It could have drowned from breeding, it can happen on accident. Or an egg issue. They can die suddenly with little sign. Sometimes new layers can have some issues and show no signs. Going in the water can help them lay eggs. But something else could of happened too. It is really hard to tell for sure.I did
I did read about a bacteria/parasite, but I figure there would have been an ill period where it's apparent no? She was neck extended and feet behind like some people noted in threads.

I can't wait for them to moult all those ratty feathers out...