Wonboyn Lake soil samples by OEH and Forestry Corp offer differing conclusions

Silted up: it was the unusual orange colour of the water, not the flood itself, that most concerned Wonboyn Lake residents during this big rain event last April, with a pink soil now under investigation. Picture: Caroline Henry
Silted up: it was the unusual orange colour of the water, not the flood itself, that most concerned Wonboyn Lake residents during this big rain event last April, with a pink soil now under investigation. Picture: Caroline Henry

Community concern over unusual siltation of Wonboyn estuary has intensified, with emerging reports that scientific studies conducted by the Office of Environment and Heritage (OEH) and NSW Forestry Corp present conflicting results.

As reported last week, a meeting was conducted at Wonboyn Lake on Wednesday, February 10, with the OEH, Forestry Corp, BVSC, and EPA presenting evidence to approximately 50 Wonboyn residents.

Of most concern was whether the incidence of the unusual orange coloured silt in the lake is linked to logging in the Wonboyn catchment, with soil tests focused on the occurrence of pink Ordovician Turbidite soil.

Wonboyn Lake Ratepayers Association president Andrew Jeeves alleges OEH’s soil sample results are “diametrically opposed” to results presented by an undisclosed scientist engaged by NSW Forestry Corp, creating a major “sticking point” in the investigation.

“OEH identified the soil as highly erodible, while Forestry Corp representative Lee Blessington said he believed it was one of the most stable soils he had worked in.”

Buoyed by positive investigation results thus far, Forestry Corp will continue logging in the Wonboyn catchment.

“The draft report issued by the Environment Protection Authority cites no evidence the sediment was a result of forestry activities,” a NSW Forestry Corp spokesman said on Tuesday February 23.

“Investigations by Forestry Corporation’s soil scientist found that there was substantial evidence of alternative sources of sediment within the catchment and outside of the state forests which had not been investigated by OEH.”

The Magnet sought clarification with the OEH, who issued a formal statement on Tuesday, February 23, focusing on the nature of the soil type found in the Wonboyn catchment, which dates back more than 400 million years.

“The soils formed during this period are predominantly clays that are reddish in colour and produce extremely fine grained sediments that when mixed with fresh water stay in suspension for a long time,” an OEH spokesperson said.

“The suspended sediments eroded from soils from Ordovician rocks are an inert clay and considered not hazardous.”

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