I’d say its only the first one.
The other 3 are all general anti-doing-stuff arguments, and dredging, on net, is better on all those metrics than the alternative of not-dredging and continuing the status quo.
That said, I personally have no idea what the balance of direct environmental damage is between different amounts and methods of dredging.
I expect that when environmentalists attack dredging, it’ll be, in rough order, for the following claimed reasons:
Dredging directly destroys habitat and animals
Dredging burns fossil fuels
Dredging makes it easier to mitigate the effects of climate change, making coastal regions feel less pressure to avert climate change
Dredging speeds up the economy, which is bad for the environment
I am planning on a report to examine the first three issues. But there is always the degrowth perspective to contend with as well.
I’d say its only the first one. The other 3 are all general anti-doing-stuff arguments, and dredging, on net, is better on all those metrics than the alternative of not-dredging and continuing the status quo. That said, I personally have no idea what the balance of direct environmental damage is between different amounts and methods of dredging.