But a barrage would reduce the tidal currents, so a lot of that sediment would settle to the floor of the estuary, it wouldn’t get stirred up so much.
The water would be clearer, allowing more sunlight to reach deeper into the water,
which might lead to more food for birds and other animals, attracting new wildlife to the area.
So it’s a complicated environmental picture.
Have they tried this anywhere? Built a barrage?
Yes, there are several in operation. There is one in France.
Now, they have to be careful there about how they turn on the turbines because they create currents and waves that can affect boats.
But I haven’t read about any major ecological problems, in fact, the fishing is supposed to have improved.
Plus there is even more bird life, but some of the barrages we’re considering now would be much larger than that one.
There has been one proposed from the estuary of Great Britain’s Severn River, one of the largest estuaries in the world.
It would be 16 kilometers long. Just to give you an idea, the barrage in France is less than a kilometer.
Outside of environmental concerns, such a project would be hugely expensive and that’s another argument against barrages, well, such large ones anyway.
Critics say that it would better to use that money for something else, such as improving the energy efficiency of buildings.
You could make a lot of buildings more efficient with all that money and that would reduce the need for electricity.