I need advice on building a dam

Any advice? I don't know what terrain would be good for building large dams other than draining ocean sections, which is very tedious. Plus I'm aiming more for an artificial lake.

I want it to be in an area where you don't have to do much terrain tweaking, where the lake will not freeze, and if possible, where it could form islands. I'm hoping for the length to be in hundreds of blocks.

Thanks for any advice. I plan to build some of these at my outpost, but have no idea where a good spot would be.

That's a very specific terrain that you're probably not going to find naturally. The best option I can think of is to terraform the land a bit, though it might be tedious.

Thank you.

I'd say find a hills or redwood forest, these generally have a higher y than surrounding biomes. This will allow you to get the water level drop to our flow with minimal effort.

What sort of dam are you building anyway? Clay / concrete (basic aesthetic assumed on type)

Thanks for your input. I plan for them to be realistic looking, mainly out of polished andesite.

Have you already chosen where you want to build it?

No. I am trying to get advice on what terrain would be best, I have nearly all the biomes in my very large outpost.