One of the Wikipedia articles I am proud of is the Dutch article about the Oostvaardersplassen. The Oostvaardersplassen are close to where I live and I think it is one of the best examples that nature is something that not only evolves, but also can be engineered. I have followed its development with considerable interest and my favourite point of view has been that the water management has been detrimental to the natural diversity.
I visited the Oostvaardersplassen this weekend, and I learned that a small dyke will be removed leading to a more natural distribution of water and a more dynamic water level. This will have a huge impact on the fish stock; the current population of mainly mature carps will make room for many more smaller fish. This will allow many small herons and other fish eaters finding their niche.
The one remaining question for me is if fish will be able to freely migrate in and out of the nature reserve. It would be grand if this is the case.. As only one dyke is mentioned, I do expect it to be great but not "perfect".