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Work planned to improve Thornton Lagoon

Thursday, 8 January 2015 10:00 a.m.

Works to install a culvert from the Rangitāiki River into Thornton Lagoon aim to benefit fish and improve water quality in the lagoon.

The culverts will provide a connection to allow fish to pass easily between the lagoon and the river. It will also allow for additional water exchange between the river and lagoon improving the overall water quality. With the new connection and increased water quality it is expected that fish life will flourish in the lagoon. A reed cordon will help contain any stray fragments of aquatic weed that might enter the lagoon via the culverts.

A karakia will be held on site on Monday, January 12 before construction starts on Tuesday, January 13. The causeway leading to the river mouth on the Eastern side of the Rangitāiki River will be closed for up to four days while the works are completed. There will be no public access to the causeway during this time.

The culvert project finally came about after the Rangitāiki River Forum requested action be taken to reconnect the Rangitāiki River to the Thornton Lagoon. The Bay of Plenty Regional Council Rivers and Drainage Section worked with local engineers and ecologists to investigate a green innovative design for the project.

A 10m-long 1200mm diameter concrete pipe under the causeway will provide the bulk of the water exchange, while a higher 600mm diameter pipe nearby will provide a free water surface for fish navigation at high tide leading into a series of pools, a fish passage pathway and a natural reed barrier.

The weed inspection zone would likely become a resting place for mullet and kahawai at low tide when swimming to the river is difficult.

Partial funding for the project has been granted by the Bay of Plenty Regional Council Environmental Enhancement Fund in conjunction with a local community group.

Thornton Lagoon