Atchafalaya Basin, LA · $135B (proposal)
ATC-17 · Atchafalaya Basin Delta Land-Builder System
Eighty-five custom dredging arrays pump Mississippi River silt through hundreds of miles of pipeline, depositing it across 500,000 acres of marsh to grow a 10-mile-wide buffer of new land between the Gulf and everything inland.
Pros
- Works with the river instead of against it — this is how the delta built Louisiana in the first place.
- Louisiana's coastal master plan already does small-scale sediment diversions; the science is validated.
- New land is permanent protection that needs no power, no maintenance crews, no moving parts.
Cons
- 500,000 acres is roughly 40x what Louisiana's current diversions attempt — the scale jump is vertiginous.
- Rapid silt dumping can smother existing marshes and fisheries if the balance is wrong.
- 85 dredging arrays running 24/7 is an enormous diesel and labor footprint for a "green" project.
Feasibility: The most scientifically grounded project on the list. Louisiana's Mid-Barataria diversion — a real, funded project — proves the concept at $3B for a fraction of the scale. The question isn't whether it works, it's whether it can be scaled 40x without wrecking what it's trying to save. Start with 5x and learn.
Aerial mock-up: A chaotic web of sediment pipelines threading the marshland, the aerial view transforming over five years from open water to a dense green 10-mile buffer of new earth.
