that was a VERY enjoyable set you've created from Bavaria!! Such sophisticated beauty in the landscaping and architecture!
I take some pride - by osmosis - that we both have the same camera and lenses..lol. Hopefully your good photographic sense will transfer to me somehow!
(is it me or are there a few where the horizon is a little tilted? - small matter easily corrected if you think it matters)
As for your question: that's a tough one. I don't think the pol-filter is "the answer" even if it may help some. The issue, I'm guessing, is that you have metered for the forest/pavilion part of the image, but the wide band of water in the background is throwing light at you.
There are two things I would experiment with together:
1) Lens hood/using your hand
2) Composition: zoom in so that the foreground-water is not seen and re-meter.
Alternately you can try to meter for the water, get the forest/pavilion a little too dark and manipulate in post-processing.
Essentially, the challenge here is that there is a large area of the image emitting a LOT more light than the rest of the image. The camera has to apply some sort of "average" and there probably is no such "average" that will make two such radically different areas look good at the same time.
Seems like a "by the book" -challenge for HDRmaybe...
Thanks for sharing those great pics - although it sadly remindsme that it's been too long since I've been in Europe!