There's a very exciting project that was finished at Scottsdale this week! Nearly four years in the planning, design and funding the Gungoandra Creek rock weir and fish way has been successfully constructed over the last three weeks.
It's the most significant component of the erosion control plan that volunteer soil consultant Peter Fogarty has helped Scottsdale with.
Funded by Actions for Clean Water (ACWA) through the Local Land Services with the help of Matt de Jongh, construction was ably undertaken by Brad Davies of NSW Soil Conservation Service and Jeff Kent of excavator prowess extraordinaire.
Its purpose is to halt the migration of an active head cut up through the creek into several kilometres of creek wetland. Controlling this head reduces the current high release rates of sediment from the creek into the Murrumbidgee River, significantly improves water quality and protects the valuable habitat of a wide range of frogs, mountain galaxia and many, many water bugs!
The construction of the weir entailed the installation of a large rock wall, cut into both banks and held in place by vertical steel columns that have been drilled into the bedrock.
Geofabric, some impregnated with bentonite, has been used to help contain the surrounding soil and to some degree to waterproof the main structure.
A fish way or ladder, carefully constructed on the original stream course, is a series of steps where the water drops 10cm for every 80cm of horizontal flow, this allows resting pools for the galaxia between their ‘bursts’ to climb the 10cm. In times of flood the main flow will overflow the wall itself.