Kirk here with a followup to William's post about Isahaya Bay. William has already introduced the gist of the issue but I thought I'd share this English-language news article as well.
As William pointed out the estuary has been important to the health of the entire Ariake Sea. Fishers are angry about the damage to the environment that chopping off the mud flats did. In fact, the loss of the wetlands may be one factor in the decline in clams (asari) that we've reported about. It's hard to know exactly how much of the asari probably can be blamed on the damming of the estuary but it certainly didn't help.
Finally, here's a good web page on the history of the issue:
https://www.jawan.jp/e/news/081015isahaya2.html
https://www.asahi.com/ajw/articles/14582114
High court rules Isahaya Bay floodgates can remain closed | The Asahi Shimbun: Breaking News, Japan News and Analysis
FUKUOKA--Four years failed to dampen the Fukuoka High Court's view of a protracted legal battle in Nagasaki Prefecture between fishermen and farmers over reclaimed land in a once bountiful bay.