As I understand it, the Netherlands pays for this maintenance themselves, and not from EU funding? If it were relying on EU funds then I'd expect some kind of European benefit analysis would be required.
We have a seperate branch of government called Water Boards[0]. They are some of the oldest forms of government in the world dating back to 1255.[1]
The water boards raise their own taxes, and we elect officials for it in separate elections.
Basically we don't want regular politicians to make budget trade offs between long term safety and short term <whatever they campaign for>. I'm sure we're all familiar with long term planning capabilities of regular politicians.
To answer your question: yes. We do fund this our selves. I was saying I'm glad we do it this way in stead of begging the EU for funds.
The Sewerage and Water Board in Orleans Parish is autonomous and exempt from certain civil service rules for much the same reason (although the Mayor appoints the director and can chair meetings). This is not to be confused with the Orleans Parish Levee District, which rightly or wrongly was perceived as having its fingers in too many pots after Katrina so had many of its responsibilities taken over by regional agencies controlled by state government (SLFPA-E and W)
1/3 of our country is below sea-level or around 0m NAP. Levees and flood protection are like fashion or politics: they're never finished, not really.
I'm glad we do this out ourselves in stead of the EU deciding whether they want to subsidies a bunch of people living in a delta.