A dam in a high valley cut.
What do you do with a mountain near your settlement - build something! When I saw the small valley I knew immediately that a dam belongs here (was one of my first projects in Minecraft).
Instructions:
You just have to build a slightly inward (towards the reservoir) curved wall of some material. It should also be noted that the bottom of the dam should be slightly inclined towards the valley.Whether you add a waterfall for effect like I do is a matter of personal taste.
For touristic reasons I added an inn in the background later.
The dam as seen from the settlement (and yes, you can guess where I'm coming from :D. I did not want to dismantle the lettering for the screenshot)

The reservoir is half frozen.

The dam wall is slightly curved backwards and the dam bottom is slightly inclined towards the valley.
The glowstone lighting behind the waterfall is only for optics at night.

Since many people choose the dam as an excursion destination, an inn has been built here, which offers a breathtaking view of a hidden valley on the back side.


I rate with neutral. The dam itself looks now not sooo spectacular, cool that you have paid attention to the slopes, but the sandstone with the simple quarry stone wall on top is now really no eye candy.
But I find your landscaping beautiful, so how you have inserted the buildings and also the lake in the existing landscape. The environment seems "round" and alive.
But since this is not the topic here, but the dam, so it falls heavier into the weight and it becomes only neutral.
You might also want to try giving the dam a pattern with chiseled or polished sandstones. And work in the places where the wall pushes forward with stairs, that makes everything look a little less rounded.
the idea is not new but I like the design
Thank you for your comments. As described, the dam was one of my first builds and thus a bit "clunky" and lacking in detail.
I immediately started to improve it, especially the quarry stone wall is really "suboptimal".

In addition, I have set in the wall sandstone steps to reduce the "clunky" something. About the pattern I'm not happy yet, I still need a bright idea.
In one of the first worlds I ever built, I also have a sandstone wall that I decorated with ornaments so it doesn't look so barren.

Maybe this will be an inspiration to you:
But as I said, it's one of my very first worlds and not particularly imaginative either.
I build walls mostly in this style, but how it can be useful for you I don't know:
And now here is my interpretation of a dam, the outlets can be controlled individually.
Is the Reforged Texture Pack.
Even now I find the metal fence on your embankment rather suboptimal, you should use something that doesn't stand out so much, so maybe a wooden fence or you build a railing of sandstone steps + stairs, something like this:
I have now built extra for illustration 😀 but can of course omit the stairs and take only stones and steps.
But if you like it the way it is, keep it that way. You decide for yourself how it looks in your worlds.
Well.so.the.idea is already there. However, also an alternative where you can still build it. I.would build the dam either from stone Steinzeitegeln or wood but well give neutral therefore the idea is not new and the design is not really ingenious and positive I find actually only that you have built it on a mountain I have also already built a few but with lock and on a mountain that ends at the river or sea.