Didymo confirmed in upper Rangitata River and Rakaia River

The invasive alga didymo has been detected at two sites upstream of the Rangitata Diversion Race (RDR) intake on the Rangitata River.

The river was sampled after live didymo was confirmed in the RDR last week. The RDR runs between the Rangitata and Rakaia Rivers.

Samples were taken just above the RDR intake, in the Rangitata Gorge, and at Coal Creek. The RDR intake and Rangitata Gorge samples tested positive for didymo. The Coal Creek sample was negative.

Samples were also taken from the Rakaia and Ashburton Rivers at their respective State Highway One bridges. The Rakaia sample tested positive for didymo, while the Ashburton River sample tested negative.