The issue

Black Bobs Creek, a tributary of Wingecarribee River, is typical of many upland streams in degraded areas of the catchment. The bed and banks of the creek have been eroded, making the channel deeper and wider. With every flood, water travels through the system much faster than in a natural system and causes more erosion.

The lower creek bed has led to the creek and floodplain becoming disconnected. Floods are unlikely to overtop the banks and deposit sediments and nutrients on the floodplain which naturally replenishes the landscape.

In addition, four crossings on the lower section of the creek did not allow fish passage on the creek, one of these crossings was identified by the Department of Primary Industries' "Bring Back the Fish" report as a medium priority crossing for modification.

The strategy

The Catchment Protection Scheme - a partnership between the Hawkesbury-Nepean CMA and Sydney Catchment Authority -- provided $175,000 for a project to restore 5 kilometres of Black Bobs Creek near the confluence with Wingecarribee River. The project worked with one property manager across 4 properties.

The broad aims of the project were to stabilise the creek bed and banks, raise the bed level and improve water quality by trapping sediment. To do this the project:

• raised the bed of the creek by installing 7 rock ramps (each with a fish way) to capture and store sediments
• protected banks and installed log structures at key points (as well as mesh fencing on banks)
• raised the ground water table by lifting the bed of the creek reduced the energy of water flows and lessened erosion potential
• recreated fish habitat and pools/riffles in the system

HNCMA perspective

The CMA's Brad Davies managed the project. "This was an important site for the HNCMA to work on in terms of both soil protection and the potential to restore fish habitat." "We've already seen native fish moving through the fish ways in low flows. They include agile swimmers such as Mountain Galaxias, Flathead Gudgeons, eels and Smelt.

The Wingecarribee River catchment is also a known habitat for Macquarie Perch and there is the potential for these vulnerable native species to move into the rehabilitated reach in the future," said Brad.

The results

By mid-2007 the project had: