Instream Barrier Assessment and Prioritisation of the Lower Barwon River and Otways Streams

Instream Barrier Assessment and Prioritisation of the Lower Barwon River and Otways Streams A report for the Corangamite Catchment Management Authority Environous, Kingfisher Research and Arthur Rylah Institute for Environmental Research (DSE) Published by: Environous PO Box 86, Queenscliff, Victoria, 3225 Telephone: (03) 5258 1831 Email: [email protected] Also: Kingfisher Research 20 Chapman Street, Diamond Creek, Victoria 3089 And: Arthur Rylah Institute for Environmental Research Department of Sustainability and Environment PO Box 137, Heidelberg, Victoria, 3084 Produced for: Corangamite Catchment Management Authority 64 Denis Street, Colac, Victoria, 3250 This publication may be cited as: Ryan, T., Stuart, I., O’Brien, T. and Saddlier, S, (2010) Instream Barrier Assessment and Prioritisation of the Lower Barwon River and Otways Streams. Report for the Corangamite Catchment Management Authority. Cover photographs: from top left to right: tidal barrage weir and fishway on Thompson Creek @ Minya; diversion weir on Erskine River below Erskine Falls; culvert fishway on lower Cumberland River; gauging weir on Lardners Creek gauging @ Gellibrand East Road. This document was produced by environous Pty Ltd. for the Corangamite CMA and may only be used for the purposes and in accordance with the Terms of the Engagement for which it was commissioned. Instream Barrier Assessment and Prioritisation of the Lower Barwon River and Otways Streams EXECUTIVE SUMMARY At least 10 of the 16 freshwater fish species found in the Corangamite Catchment need to migrate between freshwater and estuarine or marine habitat as an obligatory part of their life cycle. The other five freshwater fish species also benefit from unrestricted movement to access a variety of habitats including appropriate breeding, nursery and feeding habitats. This movement also prevents fragmentation, reduces susceptibility to disease and extinction, and maintains genetic diversity and as such is particularly important for survival of threatened or rare fish species. Man-made structures can prevent or limit fish passage through the creation of a physical blockage, a hydrological barrier, or by forming artificial conditions that act as behavioural barriers to fish. The impact of these barriers on fish passage will vary depending on the design of the structure as well as stream hydrology and geomorphology characteristics including the integrity of seasonal flows and corresponding migrational capabilities of individual fish species. This report provides a summary of a comprehensive field assessment of fish passage barriers in streams within the Corangamite Catchment. All potential fish passage barriers were prioritised according to their respective ecological impact and potential ecological benefits for restoration. The Corangamite CMA has been proactive and has already restored fish passage at some of the priority fishways identified in this report. Further fish passage restoration at priority locations combined with a strategic fish monitoring program and regular fishway inspection and maintenance programs will ensure the recovery and maintenance of native fish biodiversity in the region. The Corangamite Catchment Management Authority (CCMA) has undertaken fish passage restoration at many locations. A number of additional barriers in coastal streams have previously been identified and prioritised for fish passage restoration. This report provides a comprehensive review of all potential barriers to fish migration and the existing fishways in streams throughout the Otways coast from the lower Barwon River at Geelong to the Curdies River at Peterborough. The overall aim of this project is to identify all potential barriers to fish passage in coastal streams in the Corangamite region (i.e. in streams of the Otways coast from the Barwon River at Geelong (lower Barwon River only) to the Curdies River at Peterborough). These barriers are prioritised on the basis of ecological significance as well as estimated cost of providing fish access. This information will then be used to develop a management plan for fish passage. The specific objectives and outcomes of the present study are to: 1. Undertake a desktop review of the current information on identified barriers 2. Undertake field assessments of the barriers where required 3. Prioritise the barriers in terms of benefits of fish passage and for remediation works 4. Develop an action plan for restoring fish passage 5. Develop a strategic fish passage plan with preferred fishway options for the highest priority sites in each river system and in each coastal program area (Barwon Bellarine/Thompson, Aire/Otways, Curdies/Gellibrand) 6. Make management recommendations including the steps of rehabilitation based on the prioritisation and approximate cost fishway designs. Environous, Kingfisher Research & Rylah Institute for Environmental Research i Instream Barrier Assessment and Prioritisation of the Lower Barwon River and Otways Streams Barrier prioritisation was based on desktop reviews of available information (aerial photography, CCMA databases, and other available databases). A total of 347 potential fish barriers were identified and subsequently inspected to collect an extensive suite of information including the: diversity of fish communities present, occurrence of threatened fish species, relative location of fish barriers within the catchment, size of individual stream barriers, relative ease of fish passage restoration, and quality and quantity of potential upstream habitat. This information was assessed using a set of criteria to prioritise the order in which those barriers with greatest ecological benefit should be rectified. Priority sites for fish passage restoration were identified in each of the three main coastal regions of the CCMA (summarised in the table on page iv). Estimated total costs were also provided based on the previous experience of the project team. Priorities for the Lower Barwon, Bellarine and Thompson 1. Restoration of fish passage in the Barwon River was estimated to cost $670,000. This is an important system regionally and restoration should be undertaken as a matter of priority. It is recommended that restoration commence with a new vertical-slot fishway at the lower barrage (~$150K) closest to the river mouth, followed by a rock ramp refurbishment upstream at Pollocksford Weir, as a relatively inexpensive (~$20K) restoration. Reedy Lake regulator, Buckleys Falls and Baums Weir also require significant restoration activity. Additional fishways, preferably vertical-slot designs, are recommended for these sites (~$150K, ~$200K and ~$150K, respectively). 2. Restoration of fish passage in Waurn Ponds Creek (up to Jarvis Oval) would be relatively inexpensive with barrier removals at two locations (~$10K) and pedestrian causeway replacements at two locations (~$70K collectively). 3. Restoration of fish passage to the lower Thompson Creek was also recognised as a high priority and included a new vertical-slot fishway at the lower weir at Minya (~$150K) and a relatively inexpensive (~$20K) restoration/refurbishment of the rock ramp and culvert fishway at Horseshoe Bend Road. Priorities for the East Otways Streams to Aire River 1. Restoration of fish passage in the St Georges River was recommended as the highest priority with replacement of the pedestrian causeway with a single span bridge (~$30K) in the lower reaches and removal of an old gauging weir (~$20K) downstream of Allenvale Road. The major barrier represented by Allen Reservoir was not considered to be a high priority regionally, but may need to be considered at a later date. 2. Various low cost modifications were ranked highly in terms of value for money; these included Carisbrook Creek (~$5K), Cumberland River (~$5K) and Painkalac Creek (~$10K). 3. A number of other low cost fish passage restoration works were indentified, including modification of three private causeways on Grassy Creek (~$30K collectively) and two on Skenes Creek (~$80K collectively). 4. Refurbishment of the rock ramp at the Barham River East Branch gauging station (~$15K) was identified as one of the highest priority on the Barham River catchment. 5. The restoration of fish passage in the Anglesea River should also be undertaken with the replacement of culvert causeways with single span bridges (or box culverts) (~$210K collectively). ii Environous, Kingfisher Research & Rylah Institute for Environmental Research Instream Barrier Assessment and Prioritisation of the Lower Barwon River and Otways Streams 6. Causeway replacements with single span bridges were also recommended at ‘Oldenzaal’ on the Barham River East Branch and Montrose Avenue on Anderson Creek (~$70K each). 7. The numerous pipeline crossings on the Barham River West branch leading up to the large water storage weir further upstream were also identified collectively as a high priority and would be relatively inexpensive to rectify (~$40K). 8. New rock ramp fishways were also high on the priority list on Moggs Creek (~$30K) and Aire River (~$40K) Priorities for the West Otways Streams to Curdies River 1. Restoration of fish passage in the Gellibrand River was identified as an important and relatively simple process. Refurbishments of rock ramps at stream gauges at Lyness Road and below Stevensons Falls, and the complete removal of an old stream gauge near Clancys Access were considered to be high priorities (~$35K collectively). 2. Fish passage recommendations for the Curdies River catchment include rock

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