It isn't really five hundred steps — nobody has counted properly, and the family has stopped correcting the children who insist on the number every single time. But it is roughly an hour down and an hour back, with a flask of something warm, along the same path the children have been taking for years: past the tea bushes, along the lower terrace, down to where the white stones show themselves every dry season and disappear again with the first heavy rain.
The dam itself is modest — a low wall of stone and concrete holding back water that becomes, further down the valley, somebody else's irrigation. You can't see the whole of it from the path; the best view is from the far ridge, a detour most guests don't bother making on a first visit and almost always regret not making by their second. What you can see from the path is enough: still water, the occasional heron standing in it like it owns the place, and the particular quiet that comes from being somewhere with no road nearby.
We'd suggest going down in the early morning, before the mist has properly lifted, or in the last hour before dark, when the light comes in low and gold across the water. Either way, take the flask. The walk back up is slower than the walk down, and it's a nicer place to stop for ten minutes than most.