The Nihotupu auxiliary dam is listed as a historic site in Henderson Valley, in the Waitākere Ranges of west Auckland. It has a 4.2 rating on Google. The Nihotupu dams are part of the water supply system that serves Auckland.
A good historic site helps you understand a place through what remains on the ground, often with signs to give context. A dam in the ranges is usually reached by a road or a bush track, and views across the water and the forest are part of the appeal. Because this is a water catchment and kauri forest, rules are strict: clean your shoes at any hygiene stations, stay on marked tracks, keep dogs out where banned and check Auckland Council or Watercare for closures before you go. Regulars know that mornings are quietest, that tracks are slippery after rain and that mobile coverage can be patchy. Bring water and a rain jacket, and take all rubbish home.
For anyone exploring Henderson Valley and the Waitākere Ranges, the Nihotupu auxiliary dam is a reminder of how Auckland's water supply began, and worth checking access before you visit.