Dredged canals create indirect factors causing wetland loss. These factors include longer intervals of both wetland soil waterlogging and drying, sulfide toxicity, less organic matter and sediment accumulation, and greater shoreline erosion. There is a robust dose-response relationship between coastal land loss and canal density in the Mississippi and Niger river deltas over 5 decades. Importantly, the ratio of land loss:canal area increases with time – a legacy effect. Neither subsidence nor flood protection levees on the main river channel significantly magnify the effect of dredging on wetland loss. These consequences are contrary to a hypothesis that regional river channel flood protection levees or fluid withdrawal is of greater importance than the local changes in wetland hydrology. The cumulative effect of these direct and indirect dredging consequences in coastal Louisiana is enormous and continuing, equaling many tens of billions of dollars annually. Wetland restoration/mitigation of dredging impacts has been tried successfully but sparsely. Restoration of dredged wetlands can be implemented at a relatively low cost (less than 1/10th the cost per acre of alternatives) and quickly if this paradigm of the causes of coastal wetland losses is adopted.