In a battle of rival aerial images, the Friends of Minnamurra River (FOMR) are concerned about Boral’s 5B sand mine south of Dunmore House, and the dieback of the grey estuary mangroves. Boral claims the dieback started before the mining began.

Locals first noticed the dieback near the mine site in early March 2024, as shown in FOMR’s drone photos. Sand mining began on the site on 30 October 2023.

Mangrove dieback from water course (Credit FOMR)

FOMR spokesperson Will Chyra says the sand mine may have changed drainage patterns, which caused the mangroves to wither and die.

“Mangrove dieback has a number of common causes such as human intervention to local groundwater and drainage patterns, dredging for industrial purposes or housing developments and physical disturbance from clearing riparian vegetation,” Will Chyra says.

“The estuary dieback areas also appear to extend from the larger area near the shore, along both sides of tidal channels fringed with dead and dying mangroves, to a number of smaller dieback areas closer to the main river,” he says.

In mid-February 2024, Boral cleared all vegetation around the 5B dredging site, including a 400-year-old Bangalay sand forest and the rare Southeast Littoral Rainforest.

A Boral spokesperson says the images it supplied, taken in June and July 2022, show the start of environmental degradation - “a grey area”- before the construction of the 5B site.

Aerial images supplied by Boral, June & July 2022 (Credit Nearmap).

“Boral notes that aerial images of the small area of mangrove referred to by FOMR show progressively reducing mangrove vitality before the establishment of the Stage 5B pond … and is not likely to be the result of Boral activities,” a Boral spokesperson says.

“An alternative explanation could be that the mangrove dieback was due to changes in sea and water levels.”

Yet, an enlarged Google Map dated July 2022, shows little observable damage to the mangroves south of Dunmore House.

Boral sand mine 5B on left and mangroves to the right, July 2022 (Credit: Google Maps)

FOMR has asked the Department of Planning and Environment, and the Environmental Protection Authority (EPA) to investigate.

Mangroves take carbon dioxide from the atmosphere and bury it in their roots for thousands of years, which is released when they die.

The NSW Department of Primary Industries imposes a maximum penalty of $220,000 for a corporation, or $110,000 for an individual, found to have damaged a mangrove without a permit.

The dredge pit area will be left as a private lake at a depth of 27 metres, and will cover 7.5 hectares (18.5 acres), when Boral exhausts the sand supply in about 12 months.

The Dunmore Lakes Sand Mine project was approved by the New South Wales Independent Planning Commission in November 2020.