Toxicity of Djalkmara Billabong water to local aquatic organisms: Pre-release biological testing for the 2002-2003 Wet season

Department of the Environment and Heritage, 2003

Internal Report 422
Hogan A
Supervising Scientist Division

About the report

Djalkmara Billabong is a natural water body located on the Ranger Uranium Mine site. It plays an important role in mine water management as it is used as a reservoir for low-level contaminated water and natural run-off prior to release into Magela Creek. During the wet season each year, toxicity tests using local aquatic species are undertaken on billabong water due for release. The results of these tests allow for the calculation of safe dilution levels to ensure the protection of downstream ecosystems.

Tests protocols using the local species Moinodaphnia macleayi (Cladoceran), Hydraviridissima (green hydra) and Mogurnda mogurnda (purple spotted gudgeon), were developed at eriss for this purpose, and have been used in recent years to assess release water toxicity (Allison et al 1991, McBride et al 1991, Markich & Camilleri 1997). An embryo mortality test using Melanotaenia splendida inornata was developed and used routinely from 1996–1999 by Ranger environmental staff.

Safe dilution concentrations are calculated by taking the No-Observed-Effect-Concentration (NOEC) of the most sensitive species tested and dividing this by a safety factor of 10, as recommended in the ANZECC/ARMCANZ Water Quality Guidelines (2000).