Jennifer,
This is very interesting but it suggests that currently fresh water ecologists are damning up-stream regulation devices and dams as environmentally unsound, while at the same time supporting and advocating the necessity to fill what amounts to a dam of the river estuary. How can that be justified on scientific grounds?

Also, can you tell me what technical justification was used to change the operation of the barrages from two way flow - which they were built to provide - to the one way flow that we see today?

Regards
John