The Whangarei District Council is to investigate the cost of an upper harbour weir and lock.
The council was planning to build a second, no-frills harbour bridge to ease traffic congestion, with a government subsidy of 50%.
But a group of tourist operators, engineers and architects is urging it to go further, and build a weir at the bridge to keep water levels constant in the Town Basin.
A spokesperson, Jeroen Jongjens, says that that would transform the harbour and create many options for recreation and tourism.
The council says relieving traffic jams is its priority for a bridge, but it will ask engineers to price the weir project, and then review its options.