This was contained in an environmental quality report tabled in Parliament yesterday, which included recommendations for the ongoing protection and management of the sand plains.
It was prepared after the EPA found that unless something was done soon, there would be a high probability of a gradual decline and ultimate extinction of one of the most important areas of biodiversity in the Darwin region.
The threats are primarily caused by long-term extraction of sand and gravel, and adjacent expansion of urban and rural developments.
The Howard Sand Plains is the habitat for a nationally threatened plant species (Typhonium taylori) found nowhere else in the world, a threatened palm found nowhere else in the Northern Territory (Ptychosperma macarthurii), a threatened species of bladderwort (Utricularia dunstaniae), and a threatened species of frog, the Howard toadlet (Uperoleia daviesae) found nowhere else in the world.
The area consists of areas of fine sand along river flood plains surrounded by gravelly rises, and is an important site for the provision of minerals, sands and other construction materials.
While the EPA said mining for fine sand in the Darwin region removed around 41ha of native vegetation per year, this was expected to increase by 70% by the year 2020.
NT EPA chair Bill Freeland said the report was issued because mining in the sand plains had altered, and continued to alter, the extent and distribution of sand sheet heaths across the north-south and east-west extents of the flood plains, which affected the area’s biodiversity.
“Major threats to the sand plains’ biodiversity are rural land uses and development, abstraction of ground water, and habitat removal and hydrological impacts associated with mining,” he said.
“It is anticipated that without intervention sand mining will eliminate the Howard Sand Plains and its biodiversity within the next 15 years.
“The report highlights the absence of effective ways to restore biodiversity following impacts of sand mining and recommends adoption of a protected area to preserve the biodiversity of the sand plains.”
The rapid increase in mining of extractives was associated with recent demand from urban expansion and development, along with the INPEX gas plant and other developments on Darwin Harbour.
Lands subject to mining disturbance cover 4.1% of area of seasonally saturated or inundated soils of the Howard Sand Plains.
The potential threats from mining are not independent of each other, with interactions between the water table lowering effects of enhanced evaporation from pits and the raising of a water table by early wet season rains proving difficult to measure and assess.
Mining operations in the vicinity include Primary Gold’s Toms Gully project, Compass Resources’ Browns sulphide project and the Ranger uranium mine at Jabiru.
