Tallowa Dam Fishlift - Shoalhaven River
Structures that will support guiderails and hopper transport mechanism under construction on the downstream side of the weir crest.
Dubbo Weir Rock Ramp Fishway - Macquarie River
Looking across natural rock ridges in the centre of the fishway. These ridges will act to slow water movement and provide fish passage from upstream (left) to downstream (right) of image.
Sydney Olympic Park Fishway - Boundary Creek
Levels of surrounding structures are checked to ensure the fishway will allow for upstream fish movement.
Bumbuggan Weir Fishway - Bumbuggan Creek
Fishway design needs to accommodate water management as well as fish passage.
Bumbuggan Weir Fishway - Bumbuggan Creek
Water control gates act to provide attraction flow to guide fish to the fishway entrance. The rate of flow and its location will influence a fishway's success.
Fishways are technical structures that aim to provide suitable water velocity, turbulence and depth conditions that allow fish to safely swim upstream and / or downstream of dams weirs and road crossing barriers. Prior to 1985, the predominant fishway design utilised in NSW was the submerged orifice fishway which was designed to pass northern hemisphere salmonoid species such as salmon and trout.
Unfortunately, Australian fish display reduced swimming capabilities compared to salmon and trout, meaning that the pre-1985 fishways were completely unsuitable to pass native fish species. Subsequent research has determined that technical fishways including Rock Ramp, Vertical Slot, Denil, and Lock fishways can effectively pass Australian native fish if suitably designed.
These fishway designs require technical specification to ensure that designs and standards are met and that water conditions in the fishway are adequate for the swimming performance and behaviour of target fish species and size classes.
NSW DPIRD Fisheries have developed documents that identify the recommended process in NSW to designing a technical fishway, ongoing operational and maintenance and procedures for assessment and monitoring. We are also working on developing appropriate fishway design standards. These recommendations are based upon the past 20 years of experience in designing and building effective fishways, with the aim to ensure adequate consultation and consideration of ecological priorities, hydrologic conditions, constructability considerations, and asset operational factors.
The recommended process in NSW to designing a technical fishway is outlined below.
Recommended fishway design process
Personnel
Critical to designing a cost-effective fishway is to have the appropriate personnel assisting in the design process. A list of recommended personnel to be involved in the design of technical fishways is shown below. Additional personnel may be required depending upon the complexities of the project, this should be assessed on a site-by-site basis.
- Asset owner (Manager) - oversees capital assets
- Asset owner (Operational Manager) - provides detail on how the weir structure is operated and maintained
- DPIRD Fisheries (Fisheries Manager, Fish Passage) - departmental / legislative representative ensuring fishway design meets fish passage policy and guidelines
- Fish passage consultant / ecologist - expert in fishway ecology including ecological modelling and hydrologic assessment
- Fish passage engineer consultant(s) - expert in fishway design and construction processes
- Funding organisation - as required
The following design stages are outlined to provide a template for how to progress through the assessment and design of technical fishways in NSW.
Project startup
- Establish an expert design team (experienced fishway engineers, fishway biologist, local water officer, asset owner including operations manager)
- Detail data requiring collation (e.g. ecological data, hydrologic gauge data, proposed operating strategy)
- Identify data gaps
- Set date for additional data collection and dissemination
- Set date for site inspection
Data gathering and assessment
- Collate ecological data (fish assemblages, abundance / rarity, distribution, status), and hydrological gauge data (headwater / tailwater, flow duration curves, exceedance data, flow event curves, e-flow arrangements)
- Develop concept ecological model
- Develop concept hydrologic model
- Develop operational requirements – infrastructure & ecological
- Disseminate information for assessment and review
Initial concept design workshop
- Inspect fishway site and surrounding catchment (e.g. note additional barriers, habitat features)
- Assess fishway design features on-site: entrance location, exit location, design and operational constraints, operational range, access arrangements for maintenance & monitoring
- Discuss and agree on ecological and hydrologic models
- Discuss and agree on ecological priorities
- Optimise tailwater level / headwater level ranges relative to site / operation constraints
- Validate fishway design options against ecological and hydrologic criteria
- Agree on concept design option(s)
Second concept design / initial detailed design workshop
- Discuss concept design(s) (review entrance, pools, gradient, hydraulics, hydraulic operational range, attraction flows, trash racks, weir operation, fish traps)
- Confirm design criteria (e.g. design life, materials)
- Agree on preferred fishway design if not already selected
- Develop budget estimate(s)
- Identify appropriate pre and post fish sampling regimes, budgets, outcomes
- Discuss fishway management plan (maintenance, operations, improvement)
- Discuss fishway modelling (physical and/or computer generated)
50 % detailed design process
- Complete fishway modelling (as required – e.g. physical / computational)
- Develop detailed designs
- Develop detailed cost estimate
- Develop draft design report(s)
- Develop draft fishway management plan
- Develop draft fishway monitoring plan
50 % detailed design review workshop
- Review fishway modelling
- Discuss detailed designs & report (review entrance, pools, gradient, hydrology, hydrologic operational range, attraction flows, trash racks, weir operation, fish traps)
- Confirm appropriate pre and post fish sampling regimes, budgets, outcomes
- Review fishway management plan (maintenance, operations, improvement)
- Review fishway monitoring plan
90 % design process
- Develop detailed designs
- Develop detailed cost estimate
- Develop final draft design reports
- Develop final draft fishway management plan
- Develop final draft fishway monitoring plan
- Develop draft technical specification report
90 % design review workshop
- Discuss detailed designs, reports, and costs
Final design
- Agree on final design, operation, maintenance, rectification and monitoring program
- Agreement in principle
- DPIRD Fisheries ‘signs-off’ on final fishway tender designs
- Permit issued under Fisheries Management Act 1994 (if required)
Fishway construction and commissioning
- Assess design compliance – dimensions, materials, operation, water velocity & turbulence
Implement operating & maintenance protocol
Monitor fishway
- Assess fishway performance relative to design specifications and identify any adjustments required