exposure is a live concern in this specific stretch of the state: under a 7-foot sea-level-rise scenario, the Sakonnet River Bridge is flagged with "-84 inches of freeboard" -- meaning the bridge would have substantially less clearance than it needs under that projection. That is a bridge-clearance issue, not a private-property seawall issue, but it is a genuinely useful illustration of the kind of infrastructure-level exposure this stretch of Aquidneck Island carries, and it is reasonable to assume nearby waterfront and near-waterfront parcels share some of that same exposure.

The same state data names specific vulnerable roads worth knowing: Boyds Lane, Narragansett Avenue, Neck Farm Road, Common Fence Point Boulevard, and Park Avenue all show documented linear-foot exposure under the state's modeled scenarios. None of that is a statement about any specific parcel's flood-zone status or the need for a seawall on any one property -- but it does suggest, in general terms, where waterfront and near-waterfront hardening questions are most likely to come up in Portsmouth, and it is worth knowing these road names before assuming shoreline risk is spread evenly across town.

Island Park: A Reminder of What Unmitigated Storm Surge Can Do Here

Portsmouth has its own dated, local illustration of why shoreline protection is not an abstract question along this particular stretch of coast. Island Park was a real amusement park that operated on the Portsmouth shore of the Sakonnet River from 1897 until September 21, 1938, when a wall of water roughly 12 feet high surged up the river during that year's hurricane and permanently destroyed it. Today Island Park survives only as a neighborhood and beach-area name -- no trace of the park remains. That history is not a seawall story in itself, but it is a real, specific reminder of what unmitigated storm surge has already done once along this same river, and it is worth keeping in mind when weighing shoreline exposure anywhere near the Sakonnet River side of town.

What This Page Cannot Tell You

No specific current seawall or bulkhead permitting requirements for Portsmouth parcels, no typical construction cost, and no Portsmouth-specific CRMC regulation beyond the general fact that CRMC is the state's coastal permitting authority were confirmed in the research behind this page -- none of those figures are invented here. This page also does not identify any specific existing private seawall, bulkhead, or revetment anywhere in Portsmouth; no town-wide inventory of those structures was found. Portsmouth's property tax rate, by contrast, is confirmed: $13.28 per $1,000 of assessed value for residential real estate, FY2026, per the Rhode Island Division of Municipal Finance -- though it should still be reconfirmed with the Tax Assessor's office in case a newer tax roll has since taken effect.

What can be said is general and directional, not parcel-specific: any private seawall, bulkhead, or revetment construction in Portsmouth's regulated coastal zone -- whether on the Sakonnet River side, the Narragansett Bay/Mount Hope Bay side, or one of the bay islands -- would be expected to require review from Rhode Island's Coastal Resources Management Council (CRMC), the state agency that regulates coastal structures statewide, on top of whatever local permitting the Town of Portsmouth applies. Confirm the specific process, fees, and timeline directly with CRMC and with Portsmouth's own building or planning office before assuming anything about cost or approval.

Practical Takeaways for a Portsmouth Waterfront Buyer or Owner

If you are evaluating a property on Portsmouth's Sakonnet River side, keep the Sakonnet River Bridge's documented "-84 inches of freeboard" figure and the 1938 Island Park story in mind as real, sourced context for that stretch of shoreline -- not as a prediction about any specific parcel, but as evidence that this river has produced serious storm-surge consequences before. If you are evaluating a property on the Narragansett Bay or Mount Hope Bay side, or on one of the bay islands, expect the same CRMC review process to apply, even though the specific state figures cited above concentrate on the Sakonnet River side and the named vulnerable roads.

Either way, this page is not a substitute for direct professional guidance. Contact Rhode Island's Coastal Resources Management Council (CRMC) for current, parcel-specific permitting requirements, and consult a licensed marine contractor for current, site-specific guidance on whether a seawall, bulkhead, or revetment is even the right approach for a given Portsmouth property. Nothing on this page is engineering, permitting, or legal advice.