1999-2000: Dirranbandi Weir (Qld). Pesticides: Multiple

Water quality in Queensland catchments and the cotton industry
Dave Waters Cotton CRC, Qld NRME, Toowoomba 2001

In 1999-2000 sampling, 29 sites across the region of NSW and Queensland were monitored for 34 agricultural chemicals. Endosulfan, atrazine, diuron, fluometuron, metolachlor and prometryn were detected. Atrazine was the most frequently detected herbicide, with the second most
frequently detected chemical being endosulfan.

The CBWC pesticide-monitoring program was conducted at the following town weirs – Millmerran,
Cecil Plains, Dalby, Chinchilla, Surat, St George and Dirranbandi in the Condamine Balonne River system. This work was continued in the later years through funding provided by the chemical company Syngenta. Cotton is grown upstream of all sampling locations and would therefore
have the potential to contribute to contamination of the water bodies sampled.

Water samples were analysed for 52 pesticides. These chemicals included the alpha and beta isomers of endosulfan, as well as endosulfan sulfate and the breakdown products of atrazine – desethyl atrazine and hydroxy atrazine. Eight chemicals were detected in all five weirs:
metolachlor, dieldrin, simazine, atrazine, atrazine desethyl, atrazine desisopropyl, prometryn. A byproduct of DDT (p,p-DDE) was detected on one occasion.