Where practical, the deck of the ford should follow the natural bed elevation.
If a concrete surface is used, then consideration should be given to the need for artificial roughness to be placed on the road surface, at least along the lowest section of the crossing. Such roughness may be achieved with the use of grouted rocks (instead of the concrete pad).
Exposed-aggregate concrete finishing should not be used as its
preparation can significantly pollute the stream's waters.
Minimise the use of causeways where fish passage is required.
Where practical, construct the deck to follow the stream's natural cross section to achieve variable flow depths over the causeway.
Install low-flow pipes/boxes to carry the normal dry- weather flow satisfying those conditions specified above for a "low-flow” culvert design.
REHABILITATING EXISTING CROSSINGS
Existing barriers should be programmed for replacement or appropriate rehabilitation. This may include modifications to the approach channels to reduce erosion and increase low-flow water depths, or the incorporation of baffles or added bed and side-wall roughness.
All reasonable and practicable measures should be taken to prevent or minimise environmental harm during the construction phase, including: minimising restrictions of fish passage; minimising the release of sediment into the stream; minimising damage to, or the removal of, bank vegetation, particularly vegetation that shades the low-flow channel.
Where practical, construction works across the bed of a waterway should be staged to minimise the total disturbance at any given time and to allow the full bypassing of stream flows around the works to maintain fish passage.
© Catchments & Creeks Pty Ltd
fish passage requirements for waterways crossings