Hi! Thanks for letting me know. I checked, and most of these reservoirs probably don't exist. I already deleted a bunch of them before and I simply retagged the rest, including this one. I just fixed this case and a few others here: https://www.openstreetmap.org/changeset/137631347

Feel free to remove data in this area that you can't verify, because there is a lot that is either outdated or outright wrong.