The Ovens River is set to benefit from a $5.1 million investment through the Victorian Government’s Building Works stimulus package to commission a Rock Ramp Fishway at Goulburn-Murray Water’s Tea Garden Creek Weir at Markwood, and a Vertical Slot Fishway (VSF) at Alpine Shire’s Bright Weir by June 2022. This will remove two of the three barriers to fish movement remaining in the Ovens, opening almost 400km of riverine habitat between the River Murray and the Ovens Headwaters.
How it works
The first significant barrier to fish movement down the Ovens River is the Bright Weir that forms the popular Bright swimming hole. In the Bright area, the Ovens River is relatively shallow, clear, and fast flowing. The fish community is dominated by an abundant population of the exotic Brown and Rainbow trout with populations of native species including River blackfish, Two spined blackfish and Mountain galaxias. There are small numbers of Murray cod and Trout cod in the upper Ovens reach, however the abundance is much higher downstream of Myrtleford along with a sizeable population of Macquarie perch.
The Bright Weir with boards in place to create the upstream swimming hole
The third barrier to fish movement along the Ovens River is the Tea Garden Creek weir at Markwood. The Tea Garden Weir supplies the Tea Garden Creek with a gravity fed water supply for irrigation and stock and domestic use in Markwood, Millawa and Oxley, where it flows into the King River. Restoring fish passage at Tea Garden weir will provide small, medium and large bodied native fish with the opportunity for unimpeded migration to upstream and downstream habitats between the River Murray and Porepunkah, including the Buffalo and Buckland Rivers. This will strengthen the populations of Murray cod and the endangered Macquarie perch and Trout cod that are present in strong numbers in this stretch of the Ovens, increasing the resilience of the entire population throughout the Murray-Darling Basin.
The Tea Garden Creek Weir at Markwood
The second barrier is the Porepunkah weir, which will remain as the only barrier to fish passage in the Ovens River. NECMA has commissioned a Detailed Design for a Vertical Slot Fishway that awaits funding for its construction.
Eighteen native fish species have been recorded in the Ovens River. Eleven are of conservation significance in Victoria or at a national level, and five of these, Murray Cod (Maccullochella peelii), Trout Cod (Maccullochella macquariensis), Macquarie Perch (Macquaria australasica), Silver Perch (Bidyanus bidyanus), and Flat-Headed Galaxias (Galaxias rostratus) are EPBC Act listed. With the construction of the Vertical Slot Fishway (VSF) at Bright and the Rock Ramp Fishway at Tea Garden Creek Weir, year-round passage will be provided for these species to migrate to habitats upstream and downstream.
Most native species undergo up and downstream migrations as an important component to their life history, usually triggered by low and rising flows. Late winter, spring and summer are the most important times for fish movement with Trout cod, Murray cod and Macquarie perch expected to migrate upstream during spring, especially on a rise in flow. Following spawning, larvae will drift downstream to new habitats. Further downstream migration can include displacement during high flow events with a return upstream migration once the flow event has passed.
Species such as River blackfish, Two-spined blackfish and the small-bodied Galaxias make localised movements (000’s metres) and are considered ‘non migratory’. However, all species will make downstream migrations to escape from poor water quality or ash flow events and will often recolonise these impacted areas upstream when water quality returns, usually over several years.
Vertical slot fishway at Bright Weir
A Vertical Slot Fishway consists of a constructed channel divided into a series of pools, separated by baffles that have a vertical slot through which water passes. The baffles/slots create a head loss so that each pool is lower than its adjacent pool upstream. Fish move upstream by passing from pool to pool, moving up through the head drop at each baffle.
Vertical slot fishway at Broken Creek, Victoria
How a vertical slot fishway works - watch this YouTube video
Features of the vertical slot fishway at Bright
- Construction will primarily be downstream of the Bright weir with a smaller entrance in the upstream weir pool. This will minimise impacts to recreation in the upper weir pool.
- A removable 0.4 m weir on the downstream side of the existing weir apron to form a plunge pool that will prevent injuries to fish moving downstream over the stopboards. The stopboards on the temporary weir can be removed and replaced with the main weir stopboards.
- A trout cell will be included at the weir crest.
- The fishway will be constructed mostly out of precast concrete panels, reducing onsite construction time and allowing the project to occur in autumn, further reducing impacts to recreation and tourists.
- Aesthetic treatments will naturalise the fishway into the surrounding riverine environment.
Rock ramp fishway at Tea Garden Weir
Rock ramp fishways are commonly used for barriers less than two metres in height and are typically constructed of angular quarry rock and strategically placed concrete baffles. The fishway slope and gap between rocks influence the discharge of the fishway, along with the internal turbulence and water velocity which controls the species and size-range of fish able to pass. Rock ramps also have interstitial spaces, capable of passing other aquatic fauna (e.g., turtles and invertebrates).
Full width rock ramp fishway on the Ovens River, Sydney Weir, Wangaratta
The fishway at Tea Garden Weir has been designed in two separate but joined segments involving:
- Construction of a 50m long x 10m wide partial width rock ramp upstream of the weir.
- Construction of a 32m full width rock ramp downstream of the weir.
- Rock placement between 250mm – 500mm to allow passage for small and large bodied fish.
The Tea Garden Creek Weir at Markwood.
Construction for both Bright and Tea Garden projects is expected to commence in early 2022 and be completed by July 2022. Throughout 2021, key stakeholders will be working together on the Project Steering Group to ensure a timely delivery with minimal disruptions to the community. Following a Design Review, community engagement will commence to provide progress updates on the project, and a conduit of contact to the project management team. Fish monitoring will be conducted by Fish Ecologists pre- and post-construction to better understand the fish community and evaluate the effectiveness of the fishway, allowing benchmarking against others in the Murray Darling Basin.
Tea Garden Project Steering Group members:
- Tea Garden Weir Irrigation Users Group
Bright Project Steering Group members: