The Waiuku River, also known as the Waiuku Estuary, is an estuarial arm of the Manukau Harbour, near the town of Waiuku, south-west of Auckland. It joins the harbour at the south west and extends south for , having its head close to the town of Waiuku. What is now Waiuku Stream, a tributary rising about west of Waiuku, was once shown on maps as Waiuku River.
Portage and proposed canal
Te Pai o Kaiwaka, also known as the Awaroa or Waiuku portage, connected the Manukau Harbour to the Waikato River in the south, via the Waiuku and Awaroa Rivers. A canal linking Manukau and the Waikato River was being considered as early as 1866. In 1921 a Royal Commission reported against a £475,000, canal, with the then predicted use. It would have included a cutting up to deep and a long bank at the Needles, with a x x barge lock in it and a road across the top. The canal continued to be mooted as an idea, and in 1924 the Waiuku Canal League was formed to promote it. It was again considered in 1965.
Vegetation
Mangrove cover in the Waiuku and Taihiki estuaries increased from in 1976 to 274 in 2006.
Gallery
<gallery>
Waiuku (ca 1911).jpg|Buildings along the edge of the Waiuku River (circa 1911)
Waiuku Estuary.jpg|The Waiuku River at low tide in 2000
</gallery>