Savannah, GA · $65B (proposal)
SAV-8 · Savannah River Tidal Isolation Sluice
Heavy vertical lift gates across the mouth of the Savannah River that drop to block storm-driven saltwater from pushing upstream — protecting the port, the city, and the agricultural freshwater intakes that depend on the river staying fresh.
Pros
- Cheapest project on the Atlantic list, with a tightly scoped single-river mission.
- Vertical lift gates are proven tech — the same principle as canal locks worldwide.
- Protects both urban infrastructure and upstream agriculture in one structure.
Cons
- The Savannah is a working river; gate closures during storm season would idle the port repeatedly.
- 800,000 tons of steel in a brackish estuary means relentless corrosion maintenance forever.
- Blocking the river mouth during peak flow risks upstream flooding — the cure could flood Savannah itself.
Feasibility: The most buildable project on this list. River-mouth sluices exist worldwide at smaller scale, and the engineering is conventional. The real questions are operational — how often the gates close, who decides, and whether the port economy tolerates it. A genuine candidate for a pilot.
Aerial mock-up: Massive steel towers flanking the riverbanks, suspending thick vertical gates that lower to block saltwater intrusion during Atlantic storm swells.
