Mobile Bay, AL · $95B (proposal)
MOB-13 · Mobile Bay Estuary Tidal Sluice
Interlocking mechanical steel gates spanning the entrance to Mobile Bay, designed to seal the estuary off from Gulf hurricane surges while letting normal tides and shipping pass during calm weather.
Pros
- A single chokepoint protects the entire bay — efficient geometry for the investment.
- Mechanical gate systems are well-understood; no exotic materials or unproven physics.
- Shields Mobile's port and the inland waterway system that feeds the Southeast.
Cons
- Sourcing 1.2 million tons of specialty steel on a fast timeline collides with every other project on this list wanting steel too.
- The "melt down decommissioned tanks" fix is colorful but not a real supply chain.
- Sealing the bay mouth disrupts the estuary's flushing; Mobile Bay's famous seafood industry depends on that exchange.
Feasibility: Straightforward as these things go — a smaller cousin of the Thames Barrier concept applied to a bay mouth. The engineering is conventional; the challenges are procurement and ecology. Of all the Gulf gate projects, this is the one most likely to survive contact with a real budget.
Aerial mock-up: A continuous line of interlocking steel gates spanning the bay entrance like a rigid bridge, isolating the inner estuary from Gulf hurricane waters.
