Redundant Weir Removal: The Branch River Crossing - A Case Study

THE BRANCH RIVER Other industries that are important to the region include commercial fishing and CROSSING oyster farming, which are strongly linked to The Project local waterways and rely on a healthy catchment. The removal of the Branch River Crossing is part of a larger weir removal project History being undertaken by WWF Australia, the The Branch River Crossing was Environmental Trust of NSW and NSW constructed in 1951 by the Colonial Sugar Fisheries, with another 2 redundant weirs Refinery (CSR) for timber hauling to the to be removed over the next 12 months. mills. At that time a small township with a This project aims to increase public sawmill, school, several homesteads and awareness of the environmental effects of a general store was located beside the in-stream barriers. It provides a framework crossing. Fishing was a popular activity for to facilitate community-based weir removal the locals as both fresh and saltwater projects and demonstrates the ecological habitats were available. People also benefits of improved river health. The weir travelled upriver, by boat, from Port removal framework will assist in the Stephens to fish and to take advantage of development of similar projects throughout social occasions (Anon. 1987). Australia in the future. Current Use Location The Branch River Crossing is no longer The Branch River Crossing is located near used by CSR and is now the responsibility Port Stephens in the Karuah River of the Great Lakes Council. Land adjacent Catchment, NSW, about 22 km NNE of to the crossing is currently used for Karuah. The crossing itself is situated on a primary production, predominantly stock natural rock bar at the upper end of the grazing. A light vehicle bridge 300 m tidal limit. Water activities like boating and upstream provides a river crossing for fishing are major contributors to the area’s local traffic and heavy vehicle access is tourism industry and local economy. now possible via Booral.

“A weir is a structure (including a dam, lock, regulator, barrage or causeway) across a defined watercourse that will pond water, restrict flow or hinder the movement of fish along natural flow paths in normal flow conditions (DLWC, 2001).

Habitat now re- opened upstream of the removed crossing on the Branch River. Photo: NSW DPI. Why remove the crossing? Removal of this structure is part of a strategy to improve The crossing is acting as a the migration, breeding and weir across the Branch River. survival of native fish Construction of weirs such as populations throughout NSW. this can detrimentally affect river structure by: Removing this crossing also eliminates public liability and • preventing sediment and on-going maintenance costs for nutrient from moving along the Great Lakes Council. the waterway; THE REMOVAL PROCESS • favouring exotic species by reducing water quality and Pre-removal surveys water level variability; Pre-removal surveys were • preventing native fish from conducted to establish baseline migrating to spawn or information on water quality, expand their habitat; and fish habitat, fish species, terrestrial habitat and riparian • preventing the recruitment vegetation. Fish sampling was of native fish from other undertaken above and below areas, thus resulting in the crossing using gill nets and genetic isolation. fyke nets at set points. Catch is The presence of one or more shown in table 1. of these barriers can have a Stakeholder consultation cumulative effect on the abundance of native fish NSW Fisheries were the species and may lead to local ‘determining authority’ in the decline and even regional removal decision and were extinction of fish species responsible for deciding if the (DLWC, 2001). weir removal was going to have a significant, detrimental Removal of the crossing has effect on the environment. re-instated fish access to (Hobson 2003). The upstream habitat. This is Department of Infrastructure, important for fish species that Planning and Natural migrate between saltwater Resources (DIPNR) also and freshwater (or vice versa) carried out a study and to complete stages of their life provided comments on the cycle. Other benefits include likely biophysical impacts of the restoration of the natural water proposed weir removal. flow and tidal limit and

improved water quality. Letters were distributed to all nonagency stakeholders, including local landholders living around the project site, A break-through inviting comment on the proposed Branch River Crossing removal. Day 1 Subsequently, there was An excavator and rock breaker significant support from local were used to break through the top landholders and stakeholders. of the concrete cap on one side of Their endorsement was evident the crossing so that the excavator during discussions at the time of could work back along the removal and during interviews crossing. This enabled trucks to conducted for the production of a reverse along the crossing for video on the weir removal loading. process. Support from the local landholders and stakeholders contributed to the project’s success. The waiting game Post-removal surveys Day 1 Fish surveys will be conducted by After breaking away a small NSW Fisheries, in mid 2004, section of the crossing, a 15 hour above and below the removed interval was required to allow water crossing at the same points used levels to drop to the new height. for the pre-removal survey. This minimised the movement of suspended solids during the Discussion removal and exposed the whole structure. Native fish such as Australian bass and a number of mullet Exposed species are expected to benefit from the crossing removal as they Day 2 regularly migrate between fresh After the crossing was exposed, and saltwater. Recreational the excavator was able to break-up anglers will also benefit from the structure and remove the improved fish habitat and debris with the help of 6 tip trucks. subsequent fishing opportunities All potential issues were within the Branch River. considered including the possibility of acid sulfate material within the debris. To minimise any risk, all spoil was taken off-site.

Going….going…. Day 3 The old culverts also needed to be broken-up before being removed. Finally after 3 days of work the removal of the structure was nearly complete. The natural rock bar on which the crossing was originally built remained intact.

…Gone… Day 4 A couple of metres of the crossing was left near the edge to help maintain bank stability. The site was then cleaned-up and a clear fish passage reinstated. For the first time in 52 years, high tides are able to flood-out the natural rock bar.

Every effort was made to ensure minimal impact on the First published in December 2003 environment during the removal by WWF Australia. process. Increased turbidity © WWF Australia 2003. All Rights (suspended solids) was initially Reserved. identified as a potential issue during removal, so water quality Text: Rebecca Richardson and sampling was conducted prior, Phillip Trendell during and after works. This Design/layout: Helen Smart sampling showed that after the For copies of this brochure or a full heavy machinery work had list of WWF Australia publications stopped on Day 4, turbidity had on a wide range of conservation returned to a similar level as that issues, please contact us on: prior to removal. A downstream [email protected] or call silt trap played an important role (02) 9281 5515. in minimising turbidity increases. Environmental Trust of NSW, North Region Office WWF Removing debris from the site the Great Lakes Council and Australia PO Box 710 also assisted in minimising NSW Fisheries have proven Spring Hill QLD 4004 environmental impacts in the that a partnership approach to Tel: 07 3839 2677 Fax: 07 3839 vicinity. barrier removal can be 2633 extremely successful. There is potential for erosion of Head Office WWF Australia the upstream riverbank to occur References GPO Box 528 after removal due to scouring Sydney NSW 2001 Hobson, M. (2003). Proposed downstream of the old crossing. Tel: 02 9281 5515 Fax: 02 9281 removal of the Branch River 1060 To lessen the potential impact, a crossing - Review of couple of metres of the crossing Website: www.wwf.org.au environmental factors. NSW has been retained on both banks Fisheries, Tamworth. For more information and to promote stability under altered assistance relating to redundant hydrological conditions. Anonymous. (1987). A Place weir removal please contact: Called the Branch. Historical Conclusion WWF Australia Society, Stroud. PO Box 710 The removal of the Branch DLWC. (2001). NSW Weir Spring Hill QLD 4004 Crossing has been one of the first Inventory Database. Tel: (07) 3839 2677 in the Karuah Catchment. It is part DLWC (2001) NSW Weirs NSW DPI of a strategy to improve the Aquatic Habitat Rehabilitation migration, breeding and survival of Policy, Department of Land and Tamworth, NSW 2340 native fish populations in NSW. Water Conservation, NSW. Tel: (02) 6765 4591 The success of this project will Email: encourage similar projects in the [email protected] future and promote the removal of Website: www.dpi.nsw.gov.au redundant weirs as a new and exciting option for river rehabilitation. WWF Australia,

Funding and support for the Branch Crossing removal was provided by the Environmental Trust of NSW, NSW Fisheries, Recreational Fishing Trust and the Great Lakes Council