The Friends of Horseshoe Bend near Walhalla, together with Baw Baw Shire Council, are objecting to a proposal to excavate and blast a new channel in the Thomson River at the Horseshoe Bend Diversion Tunnel. The new channel will allow fish to swim further upstream, but the works will leave tonnes of rock dumped alongside historical mining sites. The beautiful bush valley is full of archaeological relics, and the National Trust has objected to the current proposal. We are calling for a more sensitive approach to facilitate fish passage upstream with minimal impact on this cultural landscape of state significance.
The Thomson River Diversion Tunnel and Horseshoe Bend riverbed alluvial mining area was classified by the National Trust in May 2011 and includes the tunnel as well as the valley between the entrance and exit. Whilst only the tunnel and its entrance/exit is included on the Victorian Heritage Register, the archaeology of the area is protected by the Heritage Act, and that the river is included in the Heritage Rivers Act. The Horseshoe Bend area forms a historic cultural landscape of state significance, which includes the 1912 Diversion Tunnel, and an extensive scattering of mining relics around the bend in the valley:
A new fishway is proposed which essentially is a new channel cut into the river rock. While the objective of improving native fish passage to the upper Thomson catchment is sound, the current proposal does not adequately protect or maintain the natural and cultural heritage of the registered place. The current proposal will excavate or blast up to 250 metres of the Thomson River. The National Trust wrote to West Gippsland Catchment Management Authority in 2010 outlining its concerns regarding the proposed Low Flow Fishway as follows:
- the environmental and heritage impact of cutting and building an access track into the site;
- excavating the river (which in 2010 was an estimated 450 cubic metres of rock, over a distance of over 130 metres in length although no evidence was provided for these quantities and it was assumed that they could be higher);
- finding somewhere appropriate (without impact on natural or cultural heritage) to deposit the spoil from these works;
- potential problems created by stirring up mercury deposits in the river.
The deposition of tonnes of rock along the river immediately adjacent to areas on the Heritage Inventory threatens the cultural landscape of this heritage site. In addition, the installation of an access track using rock from the river is concerning, as once established, it is unlikely to be adequately rehabilitated due to compaction during construction. Even if the track was ripped prior to revegetation, the Trust has no confidence that the trail could be secured against trail bikes which could easily undo any revegetation efforts before the plants became established.
It is the view of the National Trust that the current proposal for the Horseshoe Bend fishway creates an unacceptable impact on the cultural heritage of the Thomson River Diversion Tunnel and the surrounding areas of archaeological importance, and advocates for consideration of alternative ways to facilitate the Australian Grayling’s passage to the upper Thomson.