Sediment analysis from Waikouaiti River shows normal levels of lead

The Otago Regional Council (ORC) today received results of riverbed sediment samples taken upstream and downstream of the water intake for the Waikouaiti raw water reservoir. The results indicate only background, ambient concentrations, and not elevated levels of lead.

The two results for lead showed 5.3 mg/kg upstream of the intake and 4.9 mg/kg downstream. The difference between the sites is not likely to be significant. These results are significantly below the Australia and New Zealand Government default guideline value for heavy metals in sediment, of 50 mg/kg for lead.

ORC General Manager Regulatory Richard Saunders said the sediment results were good news.

“These results suggest that the Waikouaiti River is in generally good health with regards to concentrations of lead. Any new information that helps us rule out lead contamination from the river is a step towards certainty for the affected communities.

“However, at this time we are not ruling out the possibility of a source of lead contamination in the river until more data has been collected. The DCC is sampling more widely in the catchment with input and assistance from ORC, and we look forward to learning more from these tests,” Mr Saunders said.