GOULBURN RIVER IMPROVEMENTS

After the great success of the first boulder fields, upstream on the corner behind our property and upstream from MC Martin’s Lane, the Catchment Management Authority have installed two new boulder fields.

Extending downstream from the first field on the corner, boulders have been planted in arandom pattern up to half way across the river. The field is about 80 metres long and made up of large and small granite boulders. Each one provides hydraulic features in otherwise flat, fast water. Each boulder accelerates and slows the water, tearing u the gravel and loosening the cobble, making holes and gutters around each boulder.

In each complex set of currents there are neutral places where trout can sit without effort. On the surface the food is deflected into concentrated bubble lines that trail behind the boulder for many metres. On the front/leading upstream pillow of water that forms in front of each boulder, the trout find a hydraulic lift where they can surf the bulge of water that slows momentarily in front of the rock.

The second field is at Thornton beach and consists of about 25 boulders, big enough to hold in the current. They reach from the north bank across to the caravan park in the fast tail of the pool. Further downstream, just below Thornton Bridge is a new rock groyne, deflecting water flows away from the bank.

Willow clearing has been extensive below Thornton Bridge. This has opened up a wide expanse of gravel beds. The willows on the Thornton side have all been removed and piled
up. At the moment it all looks very bare and severe but it will soon recover as spring rains and warmth trigger extensive regrowth.

Make sure you have a look when next in the area.

Geoff Hall