2013 December – 2014 March: Picnic Crossing (Lake Tinaroo) Qld. Pesticides: Multiple

“A total of 14 pesticide residues, 3 herbicide degradation products, 2 synthetic musks and 1 flame retardant were detected in the passive samplers and grab samples in the Upper Barron River between December 2013 and March 2014. The sampling captured low flow (mid-December to mid- January), high flow (mid-January to mid-February) and moderate flow (mid-February to mid-March) events. The residues detected included the herbicides ametryn, atrazine, diuron, hexazinone, metolachlor, metsulfuron methyl, pendimethalin, picloram, prometryn, simazine and tebuthiuron and the herbicide degradation products, 3,4-dichloroanaline (diuron metabolite), desethyl atrazine and desisopropyl atrazine (atrazine metabolites). The insecticides detected included chlorpyrifos, diazinon and imidacloprid and the synthetic musks detected were galaxolide and tonalide. Tris (2- chloro-1-methylethyl) phosphate (TCIPP) was the only detected flame retardant in the samples. Ouranalysis suggests that none of these chemicals were detected at concentrations known to cause environmental harm, although diazinon and chlorpyrifos exceeded 99% ecological protection trigger values during each of the three monthly monitoring periods undertaken. However, the 95% trigger values were not exceeded and are more appropriate to apply given this would be considered amoderately disturbed site. Overall, compared to other regions of the GBR, the pesticides (and other chemicals) in the Upper Barron Catchment that drain into Tinaroo Dam, are considered low risk.”

Source: Barron River pesticide monitoring and Cairns WWTP WQ assessment.

Dominique O’Brien, Stephen Lewis, Christie Gallen, Jake O’Brien, Kristie Thompson, Geoff Eaglesham, Jochen Mueller Report No. 14/40 June 2014