Once described as the food bowl of Te Arawa, the health of the Maketū Estuary has been in decline since drainage work was carried out in the 1950s.
But after completing a project to redirect the Kaituna River 12 months ago, the Bay of Plenty Regional Council says the estuary is already showing signs of improvement.
"The gates have finally been opened under the consent obtained for the diversion of the Kaituna River," Stephen Park, senior environmental scientist at the Bay of Plenty Regional Council said.
"It's now flowing around 600 cubic meters per tidal cycle.
"For many years the river's not been flowing at all into the estuary and the estuary's been filling with sand from the bottom end, from the sea. The nutrients have not been exported out so it's been accumulating. Over time there's been a wide range of detrimental effects that have taken place in the estuary in terms of ecological impacts."