Bunya Crossing Fish Friendly Scour Protection Project 2020

Bunya Crossing is located on the South Pine River, Eatons Hill, 15 km north northwest of Brisbane, Queensland. It is a multi-culvert pedestrian crossing that allows bush walking access to both sides of the River within Sargent Reserve. Moreton Bay Regional Council were looking to improve both fish passage and scouring issues at the crossing. This was achieved by designing and installing fish-friendly scour protection that was compliant with Waterway Barrier Works Acceptable Development conditions, avoiding the need for a Development Approval.

The crossing had a 300 mm drop off of the downstream apron caused by scour, which created a barrier to fish passage during both low and moderate flows. This drop was rectified by constructing a rock ramp from different sized rocks that were all locked together to prevent scour. The ramp was designed so that there was no longer a drop from the culvert apron to the downstream water level, that water velocities through the culverts reduced, and that flows were broken up by large rocks that stand proud of the water to facilitate fish passage.

On the second day of construction, upon completion of the low flow channel only, fish passage was partially restored, and fish as small as 20 mm were filmed using the half-constructed ramp! Post-construction monitoring by Moreton Bay Regional Council showed that fish abundances increased by 40% as a result of the remediation.