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Mark Jekabsons: Cotter River

Mark Jekabsons: Cotter River

Bottle number: 2

About the water

A colour photo of Mark Jekabsons holding his water sample at his Cotter River collection site.
Mark Jekabsons

Collected at: Cotter River, Namadgi National Park, ACT

Approximately 1km upstream of Vanity's Crossing, Australian Capital Territory.

E: 671159m, S: 6086359m

View location on Google map

Collected by: Mark Jekabsons
Research and Planning, ACT Parks, Conservation and Lands,
Territory and Municipal Services

In October 2007 I was involved in a project radio-tracking several species to look at their response to environmental flow releases from Bendora Dam. I first trekked into this site while tracking a particularly troublesome platypus that holed up here for several days.

Water quality:

Turbidity: <10NTU
pH: 7.8
Nitrates: 0
Conductivity: 40┬ÁS
Phosphates: 0.01mg/l
Dissolved oxygen: 7mg/l

ACT Waterwatch says:

Beautifully clean water, at a beautiful site.

Cotter River, approximately 1km upstream of Vanity's Crossing, Namadji National Park, ACT
Cotter River, approximately 1km upstream of Vanity's Crossing, Namadji National Park, ACT. Photo: Mark Jekabsons.

About the site

This site on the Cotter River is within Namadgi National Park just before it flows into an area used for forestry. Here the river flows through a steep gorge and is lined by native vegetation. The stream bed is cobble and boulder. This area was significantly affected by bushfire in 2003 which introduced large amounts of sediment to the river, reducing habitat for threatened fish species and other aquatic life.

What's going on:

Vegetation around this site and over a large area was virtually wiped out by the 2003 bushfire which hit Canberra. Natural regeneration has been taking place in Namadgi National Park while the forestry area has been replanted. Large amounts of fine sediment which entered the river from the ash and exposed soil still cover the river bed, filling in many of the spaces between rocks that are home to aquatic life. This habitat may take years to be scoured clean.

In 2001 a fishway was installed downstream of this site at Vanity's Crossing which had until then restricted movement and breeding of the endangered Macquarie Perch. This site is now one of several that are looked at to determine if the fishway is successful and if breeding is occurring upstream by using snorkelling to detect tiny juvenile Macquarie Perch.