Indicators of Catchment Condition in the Intensive Land Use Zone of Australia – Pesticide hazard

It should be noted that this data is now somwhat dated!

Pesticide (incl. herbicides, insecticides, fungicides and fumigants) use is a direct measure of the input of toxins into the natural environment and is relevant at property, catchment and regional scales. Pesticide use can be managed at the catchment scale through policies and/or regulations controlling applications, availability, etc.

Waterway health is sensitive to the magnitude, frequency and toxicity of applications. The NLWR National Land-Use map (2001) is currently the best available national coverage (1:1M). national pesticide use data set is not available.

Every land-use class in the NLWR land-use map was given a pesticide rating, based on the toxicity of pesticides used, frequency of application and $ spent. Rating is based on expert opinion (J. Walcott, BRS, pers. comm.), and assumes that each land-use can be equated to particular pesticide usage patterns. standard methodology has not been used.

Data reliability is poor, due to the subjectivity of the rating system, the lack of actual pesticide data and spatial integrity of the land-use map. The rating of pesticide use is unequivocal a a high rating, reflecting substantial and frequent application and/or high toxicity, implies a high waterway contamination hazard. However, the pesticide type, the method of application and usage has been assumed based on land-use practice, and is not an absolute measure of pesticide use. The indicator has not been validated, however it is widely understood by users.

Nature conservation and grazing on native pastures indicate a low hazard from pesticide. In contrast the areas of extensive cropping and the irrigation districts areas show a high application rate, with a consequent high hazard to land and waterway condition. The high hazard areas are concentrated in the 800-1000mm rainfall belt west of the dividing range in SE Victoria and NSW, and also parts in SW Western Australia, and in Central Queensland. The detailed analysis also suggests that many AWRC basins contain a wide range of hazard values.

The environmental linkage of pesticide hazard between sub-catchments is likely to be complex so area-based averaging of a hazard rating in AWRC basins may be misleading. River basins with relatively high hazard ratings include: Greenough, Avon and Blackwood Rivers in WA; Broughton, Wakefield, Gawler and Torrens Rivers in SA; Wimmera a Avon, Avoca, Yarra, Maribyrnong, and Latrobe Rivers, Tambo Rivers in Vic; in Tasmania, the Arthur and Rubicon Rivers; in NSW, the Sydney-Georges, Macquarie-Tuggerah Lakes, and Gwydir Rivers; and in Queensland, the Tully, Boyne, Calliope, Ross, Curtis Island, Maroochy, Johnston, South Coast and Mulgrave-Russell Rivers.

Data are available as:

• continental maps at 5km (0.05 deg) cell resolution for the ILZ;
• spatial averages over CRES defined catchments (CRES, 2000) in the ILZ;
• spatial averages over the AWRC river basins in the ILZ.

See further metadata for more detail.