At various stages of its life, there was talk of connecting the Manukau to the other waterways in the harbour's vicinity, the Waitemata Harbour and the Waikato River. The connection with the Waikato would have seen a canal constructed starting at Waiuku, and going through to Aka Aka, allowing barge traffic to and from as far south as Cambridge, some ninety miles from the Waikato river mouth. Two connections between the Waitemata and Manukau were considered. A Government Commission in 1920 recommended the construction of a barge canal, joining the Tamaki Estuary with the north-eastern arm of the Manukau, near Otahuhu, a half-mile away. The land concerned has been retained by successive harbour boards, and in 1989, was on five-year lease arrangements. As part of these plans, it would be necessary to build a lock at the Onehunga end to handle the three-hour, six feet tidal difference. The other connection point was via the Whau River, around the back of McLeod, Ken Maunder and Olympic Parks, utilising the Avondale Stream to emerge somewhere in the vicinity of Green Bay - a distance of 1.5 miles. The Waitemata - Manukau Canal Scheme was catered for in the 1908 Auckland and Manukau Canal Act, an Act which was repealed in 2010. The subject itself is superbly summarised in Sir Bob Harvey's splendid 2019 Waitemata Harbour-focused tome "Sea Edge".