Oolloo Aquifer Groundwater Test Results

A study by the Department of Environment and Natural Resources (DENR) aquatic health unit has found low concentrations of pesticides and nitrate (a plant nutrient) in Oolloo aquifer groundwater in the Douglas Daly and Katherine areas.

The Oolloo aquifer is the uppermost formation of the Daly groundwater basin and overlies the Jinduckin formation and Tindall Limestone Aquifer.

Groundwater from the Oolloo aquifer provides the majority of dry season flow for the Daly River.

DENR Senior Scientist Julia Schult authored the Pesticides and nutrients in the Oolloo Aquifer report and said the findings were generally quite positive.

The study tested 25 bores in the Douglas/Daly and Katherine regions as part of a rolling program of baseline pesticide and nutrient monitoring of groundwater of the four Top End water allocation plan areas and aimed to:

· Investigate whether there are any pesticide residues in Oolloo aquifer groundwater.

· Determine the levels and extent of plant nutrient concentrations, in particular nitrate.

· Provide a baseline for future studies of groundwater in the region.

“Nine different pesticides, mainly herbicides, were detected with the herbicide atrazine being the most common contaminant found in 15 of the 25 bores tested,” Ms Schult said.

“All pesticide concentrations were below drinking water and/or ecological guideline values, where such values are available.

“The nitrate concentrations we detected are quite low compared to other parts of Australia, and the world.

“Nitrate concentrations were elevated under agricultural land, indicating that such land uses, likely involving fertiliser application, are having an impact on Oolloo aquifer groundwater.

“The report serves as a reminder to use best practice for storage and application of all agricultural chemicals and fertilisers.

“Globally, nitrate is the most common groundwater contaminant.”

Go to https://denr.nt.gov.au/land-resource-management/water/water-publications/water-publications to download a copy of the Pesticides and nutrients in the Oolloo Aquifer report.

To learn more about water resource management in the Northern Territory, go to https://denr.nt.gov.au/land-resource-management/water

Last updated: 25 July 2018