PROPOSED RAISING OF CLARRIE HALL DAM FINAL REPORT PROPOSED RAISING OF CLARRIE HALL DAM FINAL REPORT ... Proposed Raising of Clarrie Hall Dam ... A.2 OLD FARMLAND IN BACKGROUND WITH

PROPOSED RAISING OF CLARRIE HALL DAMFINAL REPORT

Identification of Issues and Constraints of Proposal

Prepared forNSW DEPARTMENT OF COMMERCE

by

Greenloaning Biostudies Pty. Ltd.ACN 075 037 56293 Wyrallah Road

East Lismore, NSW 2480

April 2008

Greenloaning Biostudies Pty Ltd Page i

0705001RP3 - MASTER FINAL REPORT APRIL 2008

REPORT NO. 0705001RP3

The preparation of this report has been in accordance with the brief provided by the Client and has

relied upon the data and results collected at or under the times and conditions specified in the report.

All findings, conclusions or recommendations contained within the report are based only on the

aforementioned circumstances. The report has been prepared for use by the Client and no

responsibility for its use by other parties is accepted.

Approved by: Alison Martin

Position: Project Director

Signed:

Date: 2 April, 2008

Greenloaning Biostudies Pty Ltd Page ii


Document Control Sheet

Original Date of Issue: 04-12-07Archive Document No.: 0705001RP3Project Manager: Alison Martin

Project: Proposed Raising of Clarrie Hall DamReport Title: Proposed Raising of Clarrie Hall Dam - Identification of Issues and

Constraints of ProposalReport Number: 0705001RP3Authors: Alison Martin/Dr David Robertson

Client: NSW Department of CommerceClient Contact: Margaret Balandin

REVISION/CHECKING HISTORY

FIGURES

INCLUDEDREVISION

NUMBERYES NO

DATE SENT TO

CLIENT/PRIMARY

CONSULTANT

CHECKED BY/SENT BYDATE COMMENTS

RECEIVED FROM CLIENT

1 04-12-07Alison Martin/DavidRobertson

1 05-12-07 Julia Bartrim 19-12-07

2 23-01-08 Alison Martin 04-03-08; 25-03-08

3 27-03-08 Alison Martin

REVISION/METHOD OF DISTRIBUTION

REVISION NUMBERMETHOD OF

DISTRIBUTION

DESTINATION 1 2 3 4 5 6 7 Final E D F H

Dpt of Commerce, Sydney

Dpt of Commerce, Sydney

Please indicate one of the following methods of distribution by inserting in appropriate box

KEY: E E-Mail F Fax H Hard Copy D Digital

Greenloaning Biostudies Pty Ltd Page i


Table Of Contents

EXECUTIVE SUMMARY

Flora and Fauna 6

Recommendations 8

Priority 1 8

Priority 2 8

Priority 3 8

1. INTRODUCTION

1.1 Background 1.1

1.2 Purpose Of Report 1.2

1.3 Scope Of Works 1.3

1.4 Study Area Characteristics 1.4

1.4.1 Local Setting 1.4

1.4.2 Regional Setting 1.7

1.5 Document Review 1.7

1.6 Report Structure 1.8

1.7 Terminology 1.9

2. PROJECT OUTLINE AND POTENTIAL IMPACTS AND ISSUES

2.1 Description Of Proposed Works Associated With Raising The Dam 2.1

2.2 Potential Impacts Relating to Flora, Fauna and Aquatic Ecosystem 2.2

2.2.1 Construction Phase 2.2

2.2.2 Operations Phase 2.3

2.3 Potential Issues Relating to Flora, Fauna and Aquatic System 2.6

2.4 Key Threatening Processes In NSW 2.6

Greenloaning Biostudies Pty Ltd Page ii


Table Of Contents

3. METHODOLOGY

3.1 Desktop Assessments 3.1

3.2 Site Inspections 3.1

3.3 Risk Assessments 3.2

4. STUDY RESULTS

4.1 General Ecological Attributes of the study area 4.1

4.2 Aquatic Ecosystem 4.1

4.2.1 Aquatic Flora 4.1

4.2.2 Aquatic Fauna 4.2

4.3 Terrestrial Flora 4.3

4.4 Terrestrial Fauna (including water-dependent species) 4.12

4.5 Overall Ecological Values of the Project Site And Study Area Biota 4.14

4.5.1 Aquatic Ecosystem 4.14

4.5.2 Terrestrial Flora and Fauna 4.14

4.5.3 Corridor and Vegetation Network Values 4.16

5. IDENTIFICATION OF ISSUES AND CONSTRAINTS

5.1 Risk Assessment for Potential Impacts Arising from the ProposedWorks

5.1

5.2 Key Issues and Constraints 5.4

5.2.1 Key Issues Identified 5.4

5.2.2 Constraints to Project 5.5

6. CONCLUSIONS AND RECOMMENDATIONS

6.1 Conclusions 6.1

6.2 Recommendations 6.2

Greenloaning Biostudies Pty Ltd Page iii


Table Of Contents

6.2.1 Priority 1 6.2



Table Of Appendices

A. PHOTOGRAPHS

List of Tables

4.1 THREATENED/SIGNIFICANT FLORA SPECIES RECORDED WITHIN 5AND 10 KM FROM CLARRIE HALL DAM 4.8

4.2 THREATENED FAUNA SPECIES RECORDED WITHIN 5 AND 10 KMFROM CLARRIE HALL DAM 4.10

5.1 RISK ASSESSMENT FOR POTENTIAL IMPACTS 5.2

Greenloaning Biostudies Pty Ltd Page iv


List of Figures

1.1 LOCALITY PLAN AND PROJECT SITE (SOURCE NSW DEPARTMENTOF LANDS SIX VIEWER © SIX.MAPS.NSW.GOV.AU) 1.2

1.2 TOPOGRAPHICAL FEATURES OF THE STUDY AREA 1.5

1.3 SATELLITE IMAGE OF THE EXISTING DAM AND SURROUNDINGFEATURES (SOURCE NSW DEPARTMENT OF LANDS SIX VIEWER ©SIX.MAPS.NSW.GOV.AU) 1.6

2.1 PROPOSED INUNDATION AREA (MAP PROVIDED BY DOC) 2.4

4.1 TWEED SHIRE VEGETATION MAP (SOURCE DEPARTMENT OFENVIRONMENT AND CLIMATE CHANGE 2007) 4.6

4.2 THREATENED FLORA SPECIES WITHIN THE LOCALITY 4.7

4.3 THREATENED FAUNA SPECIES WITHIN THE LOCALITY 4.17

5.1 PRELIMINARY POTENTIAL CONSTRAINTS 5.6

List of Photographs

A.1 OPEN WATER BODY OF CLARRIE HALL DAM WITH MT WARNINGIN BACKGROUND, OLD FARMLAND ON RIGHT AND WETLANDVEGETATION ON RIGHT HAND FRINGE A.1

A.2 OLD FARMLAND IN BACKGROUND WITH DENSE WATER LILY BEDIN FOREGROUND A.1

A.3 RAINFOREST POCKET ON FRINGES OF SIDE ARM OF THE DAM A.2

A.4 RAINFOREST ELEMENTS REGENERATING ON DAM EDGES A.2

A.5 SHELTERED SIDE ARM OF CLARRIE HALL DAM WITH DEAD TREESAND WETLAND VEGETATION A.3

Greenloaning Biostudies Pty Ltd Page v


List of Photographs

A.6 REGENERATING RAINFOREST WITH BANGALOW PALMS A.3

A.7 HABITAT FEATURES WITH DEAD STANDING TRESS, LOGS, OPENWATER AND WATER LILY BEDS A.4

A.8 COMB-CRESTED JACANA UTILISING DENSE WATER LILY BED A.4

Greenloaning Biostudies Pty Ltd Page S.1


Executive Summary

Background and Purpose of Report

Greenloaning Biostudies Pty Ltd has been contracted by the Department of Commerce toconduct preliminary investigations of the potential ecological impacts associated withincreasing the capacity of the Clarrie Hall Dam. Clarrie Hall Dam (the project site) is anexisting water supply dam that was completed in 1983 to service the Tweed Shire. Thedam is located approximately 15 km south-west of Murwillumbah and 650 km north ofSydney. As a result of increasing water demand within the Tweed Shire, Tweed ShireCouncil has been investigating the option of increasing the available yield of Clarrie HallDam by raising the existing storage full supply level. Investigations are thereforecurrently being undertaken into potentially raising Clarrie Hall Dam by 10 m, the dam tobe operated at RL 70 to allow sufficient capacity for storm surcharges.

As part of the dam raising investigations, an issues and constraints report for the preferredraising option is required. This report addresses the requirement for assessing potentialflora and fauna issues on a preliminary basis. It examines the type and extent of impactson flora and fauna likely to arise from the proposed dam raising process and identifiespotential issues and constraints on the project arising from flora and fauna components ofthe project site. The aim of the report is also to provide recommendations regardingfurther surveys required as part of the more detailed assessment process that would beexpected to follow from the initial assessment process underlying this report.

Scope of Works

The preliminary assessment is required to consider both terrestrial and aquatic flora andfauna impacts for both the construction and operation stages of the project. Specifiedtasks to be included in the assessment process comprise:

Relevant database searches;

Review of aerial photographs, vegetation plans (or similar) and other backgroundinformation applicable to the region;

Site reconnaissance investigations;

Descriptions of the general ecological character of the area and review of theconservation significance of known (terrestrial, riparian and aquatic) flora, faunaand vegetation communities;

Mapping of sensitive areas;



Provision of an overview of the likely ecological issues associated with both theconstruction and operation of the proposal and relevant recommendations on theextent of any detailed flora and fauna surveys which may be required; and

Documentation of the findings in an overview report.

Study Area Characteristics

The project site and study area are located in the upper reaches of the Tweed Rivercatchment within the Tweed Shire, 15 kilometres south west of Murwillumbah and withina few kilometres of the small village of Uki. The area forms part of the remnant caldera ofthe Mount Warning shield volcano, Mt Warning itself being located just to the north westof the project site. Currently Clarrie Hall Dam represents the largest fresh-water body inthe locality and the Tweed Shire, other larger water bodies in the shire having salineinfluences.. The waters of Clarrie Hall Dam are enclosed largely within the steep sidedvalleys of Doon Doon Creek and its tributaries. Much of the immediate surrounds of thedam is characterised by steep slopes and narrow creek gullies.

The Clarrie Hall Dam study area and locality are part of the North Coast bioregion whichis a region of very high biodiversity at both a national and international level. Althoughmuch of the regional landscape and original vegetation cover is somewhat fragmented,the area still supports important remnant vegetation and regional wildlife corridors.Aquatic systems within the region are also high in biodiversity.

Project Description

Suitable options for raising Clarrie Hall Dam have been developed, the options taking intoaccount engineering, social and environmental factors, as well as efficiency,constructability and economy. Preliminary hydraulic and structural designs have beencarried out to confirm the options' layout and dimensions. The current full supply level ofthe dam is at RL61.5m with a storage capacity of 16,000ML. It was subsequentlydetermined that the dam’s maximum optimum size, based on economic analysis, waswith FSL at RL70.0m and storage capacity of about 42,300ML. The optimum size will alsobe reassessed based on other factors such as flora and fauna and cultural heritagecomponents.

A number of dam raising options were short listed for further investigation. All of thedam raising options have been developed to pass the Probable Maximum Flood level andall options require the existing intake tower to be raised. For all spillway options, a fullyconcrete lined channel is proposed due to the highly fractured nature of the rock.

Potential Impacts

The total estimated area of inundation is predicted to be 230 ha (Full Supply Level) and atotal of 320 ha under the flood inundation scenario. Current inundation is approximately220 ha. A number of impacts, either direct or indirect, could be anticipated as a result ofthe project development, either during the construction and/or the operation phase.These potential impacts give rise to a number of potential issues associated with the



proposed dam raising works and relating to flora, fauna and aquatic ecosystems. Theseinclude:

Known or likely occurrence of threatened species within habitats likely to beremoved/modified;

Modification or loss of existing corridor values with modification/loss of somespecific habitat types (e.g rainforest);

Long term modification to the existing aquatic ecosystem and potential short termloss of high value habitat;

Eutrophication of the existing water body;

Off-site impacts and altered flow regimes affecting downstream habitats; and

Increased risks to threatened species/habitats associated with increaseddisturbance to the project site.

Methodology

Prior to visiting the site, preliminary desktop assessments and background research wereundertaken. In addition, some time was spent perusing Council databases and mappingprogrammes to examine such aspects as areas of sensitive habitat and wildlife corridors inrelation to the study area.

A site inspection of the existing dam facility, surrounding study area and general locality,was conducted over a two day period on the 11th and 12th of September 2007. Datacollected during the site inspections was restricted to taking notes on general habitat typesor specific records occurring at various locations and marking their locations on a 1:25000topographical map and taking photographs of representative or significant areas/habitatsoccurring along the dam edges and surface.

Aquatic Ecosystem, Flora and Fauna Components

Aquatic Ecosystem

All available information indicates that the locality has high biodiversity and alsosupports a high number of threatened terrestrial flora and fauna species, including speciesdependent of sclerophyll, or more typically rainforest habitats, as well as a small numberof water dependent species such as the Black-necked Stork. The central and northernportions of the dam are fringed by an almost continuous belt of vegetation, whilst thesouthern portion encompasses areas of old farmland, with some open grassland, varyingamounts of natural regeneration and extensive shallow wetlands.

Previous studies of Doon Doon Creek found that the aquatic system provided importanthabitat for small forage fish. Phytoplankton and aquatic plants were also a very importantpart of the food chain. The most notable fish of recreational significance were theAustralian Bass, the Freshwater Catfish, the Sea Mullet and the Freshwater Mullet. Several



Platypus were also sighted in Doon Doon Creek during the course of the previoussurveys.

The construction of Clarrie Hall Dam has provided a large freshwater reservoir formedwithin largely basaltic catchment areas that supply high nutrient levels. These highnutrient levels and the abundant shallow areas, have given rise to extensive beds of WaterLilies (Nymphaea spp.) and some reed beds. The waters of the reservoir are known tosupport a broad assemblage of fish species, with Australian Bass (Maquaarianovemaculeata), the most sought after species by anglers and regularly stocked in the dam.Currently however, there is no fish ladder to facilitate passage of fish upstream into thedam.

Given the diversity of habitats in the dam and the productivity of the macrophytes thatoccur, it is probable that there is currently a much higher diversity within the existing damaquatic system than was reported for the original aquatic system of Doon Doon Creek.

Flora

Previous studies for the Clarrie Hall Dam site prior to the construction of the dam (Parkerand Parker 1979) found that, in broad terms, the area surrounding the Clarrie Hall damsupported communities of dry rainforest intermingling with pockets of warm temperate,subtropical rainforest and wet sclerophyll forest. These communities were characteristicfor the locality. One significant species, Milletta australis, (now known as Callerya australis)considered at the time to be rare and endangered and currently listed as "Rare" underROTAP Code: {3RC-+ (-C- & -Ci NC)}, was also recorded from the rainforest communitywithin the then proposed inundation area during the previous studies (Parker and Parker1979). Two additional species now listed as threatened, Durobby (Syzygium moorei) andSweet Myrtle (Austromytrus fragrantissima) (then recorded as Gossia fragrantissima) werealso recorded.

Current information available indicates that a rich diversity of threatened flora speciesoccur within a 20 kilometre radius from Clarrie Hall Dam. Key features of the existing sitevegetation include a relatively healthy fringe of mainly sclerophyll forest/regeneratingforest surrounding most of the existing water body, with some pockets of warm temperateand subtropical rainforest occurring in a few locations just above the existing water level.The riparian zone downstream from the existing spillway also retains a variable cover ofRiver Oak Forest.

There are also large expanses of aquatic vegetation, generally dominated by native waterlilies, occurring in many of the shallow edges and side arms of the existing dam. Thevegetation mapping conducted within the Tweed Shire indicates that a variety ofcommunities still occur within the study area, communities occurring including primarilymost sclerophyll forest types and some areas of subtropical/warm temperate rainforest;and early regrowth rainforest.



Fauna

Previous fauna studies for the Clarrie Hall Dam site prior to the construction of the damfound that the area supported a range of species representative of the area, none of whichwere considered threatened at that time. The Red-legged Pademelon (Thylogale stigmatica)however, is now listed as threatened under the TSC Act (1995) and was recorded withinthe area described as Area 1 within the previous study area (within the southern sector ofthe current inundation area).

Given that the majority of habitats previously recorded within the study area are stillrepresented to varying degrees, based on the current data available, the majority of faunaspecies recorded previously would be expected still to occur. Regeneration of a number ofhabitats on the existing dam perimeter has also progressed over the last two decades andthis would be expected to have encouraged some recolonisation by fauna species. Theexisting dam however, inundated the majority of rainforest habitat occurring in the studyarea and rainforest dependent fauna would therefore be expected to be less representedthan previously.

Two threatened fauna species, the Comb-crested Jacana and the Black-necked Stork, areknown from the project site and existing dam facility wetlands. The Comb-crested Jacanain particular, appears to be relatively common, frequenting the extensive Water Lily bedsthat occur on the existing water body. An additional eleven of the threatened speciesrecorded within 10 kilometres from the project site are considered likely to occur withinthe project site/study area.

Key features of the site fauna habitats/species identified during the recent site inspectionsinclude primarily healthy dry/moist sclerophyll forest habitat fringing the majority of theexisting water body, supporting areas of potential food trees for threatened species suchas the Koala and Glossy Black Cockatoo and pockets of rainforest habitat adjoining largerareas of other moist forest habitat. There are also large expanses of wetland habitat,supporting extensive Water Lily beds, as well as some sectors of reeds and other wetlandvegetation occurring in many of the shallow edges and side arms of the existing dam. Thecombination of the open water of variable depths and the vegetated shallows provides arange of habitat resources for waterbird species and other water dependent species.Substantial occurrence of stags (dead trees) occurring in sheltered side arms of the damalso offer high value roosting habitat for water birds and sheltered riparian habitat, albeitdisturbed with a rocky stream bed and some water flow remains downstream from theexisting spillway. A proportion of these trees would also provide roosting/breedinghollows for mobile arboreal species such as microbats and hollow-nesting birds.

Overall Ecological Values of the Project Site and Study Area Biota

Aquatic Ecosystem

The construction of a dam, has resulted in a large productive body of water with variableextents of fringing shallows, has enabled the development of a substantial wetland habitatunique within the locality. The littoral wetlands and the lake waters have significantvalue as a resource, particularly for aquatic species such as water birds, platypus, aquatic



macroinvertebrates, frogs, snakes, other reptiles and fishes. The existing dam also hasvalue as fish habitat, providing both ecological and recreational values to the locality. TheBass fishery is a significant and well known resource for recreational freshwater fishing.

Flora and Fauna

Generally the flora and fauna components of the project site and study area (as defined inSection 1.7 of this report) are reasonably representative of the locality and local area (alsodefined in Section 1.7. There are some specific components of the site that have highvalue, as indicated in part by the number of threatened species known or potentiallyoccurring within the study area. This is primarily reflective of the high value rainforestand wetland habitats, although the overall value of the rainforest habitats is likely to belimited because of their current small size. These small rainforest pockets could however,still support specimens of rare/threatened plant species, particularly considering thatsuch pockets have also apparently undergone considerable regeneration since the damconstruction and two threatened tree specimens were previously recorded.

Further substantial value is added by the extensive development of freshwater wetlandhabitats, some of which would be likely to conform to the definition of the CoastalFreshwater Wetland EEC.

Much of the habitat within the study area is likely to be of moderate value, taking intoaccount previous levels of disturbance. The moderate evaluation of the more widespreadhabitats is derived from the relatively modified structure of the forested systems, theprevalence of young mature tree species with a paucity of hollows and long term effectsfrom clearing/grazing/fire. These habitats would therefore be expected to support arange of flora and fauna species to some extent but those species requiring the habitatfeatures that have been depleted (such as tree hollows) would not be expected to be wellrepresented. The overall biodiversity value of such habitats however, is also likely to beincreasing over time with the continued natural regeneration of habitats surrounding theexisting water body. The current status of these habitats would also not preclude theoccurrence of some threatened species.

A large number of threatened bird species have been identified in the surrounding areaand both the Black-necked Stork, listed as endangered under the TSC Act, and the Comb-crested Jacana, listed as vulnerable, have also been recorded on the Clarrie Hall Dam site.The apparent high value of the site to the latter species adds substantially to the overallecological value of the project site and study area.

The key values of the project site identified to date include:

Known occurrence of potential Endangered Ecological Communities (LowlandRainforest and Coastal Freshwater Wetland) and potential habitat for threatenedflora species;

Known occurrence of threatened fauna species (the Comb-crested Jacana andBlack-necked Stork) and the likely site dependency of the Comb-crested Jacana;



Known occurrence of potential habitat for threatened fauna species (such as theKoala); and

Extensive occurrence of freshwater wetland habitat for waterbirds, includingpotential habitat fro a number of species listed as migratory under the EPBC Act(1999).

In addition, the study area forms part of a sub-regional corridor that connects the studyarea and environs with other similar and/or larger expanses of habitat and providesconnectivity with such habitat for fauna species and seed dispersal. The study area alsofalls within the Border Ranges Hotspot Biodiversity Management Plan study area.

Conclusions and Recommendations

The construction of the existing Clarrie Hall Dam has resulted in the permanentinundation of some areas of significant vegetation types, particularly rainforestcommunities, and impacted on a small number of threatened flora and fauna speciesand/or their habitats. However, the creation of a large water body and the developmentof substantial areas of freshwater wetland, together with the natural regeneration ofvegetation around the existing dam perimeter, has resulted in a valuable, albeit artificial,ecological attribute and aquatic system in the Tweed Shire.

The proposed raising of the dam to RL 70 will result in the additional inundation of somesignificant vegetation communities and fauna habitats and modification of the wetlandhabitats and aquatic system that have developed over the last 25 years. Some adverseimpacts on threatened species and communities likely to conform to EndangeredEcological Communities descriptions (Lowland Rainforest on Floodplain and CoastalFreshwater Wetland on Floodplain) would be expected and impacts on the Comb-crestedJacana in particular would be likely to be significant.

On the basis of currently available data and recent on-site observations, the majority of theissues identified are not likely to pose major constraints to the project providing the issuesare dealt with appropriately and sufficient information is obtained to allow adequateassessments of potential impacts. Some issues identified however, would be more likelyto pose substantial constraints on the project, including:

Requirements for downstream flows within the Tweed River system ;

Water quality issues associated with releases from a deeper storage;

The occurrence of any endangered species and/or Endangered EcologicalCommunities within the proposed inundation area;

Threatened or migratory fauna occurrence, primarily with a dependence on theproject site habitats and subject to direct impacts from the proposed dam raising;and

Requirements for the provision of compensatory habitat.



Existing downstream flows, likely previous natural flows and likely new flows followingraising of the dam are currently being investigated by Dr Keith Bishop. Although aquaticecosystems within the dam are likely to benefit in the medium to long term, in the shortterm, there will be disruption to aquatic ecology and it is likely that littoral communitieswill take several years to re-establish. In the interim, key species dependent upon themwill be impacted. Some may benefit in the short term, whereas others such as the Comb-crested Jacana, a vulnerable bird species, may be displaced until the lily pads that itdepends upon are regenerated.

Delineation of potential offsets to the wetland habitat and rainforest likely to be removedand/or modified would lessen the long term impacts and be likely to lessen theconstraints on the project overall.

A significant issue associated with the proposal as it currently stands is a lack of definitiveinformation on the extent of expected inundation on the ground and correspondingdetailed mapping. Such information is a priority to allow subsequent impact assessmentsand offset potentials (such as extent of shallow wetlands to be created) to be determined.

RECOMMENDATIONS

In order to address the current issues identified for the project and thereby minimisepotential ecological issues, it is recommended that a number of priority actions beundertaken. These are, in order of priority.

Priority 1

As an immediate priority, attention be given to ensuring that the mapping of RL 70 onrelevant data layers held by Council is accurate and clearly shows the expected extent ofimpact when overlain over such layers as vegetation communities.

Priority 2

Ensure that the proposed construction footprint also is accurate when overlain over suchlayers as vegetation communities.

Priority 3

Conduct further surveys and assessments of potential impacts on the following aspects;

Aquatic flora and fauna currently occurring both downstream from and withinthe existing dam and key habitat requirements/existing habitat characteristics(such as water quality, temperature). These studies would need to considercurrent and likely future fish passage patterns;



Definition and mapping of current vegetation communities within the study areaand assessment of EEC status, with particular focus on the area within theproposed inundation area and including a 50-200m perimeter area (this area to bedefined following completion of priority actions 1 and 2 above);

Target searches for threatened flora and fauna species, the final determination ofsubject species to be made following completion of priority actions 1 and 2 aboveand taking the dot point above of action 3 into consideration;

More detailed assessments and comparisons of the study area in a local context beundertaken; and

Conduct a more detailed analysis of the feasibility of creation of a fish ladder toaddress the issue of upstream fish passage into the dam or alternativelyinvestigate offsets for fish passage downstream.

It is recommended that further fauna field surveys cover all fauna groups, and surveylocations be restricted to the inundation area and immediate perimeter. Surveys shouldbe carefully designed to sample representative habitats and for practical reasons,consideration should also be given to co-ordinating the aquatic and terrestrial surveys.Timing of surveys would be important for a number of species. It is recommended thatsubsequent target survey design incorporate a final detailed schedule to ensure all targetspecies are sampled at an appropriate time with as much overlap in survey times aspossible to maximise survey efficiency. Two seasons of surveys would be recommended,likely optimal survey periods being spring and late summer/autumn.

A preliminary list of target species would include, but not be restricted to:

Flora

White Lace-flower (Archidendron hendersonii);

Heart-leaved Bonewood (Bosstoa selwyni);

Thorny Pea (Desmodium acanthocladum);

Small-leaved Tamarind (Diploglottis campbellii);

Rusty Rose Walnut (Endianda hayesi);

Green-leaved Rose Walnut (Endiandra muelleri subsp.bracteata);

Sweet Myrtle (Gossia fragrantissima);

Rough-shelled Bush Nut (Macadamia tetraphylla);

Pygmy Bishop’s Hat (Mitrasacme pygmaea);

Onion Cedar (Owenia cepiodorqa); and



Hartman’s Sarcochilus (Sarcochilus hartmannii).

Fauna

Bush Hen (Amauornis olivaceus);

Black-necked Stork (Ephippiorhynchus asiaticus);

Comb-crested Jacana (Irediparra gallinacean);

Glossy Black Cockatoo (Calyptorhymchus lathami);

Double-eyed Fig Parrot (Cyclopsitta diophthalma coxeni);

Alberts Lyrebird (Menura alberti);

White-eared Monarch (Monarcha leucotis);

Blue-billed Duck (Oxyura Australia);

Wompoo Fruit Dove (Ptilinopus magnificus);

Eastern Long-eared Bat (Nyctophilus bifax);

Greater Broad-nosed Bat (Scoteanax rueppelli);

Koala (Phascolarctos cinereus);

Red-legged Pademelon (Thylogae stigmatica);

Green-thighed Frog (Litoria brevipalmata);

Great Barred Frog (Mixophyes iterates); and

Loveridge’s Frog (Philoria loveridgei).

During the final assessment process, it is recommended that substantial attention be givento the potential for both wetland and rainforest community offsets and the overall longterm management of the study area environment, particularly with regard to firemanagement, threatened species objectives and water weed management.

Greenloaning Biostudies Pty Ltd Page 1.1


Chapter 1.

1 Introduction

1.1 BACKGROUND

Greenloaning Biostudies Pty Ltd has been contracted by the Department of Commerce toconduct preliminary investigations into the potential ecological impacts associated withincreasing the capacity of the Clarrie Hall Dam. For the purposes of this report,background information on the existing dam structure and the proposed works has beendrawn primarily from the briefing document and the draft report on optimum size andoptions (Department of Commerce 2007) provided by the Department of Commerce.

Clarrie Hall Dam is an existing water supply dam that was completed in 1983 to servicethe Tweed Shire. The dam has a catchment area of 60 square kilometres and a storagecapacity of 16,000 ML. The dam is located on Doon Doon Creek, approximately15 kilometres south-west of Murwillumbah and 650 kilometres north of Sydney.Doon Doon Creek is a tributary of the South Arm of the Tweed River. The main accesspoint to the dam is approximately four kilometres south-west of Uki, via Clarrie Hall DamRoad, which runs off Main Road No 142 (Kyogle-Murwillumbah). The location andrelevant road systems are shown in Figure 1.1

Clarrie Hall Dam is a concrete-faced rock fill dam 43 metres high, with a crest length of180 metres. The existing water body is approximately four kilometres long and onekilometre wide at its widest point, covering an area of approximately 220 hectares (ha).

As a result of increasing water demand within the Tweed Shire, Tweed Shire Council hasresolved to assess the potential to increase the available yield of Clarrie Hall Dam byraising the existing storage full supply level. Investigations are therefore currently beingundertaken into the feasibility of raising Clarrie Hall Dam by 10 m (referred to hereafter as“the preferred option”). Based on economic factors to date, it is proposed that the damwould be operated at RL 70 allowing sufficient capacity for storm surcharges.

The works would involve;

Stripping the existing rock fill from the dam face,

Construction of a new spillway channel adjacent to the dam wall. Materialquarried for the spillway construction would be used to raise the dam, and

Raising the height of the dam wall to RL 77 (however the dam would be operatedat RL 70).



The present full supply level (i.e. top water level) of the existing dam is RL61.5m which is7 metres below the embankment wave wall crest level (i.e. the top of the wave wall on thedam crest). At full supply level of 70.0m, the storage and associated flood surcharge doesnot inundate private property and the required height of embankment sits well in thetopography.

Further details on the works required are provided in Chapter 2 .

Figure 1.1 LOCALITY PLAN AND PROJECT SITE(SOURCE NSW DEPARTMENT OF LANDS SIX VIEWER © six.maps.nsw.gov.au)

1.2 PURPOSE OF REPORT

As part of the dam raising options investigations, an assessment of issues and constraintsfor the preferred raising option is required. Flora and fauna issues need to be consideredas part of the issues and constraints assessment. The purpose of this report is to:



Describe the flora and fauna within the area of the Clarrie Hall Dam that could beimpacted by the preferred raising option;

Identify potential impacts that the preferred raising option would have uponflora and fauna; and

Provide recommendations for the scope of further investigations that would berequired as part of future environmental impact assessment work.

1.3 SCOPE OF WORKS

This preliminary assessment is to consider both terrestrial and aquatic flora and faunaimpacts and is to cover the following items;

Construction impacts, which would be focussed predominately around the Damwall and new spillway channel.

Operation impacts due to permanent upstream inundation and flood inundation.

Detailed tasks to be undertaken include:

A database search of the NSW Wildlife Atlas database to identify recorded floraand fauna species (and any other relevant databases);

Review of aerial photographs, vegetation plans (or similar) and other backgroundinformation applicable to the region;

Reconnaissance investigation to gain an appreciation of the general area and toassist with identifying potentially sensitive areas;

Description of the general ecological character of the area including a review ofthe conservation significance of known (terrestrial, riparian and aquatic) flora,fauna and vegetation communities;

Identification and mapping of ecologically sensitive areas that could be impactedby the preferred option;

Provision of an overview of the likely ecological issues associated with both theconstruction and operation of the proposal;

Provision of recommendations on the extent of any detailed flora and faunasurveys which may be required; and

Documentation of the findings in an overview report.



1.4 STUDY AREA CHARACTERISTICS

1.4.1 Local Setting

The project site and study area are located in the upper reaches of the Tweed Rivercatchment within the Tweed Shire, 15 kilometres south west of Murwillumbah and withina few kilometres of the small village of Uki (refer to Figure 1.1). The area forms part of theremnant caldera of the Mount Warning shield volcano which consists of three distinctivegeomorphological features, the central elevated massif (Mount Warning), the erosioncaldera and the dissected outer rim. Mt Warning itself is located just to the north west ofthe project site and is visible in photographs provided in Appendix A.

The waters of Clarrie Hall Dam are enclosed largely within steep sided valleys ofDoon Doon Creek and its tributaries. Much of the immediate surrounds of the dam ischaracterised by steep slopes and narrow creek gullies.

Land use in the locality has historically been associated with rural industries, primarilycattle grazing/dairying and timber getting/forestry. These past practices havesubstantially influenced the current landscape and vegetation communities/habitatsoccurring within this landscape. Land uses also affect aquatic systems and an assessmentof waterways within the Tweed Shire in 1999 found that water quality was a primarystress factor for the catchments of Doon Doon Creek (TVMS, 2004).

A number of the forested remnants in the locality are now incorporated into the NationalPark system, including Mt Warning National Park. The national parks/nature reservesare part of a broader network of forested remnants occurring in the area, as shown inFigure 1.2 and Figure 1.3 most of these remnants being associated with steep slopes andridgelines/peaks. The more gentle slopes and narrow floodplains tend to have beencleared extensively for agricultural purposes.



Figure 1.2 TOPOGRAPHICAL FEATURES OF THE STUDY AREA



Figure 1.3 SATELLITE IMAGE OF THE EXISTING DAM AND SURROUNDINGFEATURES (SOURCE NSW DEPARTMENT OF LANDS SIX VIEWER ©six.maps.nsw.gov.au)

Currently Clarrie Hall Dam represents the largest freshwater body in the locality and theTweed Shire, other relatively large water bodies in the local area generally beingassociated with coastal wallum systems (e.g Cabarita Lake) or the lower reaches of theTweed River and having saline influences. Small water bodies in the form of farm damsand small billabongs are also scattered through the locality.

The Tweed River is comparatively small in the vicinity of Clarrie Hall Dam and has anumber of small but permanent tributaries, including Doon Doon Creek, Rowlands Creekand Perch Creek (refer to Figure 1.2). Within these upper reaches of the Tweed River,riverine ecology is strongly influenced by exotic and invasive plant species includingSmall-leaved Privet, Large-leaved Privet, Camphor Laurel, Cats Claw Vine and a numberof other vine and grass species (Tweed Shire Council, 2006).



1.4.2 Regional Setting

The Clarrie Hall Dam study area and locality are part of the North Coast bioregion whichis a region of very high biodiversity at both a national and international level(Tweed Shire Council 2006). The ecological status of the great majority of the TweedShires bushland is classified as high or very high with 31 % of the area classified as beinghighly sensitive in the Tweed Vegetation Management Strategy (Kingston, Turnbull andHall 2004). As defined in Volume 2 of the Strategy, the model used for determining statusdelineates as follows:

Four major categories of Ecological Status. The major difference between categories is one of degree.In general the first category (Very High) identifies areas with special ecological values. Thisincludes areas which are either very poorly conserved or highly depleted as well as old growthforest, or significant ecosystems such as riparian areas and wetlands above certain area thresholds.The second category (High) also picks up areas with special ecological values (albeit at lower levelsthan Very High; eg poorly conserved vegetation communities) but also captures a number ofattributes primarily related to ecological function and viability. This latter group includes largetracts of forest, regionally significant corridors, and numerous types of key fauna habitat.

The biological richness of the Tweed Shire is at least partially related to the high diversityof ecosystem types, the development of which is enhanced by a wide range of landformsand geomorphological features. The shire also falls within the region defined by Burbidge(1960) as the Mcleay-McPherson overlap, a zone where temperate and subtropicalbiogeographic provinces meet. Consequently the region hosts a number of species at theirsouthern or northern distribution limits.

A wide range of vegetation communities occur within the local area, includingrepresentatives of dry forest, wet sclerophyll forest subtropical and warm temperaterainforest Both temperate and tropical species are represented in the region, many ofthese species being at the limit of their range (McDonald and Elsol 1984). Although muchof the regional landscape and original vegetation cover is somewhat fragmented, the areastill supports important remnant vegetation and regional wildlife corridors.

Aquatic systems within the region are also high in biodiversity with reportedly a highernumber of fish species occurring than in Kakadu and similar numbers generally to the wettropics (Australian Nature Conservation Agencies State of the Environment Report 1996).

1.5 DOCUMENT REVIEW

A number of documents and plans have been reviewed as part of the flora and faunaassessment process, primary review documents including:

Environmental Impact Statement- Tweed District Water Supply HeadworksAugmentation (Department of Public Works NSW 1980);

Clarrie Hall Dam Catchment Management Plan ( Department of Public WorksNSW 1980);



Fauna and Flora Survey for the proposed Dam on Doon Doon Creek(Parker, 1979);

Tweed Shire Vegetation Management Strategy (2004);

Tweed Shire Council State of the Environment Report 2006;

Clarrie Hall Dam Determination of Optimum Size and Dam Raising OptionsStudy Advanced Report (Draft) (Department of Commerce 2007);

Extracts from Site Confirmation and Selection of Dam Type (Department of PublicWorks 1978); and

Extracts from Report on Tweed District Water Supply (Department of PublicWorks 1980).

Not all documents relevant to the project site could be obtained for review, suchdocuments including the Aquatic Survey for the proposed Dam on Doon Doon Creek(Fisheries, 1978).

1.6 REPORT STRUCTURE

On the basis that this document is primarily to function as a summary or overview report,the report has been structured as follows:

Chapter 1 Provides background information on the existing facility, projectproposal, general locality/region and terminology used throughout thereport;

Chapter 2 Outlines the potential issues and impacts associated with the proposedproject;

Chapter 3 Provides details on specific methodology used for the variousassessments and site inspections;

Chapter 4 Provides details on the results of the studies and assessments andprovides an overview of the site values in terms of flora, fauna andaquatic ecosystems;

Chapter 5 Identifies key issues and constraints associated with the development ofthe project;

Chapter 6 Presents the conclusions on the extent of issues and constraints on theproject and provides recommendations on further survey work requiredto address the key issues.



1.7 TERMINOLOGY

The following terms and abbreviations are used consistently throughout this document:

Billabong A backwater channel, often formed by a cut-off river bend, that forms alagoon or pool when river levels fall.

Biodiversity (biological diversity) The variety of all life forms, comprising geneticdiversity (within species), species diversity and ecosystem diversity;

Buffer Zone considered for the purposes of this study generally to comprise the areaadjoining the existing dam water body and contained within the catchment of the existingdam

Catchment: The area of land drained by a river and its tributaries;

DECC Department of Environment and Climate Change

Development As defined in the EP&A Act;

Ecosystem Any system in which living organisms and their immediate physical,chemical and biological environment are interactive and interdependent. Examples areponds, forests and wetlands;

Environmental flow Flows, or characteristics of the flow pattern, that are eitherprotected or created for an environmental purpose;

Environmental impact statement a document which describes a proposeddevelopment or activity, predicts the possible or certain effects of the activity on theenvironment, and outlines safeguards to mitigate or control environmentally damagingeffects;

EPBC Act Environmental Protection and Biodiversity Act (1999);

Fish ladder or fishway A structure designed to enable fish to move over a physicalbarrier (dam or weir in a waterway);

Flood channel A natural channel in a floodplain, which carries flowing water onlyduring a flood;

Floods Flows that are high enough at their peak to overrun river banks or cause flowthrough high-level anabranches, floodrunners or to wetlands;

Flow regime The pattern of flow in a river which can be described in terms of quantity,frequency, duration and seasonal nature of water flows;

FSL Full supply level;

Habitat The type of environment in which a given animal or plant lives andgrows, including physical and biological conditions;



Local Area Generally equivalent to the Area covered by Tweed Shire

Locality Area within a 20km radius of the project site;

Macrophyte A plant large enough to be seen without the aid of a microscope;

Natural flow regime The likely pattern of flow before European settlement inAustralia. In these guidelines, natural flow regime refers to the flow patterns without anyregulation or extraction of water;

Nutrients Nutritional substances. Unnaturally high levels of nutrients, such as in arivere below a sewage treatment plant, can encourage abnormally fast and prolific growthof algae in the water , or weed growth in the bush;

Preferred option The concept of raising the water level of Clarrie Hall Dam by 10m;

Project Site Clarrie Hall Dam, area subject to future inundation, area subject tospillway construction and one km downstream from dam and current buffer zoneassociated with these areas;

Region North Coast biogeographic region;

Riparian zone The area along the bank of a river or a stream, which often has water-dependent vegetation;

State Environmental Planning Policy (SEPP) 14 NSW Government policy toensure that the coastal wetlands are preserved and protected; prepared under theEnvironmental Planning and Assessment Act 1979;

Stratification Distinct layers of water in a dam or weir pool, formed when there is littlemovement to cause intermixing – usually in summer when deeper layers of water becomecold and deoxygenated. These changes may, in turn, induce other water quality changes.;

Study area The area surrounding the subject site that could be potentially impactedby the raising of the water levels, including areas downstream from the Clarrie Hall Damthat could be impacted by changes in flow regimes;

Tributary A river or creek that flows into a larger river;

TSC Act Threatened Species Conservation Act (1995).

Threatened Species Those species listed as threatened under the EPBC Act, the TSCAct and Fisheries Management Act 1994 (FM Act);

Wetland Land inundated with temporary or permanent water that is usually slowmoving or stationary, shallow, can be fresh, brackish or saline, and where the inundationaffects the plant and animal communities and the type and productivity of soil.



Chapter 2.

2 Project Outline and PotentialImpacts and Issues

2.1 DESCRIPTION OF PROPOSED WORKS ASSOCIATED WITH RAISING THEDAM

The following information has been summarised from information provided by theDepartment of Commerce and in particular from the Draft Options Report (Departmentof Commerce 2007).

Suitable options for raising Clarrie Hall Dam have been developed based on a desktopstudy, review of previous investigations and reports, available survey data from theprevious feasibility investigations and 1/25,000 topographic mapping. The finalassessment of options will take into account engineering, social and environmental factors,as well as efficiency, constructability and economy. Preliminary hydraulic and structuraldesigns have been carried out to confirm the options' layout and dimensions.

The current full supply level (FSL) of the dam is at RL61.5m with a storage capacity of16,000ML. It was subsequently determined that the dam’s maximum optimum size waswith FSL at RL70.0m and storage capacity of about 42,300ML. A number of dam raisingoptions were short listed for further investigation as follows:

a) single stage construction to FSL at RL70.0m,

b) single stage construction to FSL at RL67.5m,

c) single stage construction to FSL at RL64.5m,

d) two stage construction, to FSL at RL67.5m and then from FSL at RL67.5m to FSL atRL70.0m, and

e) two stage construction, to FSL at RL64.5m and then from FSL at RL64.5m to FSL atRL70.0m.

All of the dam raising options have been developed to pass the Probable Maximum Floodlevel. A short list of options has been selected for further development and costing. Fulldetails of all options considered are provided in the Draft Options Report (Dpt ofCommerce 2007).

For all spillway options, a fully concrete lined channel is proposed due to the highlyfractured nature of the rock. Although the excavations will be in hard rock, previousinvestigations indicate close joint spacings and pockets of weak and fractured rock. The



existing spillway was fully lined for this reason. For all spillway options, the concretelining is anchored to the rock and a flip bucket is proposed at the downstream end. Moredetailed hydraulic analysis will confirm the spillway profile and dimensions.

For all dam raising options, the existing intake tower also needs to be raised, this beingmuch simpler and more cost-effective procedure than constructing a new second intaketower A. To provide for adequate earthquake resistance, it is proposed to raise andstrengthen the existing tower structure by providing post-tensioned anchors. Theseanchors are stressed from the tower deck. For the purposes of this study, the provision ofsix stressed anchors have been assumed. Once the existing tower has been raised, theaccess bridge is to be reconstructed on higher piers.

2.2 POTENTIAL IMPACTS RELATING TO FLORA, FAUNA AND AQUATIC

ECOSYSTEM

As mentioned previously, raising the dam level to FSL70.0m provides Clarrie Hall Dam’smaximum optimum size. The total estimated area of inundation 9existing and new) ispredicted to be 400 ha (full supply level) and a total of 500 ha under the flood inundationscenario. The size of the existing water body was predicted to be approximately 220 ha atfull supply level (Department of Public Works 1980).

A number of impacts, either direct or indirect, could be anticipated as a result of theproject development, either during the construction and/or the operation phase asoutlined below. The proposed extent of the new water levels are shown in Figure 2.1

2.2.1 Construction Phase

Potential impacts associated with the construction phase of the project include:

Short term removal of aquatic plant species;

Eutrophication of the existing dam water body through impact on existing aquaticplants and subsequent decay of substantial amounts of plant material;

Adverse impacts on aquatic systems downstream from the spillway throughsedimentation and or alteration of flow regimes;

Exacerbation of existing water weed problems.

Clearing of vegetation and habitats within the proposed new dam level andparticularly within the spillway construction footprint;

Disturbance/modification to vegetation/habitat adjoining construction footprint;

Removal/modification of areas of significant vegetation types;

Removal of threatened plant species;



Removal of potential or likely habitat for threatened species;

Modification to existing wetland habitat through modifications to dam levelsduring construction;

Modification to existing aquatic systems through modifications to dam levelsduring construction; and

Increased risk of introducing/spreading additional exotic plant species byconstruction machinery and vehicles.

Single stage dam raising (options a, b, and c in Section 2.1) has less impact in general onthe surrounding environment and constructability of the works. Staged constructionrequires additional demolition and reconstruction of dam structures, including thespillway, embankment intake tower and access bridge as well as re-establishment anddisestablishment of Contractor’s works. Normal operation of the dam is also disruptedfurther by staged dam raising and there is the additional requirement for lowering thedam storage during construction of the staged works.

2.2.2 Operations Phase

Potential impacts associated with the operations phase of the project include:

Modification to existing aquatic systems within the existing dam from increasedwater levels, increased depth and/or increased potential for greater fluctuation inwater levels;

Short term removal of aquatic plant species from within the existing dam;;

Long term removal of/modification to aquatic plant species and assemblageswithin the existing dam;with the potential for eutrophication of the water bodyfrom decaying plant material;

Long term modification to aquatic fauna species populations within the existingdam from increased water depth;

Long term modification to aquatic systems downstream through alteration of flowregimes and/or flow releases taken from a deeper water depth;

Long term modification to aquatic systems downstream through possiblereduction in larger scouring flows;

Long term modification to aquatic systems downstream through changes in waterquality associated with releases from a deeper storage;

Modification of upstream fish migration patterns associated with water releaseregimes;



Potential improved fish migration upstream from the inundation as a result ofincreased area of inundation and associated removal of some obstacles;

Long term inundation of vegetation and habitats within the proposed new damlevel;

Long term inundation of areas of significant vegetation types;

Long term inundation of threatened plant species;

Long term inundation of potential or likely habitat for threatened species; and

Potentially rapid removal or modification of existing wetland habitat;



Figure 2.1 PROPOSED INUNDATION AREA (MAP PROVIDED BY DOC)



2.3 POTENTIAL ISSUES RELATING TO FLORA, FAUNA AND AQUATIC SYSTEM

There are a number of potential issues associated with the proposed dam raising worksand relating to flora, fauna and aquatic ecosystems. These include:

Known or likely occurrence of threatened species within habitats likely to beremoved/modified;

Modification or loss of existing corridor values with modification/loss of somespecific habitat types (e.g rainforest);

Long term modification to the existing aquatic ecosystem and potential short termloss of high value habitat;

Eutrophication of the existing water body;

Off-site impacts affecting downstream habitats; and

Increased risks to threatened species/habitats associated with increaseddisturbance to the project site.

2.4 KEY THREATENING PROCESSES IN NSW

The following are examples of key threatening processes (KTP’s) listed under the TSC Act(1995) that are relevant or potentially relevant to the project:

1. Alteration to the natural flow regimes of rivers, streams, floodplains andwetlands;

2. Bushrock removal;

3. Clearing of native vegetation;

4. Ecological consequences of high frequency fires;

5. Human-caused climate change;

6. Infection of frogs by amphibian chytrid causing the disease chytridiomycosis;

7. Invasion of native plant communities by exotic perennial grasses;

8. Predation by the plague minnow (Gambusia holbrooki); and

9. Removal of dead wood and dead trees.

Any proposed raising of the level of the storage will require inundation of a broader areaaround the current storage. As such this would include inundation of areas of forest,existing wetlands and other habitats and so would entail the exacerbation of the



aforementioned KTPs. Flooding of additional areas around the dam may entail 6, 7, & 8.The need to clear in the new FSL, would need to be reviewed based on accessibility,clearing techniques and potential water quality impacts from inundation of vegetation.

The future larger body of water may have a slightly different microclimate to that whichcurrently occurs. Such potential modifications to the microclimate need to be considered,as would any implications for green house impacts (additional clearing would result inincreased emissions of greenhouse gases while cleared or inundated vegetationdecomposes.

Clearing of native vegetation is often required prior to inundation because otherwise,rotting vegetation can foul the waters of a storage. If active clearing is required, then thiswould entail KTPs 2, 3, 9 and 10.

There is a formal requirement to assess the implications of any KTPs for threatenedspecies. Such potential impacts are discussed in the following chapters.



Chapter 3.

3 Methodology

3.1 DESKTOP ASSESSMENTS

Prior to visiting the site, preliminary desktop assessments and background research wereundertaken, comprising the following tasks:

Obtaining database records for threatened flora and fauna species from theDepartment of Environment and Climate Change and preparing maps of theserecords within a 5 km, 10 km and 20 km radius from the project site;

Checking the proximity to the project site/study area of recorded occurrences ofthreatened species;

Researching background information on threatened species known to occur in thelocality and the habitats of such species;

Reviewing available information relating to the flora. fauna and aquaticcomponents from previous studies of the study area and project site; and

Studying and comparing available maps and photographs of the project site,study area and locality.

In addition, some time was spent perusing Council databases and mapping programmes,with the assistance of a Council officer, to examine such aspects as areas of sensitivehabitat and wildlife corridors in relation to the study area.

3.2 SITE INSPECTIONS

A site inspection of the existing dam facility, surrounding study area and general locality,was conducted over a two day period on the 11th and 12t h of September 2007. Theinspection was undertaken by Alison Martin from Greenloaning Biostudies and Dr DavidRobertson from Cumberland Ecology. The majority of the inspection was carried out inthe company of Council officers.

Initial inspections were conducted from a small boat, traversing the full length of theexisting dam water body and slightly upstream, as well as entering and inspecting asmany navigable side channels as possible. A brief foot traverse was also made at thefurthest point upstream after gaining access by boat.

Subsequent inspections were undertaken from a vehicle or on foot, the formerconcentrating on accessing the northern and western sides of the dam or dam buffer zone



from existing roads and tracks. Access to the south eastern side of the dam was gained onfoot under the guide of a Council officer.

Data collected during the site inspections was restricted to the following:

Notes on general habitat types occurring at various locations;

Locations of main habitats, including areas of wetland vegetation on the damedges, marked on a 1:25000 topographical map;

Any specific observations of flora and fauna and particularly observations andlocations of threatened species; and

Photographs of representative or significant areas/habitats occurring along thedam edges and surface, such as pockets of rainforest, concentrations of Koala foodtrees, patches of water lilies or stands of dead timber within the water body thatwould provide habitat for fish and for roosting birds.

During the site inspections, discussions were also held with both the Council officers andlocal landholders regarding known environmental conditions of the existing dam andstudy area, current and past land uses, recent fires and known occurrences of flora andfauna.

3.3 RISK ASSESSMENTS

Potential impacts on flora, fauna and aquatic species associated with the project have beenlisted in Section 2.2 of this document and an assessment of the likelihood andconsequence of each impact was then carried out, following standard risk assessmentcriteria (AS /NZS -4360:1999).

The assessments of likelihood of occurrence of an impact (refer to Chapter 5b) are basedon the following:

Information provided by the Department of Commerce;

Discussions with Council officers;

Experience of the Consultants with other water facility projects, in particularShannon Creek Water Storage near Grafton;

Experience of the Consultants with major construction projects; and

Observations made during the site inspections.





Chapter 4.

4 Study Results

4.1 GENERAL ECOLOGICAL ATTRIBUTES OF THE STUDY AREA

All available information indicates that the locality has high biodiversity and alsosupports a high number of terrestrial threatened flora and fauna species, a small numberof these also being water dependent species.

Currently the waters of the dam cover approximately 220 ha and comprise a central openwater body with numerous small side arms associated with small gullies entering theoriginal main drainage line of Doon Doon Creek. These side arms are most numerous inthe central sector of the dam and support some wetland habitats and substantial stands ofdead trees (stags) in a number of areas. Photographs provided in Appendix A illustratethese features.

The central and northern portions of the dam are fringed by an almost continuous belt ofvegetation extending through the buffer zone as defined in Section 1.7) and beyond, asindicated in Figure 1.2 and Figure 1.3 and Appendix A. The southern portionencompasses areas of old farmland and has some open grassland, varying amounts ofnatural regeneration and extensive shallow wetlands. These areas are clearly discerniblein Figure 1.2 and Figure 1.3 and examples are also shown in Appendix A.

4.2 AQUATIC ECOSYSTEM

Clarrie Hall Dam is a large freshwater reservoir formed within largely basaltic catchmentareas that supply high nutrient levels. The high nutrient levels of the dam and theabundant shallow areas, particularly on the southern half of the dam have given rise toextensive beds of Water Lilies (Nymphaea spp.) and some reed beds. A survey of theaquatic fauna and fauna of Doon Doon Creek prior to construction of the original damwas conducted by the NSW State Fisheries in June, 1978. Following 1978, the NSW StateFisheries conducted further studies into the aquatic life in the creek including regularsampling of fauna populations (Department of Public Works 1980: 34).

4.2.1 Aquatic Flora

i. Results of Previous Aquatic Fauna Surveys

A list of aquatic vegetation collected and identified in Doon Doon Creek is given inAppendix 5 of the 1980 EIS report (Department of Public Works 1980). The Milfoil, Spike-



Rush Water Primrose, Water Thyme and Ribbon Weed were considered to be importanthabitat for small forage fish. Filamentous algae provided the basis of the diet forFreshwater Mullet and Sea Mullet. Phytoplankton and aquatic plants are the basicprimary producers in a stream and were therefore a very important part of the food chain(Department of Public Works 1980).

ii. Aquatic Flora in Existing Dam Facility

Some sectors of the existing water body, primarily the perimeter of the dam itself orislands within the dam, and the southern end of the dam, support aquatic plant species.These included, at the time of the 2007 site inspection, Water Lilies (Nymphaea sp.),Common Reed (Phragmites australis) and Azolla (Azolla sp).

Exotic plant species also occur and the water weed known as Salvinia (Salvinia molesta) hasbeen an ongoing problem on Clarrie Hall Dam (Tweed Shire Council 2006). This species issubject to specific management procedures and the issues associated with the species arediscussed further in Chapter 5 of this report.

4.2.2 Aquatic Fauna

i. Results of Previous Aquatic Fauna Surveys

The species of fish and other vertebrates found in Doon Doon Creek and their relativeabundance, as observed by the limited sampling conducted in 1978, are provided inAppendix 3 of Part E of the EIS (Department of Public Works 1980). Extensive fishpopulations existed in the creek. The most notable fish of recreational significance werethe Australian Bass, the Freshwater Catfish, the Sea Mullet and the Freshwater Mullet. Ofthese species the Bass and the Sea Mullet have migratory habitats and make their wayback to the estuary to spawn (Department of Public Works 1980).

Several Platypus (Ornithorhynchus anatinus) were also sighted during the course of theprevious survey of Doon Doon Creek. They were reported as having been relativelycommon to the area. A total of 49 invertebrate fauna species were recorded by the survey,however this was considered a poor indication of the total number due to seasonal factors.

ii. Aquatic Fauna in Existing Dam Facility

The waters of the reservoir are known to support a broad assemblage of fish species.Amongst the fishes, Australian Bass (Maquaaria novemaculeata), are the most sought afterspecies by anglers and are regularly stocked in the dam. An annual fishing competition isheld at the dam, run by the Australian Bass Association (Sweetwater Fishing 2007). Otherprominent fish species known to occur in Clarrie Hall Dam comprise Catfish (Tandanustandanus), Firetail Gudgeons (Hypseleotris galii), Gamboozia and Cox's Gudgeon(Gobiomorphus coxii) (A. Moore, pers.comm. Nov. 2007). High value fish habitat hasdeveloped in association with the numerous sheltered channels supporting stands of dead



trees. At this stage it is considered relatively unlikely that any threatened fish speciesoccur in the existing dam but this could not be confirmed without more detailed surveys.

Given the diversity of habitats in the dam and the productivity of the macrophytes thatoccur there, it is probable that a much higher diversity currently exists than was reportedfor the original aquatic system of Doon Doon Creek in the previous investigations.

Observations during the 2007 site inspection also indicated that the continuing occurrenceof water dependent higher vertebrates, such as Platypus and the Water Rat (Hydromyschrysogaster), is likely around the fringes of the existing dam.

4.3 TERRESTRIAL FLORA

i. Results of Previous Flora Surveys

Previous studies for the Clarrie Hall Dam site prior to the construction of the dam (Parkerand Parker 1979) found that, in broad terms, the area surrounding the Clarrie Hall damsupported communities of dry rainforest intermingling with pockets of warm temperate,subtropical rainforest and wet sclerophyll forest. The species present in the narrow gullystrip were generally indicative of warm temperate rainforest with no clear dominance ofone species. Maiden’s Blush (Sloanea australis), Coachwood (Ceratopetalum apetalum), BlackWalnut (Endiandra globosa) and Bolly Gum (Neolitsia dealbata) were common within thisarea with numerous epiphytes and lianas present. Small areas were dominated byBangalow Palms (Archonophoenix cunninghamii ), typifying pockets of subtropicalrainforest. Other areas of subtropical rainforest dominated by Water gum (Tristanialaurina), various Lillypillys (Syzygium species) and Sandpaper fig (Ficus coronata) were alsocommon.

Areas of wet sclerophyll forest were present within the study area and intermingled withthe warm temperate rainforest community. The dominant species in these areas includedBrush Box (Lophphostmon conferta), Turpentine (Syncarpia glomulifera), Red Bloodwood(Corymbia gummifera), Tallowood (Eucalyptus. microcorys) with the occasional Flooded Gum(E. grandis). Less sheltered areas within this community supported a predominance ofSydney Blue Gum (E. saligna).

In addition to these communities, there were areas of pastureland with isolated treesincluding Hoop Pine (Araucaria cunninghamii), Silky Oak (Grivillea robusta) and Maiden’sBlush (Sloanea australis) exhibiting some remnants of dry sclerophyll rainforest.

The specific communities identified as occurring in the study area prior to the Clarrie Halldam construction were:

Warm temperate/submontaine rainforest;

Sub-tropical rainforest;



Wet sclerophyll forest;

Cleared land scattered with trees

Pure stands of River Oak (Casuarina cunninghamiana); and

Dry rainforest community

Broader vegetation mapping conducted within the Tweed Shire (Tweed Shire Council2004) and shown in Figure 4.1 indicates that these communities are characteristic for thelocality.

One significant species, Milletta australis, (now known as Callerya australis), considered atthe time to be rare and endangered and currently listed as “Rare” under ROTAP Code:{3RC -+ (-C - & -Ci NC)}, was also recorded from the rainforest community within thethen proposed inundation area during the previous studies (Parker and Parker 1979).Other ROTAP listed/significant species as documented in the Vegetation ManagementStrategy for the Tweed Shire (Tweed Shire Council 2004), and recorded previously on thesite, are presented in Table 4.1. Two additional species now listed as threatened underthe TSC Act (1995), Durobby (Syzygium moorei) and Sweet Myrtle (Gossia fragrantissima,then recorded as Austromyrtus fragrantissima) were also recorded, the former species beingrecorded within the southern half of the current inundation area (Area 1 of the previousstudy area) and the latter in the area within two kilometres upstream from the dam wall(Area 2 of the previous study area).

ii. Flora Currently Occurring in the Study Area and Locality

Database records indicate that a rich diversity of threatened flora species occur within a 20kilometre radius from Clarrie Hall Dam (refer to Figure 4.2 ). A total of 34 flora speciesare recorded, of which 6 occur within 5 kilometres and an additional 26 within 5-10kilometres. These species are potentially more likely to occur on the project site on thebasis of proximity and are listed in Table 4.1 .

All threatened flora species listed are rainforest species and there are pockets of rainforestoccurring in the study area but the extent of occurrence is very restricted. There remainshowever, some potential for occurrence of one or more threatened species, speciesconsidered more likely to occur, on the basis of proximity of records, habitat preferencesand numbers of records, species most likely to occur being indicated in bold in Table 4.1 .These include the two tree species recorded previously by Parker and Parker (1979) andnow listed as threatened under the TSC Act (1995), Durobby (Syzygium moorei) and SweetMyrtle (Gossia fragrantissima as described above. The latter may still be represented withinthe project site in remnant pockets of rainforest upstream from the dam wall or in similarhabitat immediately downstream. There also remains some possibility of occasionalspecimens of Durobby occurring in the vicinity of the previous record in remnantrainforest pockets in the southern sector of the project site.



Key features of the site vegetation identified during the recent site inspection include:

Primarily healthy vegetation fringing the majority of the existing water body;

The majority of fringing vegetation comprising dry/wet sclerophyll forest types;

Pockets of warm temperate and subtropical rainforest occurring in a few locationsjust above the existing water level;

Large expanses of aquatic vegetation, generally dominated by native water lilies,occurring in many of the shallow edges and inlets of the existing dam; and

The riparian zone downstream from the existing spillway supporting a variablecover of River Oak Forest.

The vegetation mapping conducted within the Tweed Shire (Tweed Shire Council 2004)and shown in Figure 4.1 indicates that a variety of communities still occur within thestudy area, communities occurring including:

Subtropical/warm temperate rainforest;

Brushbox open forest;;

Blackbutt open forest;

Flooded gum open forest; and

Early regrowth rainforest.


Figure 4.1 TWEED SHIRE VEGETATION MAP (SOURCE DEPARTMENT OF ENVIRONMENT AND CLIMATE CHANGE 2007)

Grey Ironbark/WhiteMahogany

Brushbox Open Forest

Blackbutt Open ForestComplex

Tallowwood Open Forest

Lowland Rainforest

Cam

DomFore

Key

phor Laurel

inant Closed-Openst


Figure 4.2 THREATENED FLORA SPECIES WITHIN THE LOCALITY

Figure 4.2



Table 4.1 Threatened/Significant Flora species recorded within 5 and 10 km fromClarrie Hall Dam

SPECIESNUMBER OF

RECORDSSTATUS

Scientific Name Common NameWithin

5kmWithin5-10km

ROTAPCode

EPBCAct

TSCAct

Acacia bakeri Marblewood 5 VArgophyllum nullamense Silverleaf Area 2 (P) 3RC

Austrobuxus swaiii Pink Cherry Area 2 (P) 3RC

Caesalpinaceaeschortechinii

Large Prickle Vine Area 2 (P)

Callerya australis Blunt-leaved nativeWisteria

Area 2 (P) 3RC

Cassia brewsteri Brush Cassia 4 E

Corokia whiteana Corokia 6 V V

Cupaniopsis serrata Smooth Tuckeroo 2 E

Davidsonia jersyana Davidson’s Plum 1 E

Davidsonia johnsonii Smooth Davidson’s

Plum

1 E

Desmodium

acanthocladum

Thorny Pea 3 2 V V

Diploglottis campbellii Small-leaved Tamarind 5 E E

Doryanthes palmeri Giant Spear Lily 3 V

Endiandra globosa Black Walnut Area 1 -2(P)

2RC

Endiandra hayesiii Rusty Rose Walnut 2 16 V V

Endiandra muelleri subsp.bracteata

Green-leaved RoseWalnut

1 2 E

Floydia praealta Ball Nut 2 V V

Fontainea australis Southern Fontainea 1 V V

Gossia fragrantissima Sweet Myrtle Area 2 (P) 1 E E

Grammitis stenophylla Narrow-leaved FingerFern

1 E

Hicksbeachia pinnatifolia Red Boppel Nut 5 V V

Isoglossa eranthemoides Isoglossa 4 E E

Macadamia tetraphylla Rough-shelled Bushnut 1 6 V V



Table 4.1 Threatened/Significant Flora species recorded within 5 and 10 km fromClarrie Hall Dam

SPECIESNUMBER OF

RECORDSSTATUS

Scientific Name Common NameWithin

5kmWithin5-10km

ROTAPCode

EPBCAct

TSCAct

Oberonia complanata Yellow-flowered King ofthe Fairies

1 E

Ochrosia moorei Southern Ochrosia 5 E E

Owenia cepiodora Onion Cedar 5 V V

Phyllanthus microcladus Brush Sauropus 2 E

Pomaderris notata McPherson RangePomaderris

1 2 V

Sarcochilus hartmannii Ravine Orchid 6 V V

Senna acclinis Rainforest Cassia 1 E

Sophora fraseri Brush Sophora 1 V V

Symplocos baeuerlenii Small-leavedHazelwood

24 V V

Syzgium hodgkinsoniae Red Lilly-pilly 10 V V

Syzgium moorei Durobby 1 –Area 1

(P)

6 V V

Tinospora tinosporoides Arrow-head Vine 1 V V

Uromyrtus australis Peach Myrtle 5 E E

Ziera adenodonta Wollumbin Zieria 2 E E

P Recorded previously in study area by Parker and Parker (1979)

Area 1 – study area for previous flora/fauna surveys extending from approximately twokilometres upstream from the vicinity of the current dam wall to approximately fivekilometres upstream from the dam wall

Area 2 – study area for previous flora/fauna surveys extending from the vicinity of thecurrent dam wall to approximately two kilometres upstream

Species in BOLD TYPE are considered, on a preliminary assessment basis, most likely tooccur within the project site based on records for the locality and habitat requirements

ROTAP Codes taken from Appendix 8 (Tweed Vegetation Management Strategy, 2004)


Table 4.2 Threatened Fauna species recorded within 5 and 10 km from Clarrie Hall Dam

Fauna Group Species Number of Records Status

Scientific Name Common Name Within 5km Within 5-10km EPBC Act TSC Act

BIRDS Amaurornis olivaceus Bush Hen 1 V

Botaurus poiciloptilus Australasian Bittern 1 V

Calyptorhynchus lathamii Glossy Black Cockatoo 1 4 V

Coracina lineata Barred Cuckoo-shrike 3 V

Cyclopsitta diophthalma coxeni Double-eyed Fig-Parrot 2 E E1

Ephippiorhynchus asiaticus Black-necked Stork 1 (on site) E1

Irediparra gallinacea Comb-crested Jacana 2 (on site) * V

Albert’s Lyrebird 26 V

Ninox connivens Barking Owl 1 V

Ninox strenua Powerful Owl 4 V

Oxyura australis Blue-billed Duck 1 V

Pachycephala olivacea Olive Whistler 3 V

Monarcha leucotis White-eared Monach 1 10 V

Podargus ocellatus Marbled Frogmouth 11 V

Ptilinopus magnificus Wompoo Fruit Dove 3 V

Ptilinopus regina Rose-crowned Fruit Dove 2 V

Turnix melanogaster Black-breasted Button-quail 1 V E1

Tyto novaehollandiae Masked Owl 11 V

Tyto tenebricosa Sooty Owl 9 V

BATS Chalinolobus dwyeri Large-eared Pied Bat 1 1 V V

Myotis adversus Large-footed Myotis 1 V

Nyctophilus timoriensis Eastern Long-eared Bat (Southeastern form) 2 V V


Table 4.2 Threatened Fauna species recorded within 5 and 10 km from Clarrie Hall Dam

Fauna Group Species Number of Records Status

Scientific Name Common Name Within 5km Within 5-10km EPBC Act TSC Act

Pteropus alecto Black Flying fox 1 V

Syconycteris australis Common Blossom Bat 1 V

MAMMALS Aepyprymnus rufescens Rufous Bettong 1 V

Dasyurus maculatus Spotted-tailed Quoll 1 V

Macropus parma Parma Wallaby 1 V

Phascolarctus cinereus Koala 10 V

Planigale maculata Common Planigale 1 V

Thylogale stigmatica Red-legged Pademelon 1- Area 1 1 V

AMPHIBIANS Assa darlingtoni Pouched Frog 28 V

Litoria brevipalmata Green-thighed Frog 1 V

Mixophyes iteratus Giant Barred Frog 1 2 E E1

Philoria loveridgei Loveridge’s Frog 4 E1

Numerous records during recent site inspections

P Recorded Previously In Study Area By Parker And Parker (1979)

Area 1 – study area for previous flora/fauna surveys extending from approximately two kilometres upstream from the vicinity of the current dam wall toapproximately five kilometres upstream from the dam wall

Area 2 – study area for previous flora/fauna surveys extending from the vicinity of the current dam wall to approximately two kilometres upstream

Species in BOLD TYPE are considered, on a preliminary assessment basis, most likely to occur within the project site based on records for the locality andhabitat requirements



4.4 TERRESTRIAL FAUNA (INCLUDING WATER-DEPENDENT SPECIES)

i. Results of Previous Fauna Surveys

Previous fauna studies for the Clarrie Hall Dam site prior to the construction of the dam(Parker and Parker 1979) found that the area supported a range of species representativeof the area, none of which were considered threatened at that time. The Red-leggedPademelon (Thylogale stigmatica) however, is now listed as threatened under the TSC Act(1995) and was recorded within the area described as Area 1 (southern sector of currentinundation area).

Small mammals recorded as well as macropods, were considered to be well represented inother areas external to the study area. However, a number of fauna species recorded,including bird species, were rainforest dependent species and these were considered to bemore ‘at risk’ species. Rainforest species were particularly associated with Area 2 –(northern sector of current inundation area).

As the 1979 studies were conducted during the winter months, surveys for reptiles andamphibians was considered to be inadequate to ensure a complete species list wasobtained. There was also considered to be a general paucity of macropods in Area 1,attributed to packs of Beagle Hounds in the district at the time.

ii. Fauna Species and Habitats Currently Occurring in the Study Area

Database records indicate that a rich diversity of threatened flora species occur within a 20kilometre radius from Clarrie Hall Dam (refer to Figure 4.3 ). Given that the majority ofhabitats previously recorded within the study area are still represented to varyingdegrees, based on the current data available, the majority of fauna species recordedpreviously (Parker and Parker 1979) would be expected still to occur. Regeneration of anumber of habitats on the existing dam perimeter has also progressed over the last twodecades and this would be expected to have encouraged some recolonisation by faunaspecies. The existing dam however, inundated the majority of rainforest habitat occurringin the study area and rainforest dependent fauna would therefore be expected to be lessrepresented than previously. Remaining rainforest pockets are however also regeneratingand are likely to provide habitat for some small species, particularly those than also utiliserainforest fringes and adjoining moist forest, or nomadic species such as frugivorousrainforest pigeons. Rainforest frog species that utilise first order streams, such as theGreat Barred Frog (Mixophyes iteratus), could also utilise such habitat where it is associatedwith drainage lines.

Threatened fauna species for the locality are listed in Table 4.2, a total of 36 speciesoccurring within 10 kilometres from the project site. Sixteen of these species are knownfrom within five kilometres from Clarrie Hall Dam and two of these, the Comb-crestedJacana and the Black-necked Stork, are known from the project site and existing damfacility wetlands. The Comb-crested Jacana in particular, appears to be relatively



common, frequenting the extensive Water Lily beds that occur on the existing water body.Numerous individuals of this species were observed during the site inspection inSeptember 2007.

An additional eleven of the threatened species recorded within 10 kilometres from theproject site are considered likely to occur within the project site/study area as indicated bybold type in Table 4.2

The main habitat types currently present within the project site and study area comprise:

Dry sclerophyll forest;

Wet sclerophyll forest;

Rainforest;

Riparian River Oak forest/woodland;

Freshwater wetland with macrophytes;

Open fresh water body; and

Cleared grassland with scattered trees/shrubs.

Key features of the site fauna habitats/species identified during the recent site inspectionsinclude:

Primarily healthy dry/moist sclerophyll forest habitat fringing the majority of theexisting water body;

Areas of potential food trees for threatened species such as the Koala and GlossyBlack Cockatoo;

Pockets of rainforest habitat occurring in a few locations just above the existingwater level, adjoining larger areas of other moist forest habitat;

Large expanses of wetland habitat, supporting extensive Water Lily beds, as wellas some sectors of reeds and other wetland vegetation occurring in many of theshallow edges and inlets of the existing dam; providing feeding/breeding habitatfor species such as waterbirds and amphibians.

Extensive use of the Water Lily beds by the threatened bird species, the Comb-crested Jacana;

Large expanses of open water of variable depths, providing a range of habitatresources for waterbird species and other water dependent species such as theLarge-footed Myotis (Fishing Bat);

Substantial occurrence of stags (dead trees) occurring in sheltered inlets of thedam and offering high value roosting habitat for water birds; and



Sheltered riparian habitat, albeit disturbed with a rocky stream bed and somewater flow downstream from the existing spillway; and

Rainforest/moist habitat associated with first order streams that could providefavourable habitat for threatened frog species such as the Great Barred Frog(Mixophyes iteratus).

4.5 OVERALL ECOLOGICAL VALUES OF THE PROJECT SITE AND STUDY AREA

BIOTA

4.5.1 Aquatic Ecosystem

The construction of a dam, has resulted in a large productive body of water with variableextents of fringing shallows, which in turn has enabled the development of a substantialwetland habitat unique within the locality. The littoral wetlands and the lake waters havesignificant value as a resource, particularly for aquatic species such as water birds,platypus, aquatic macroinvertebrates, frogs, reptiles, snakes and fishes.

The existing dam also has value as fish habitat, providing both ecological and recreationalvalues to the locality. The Bass fishery is a significant and well known resource forrecreational freshwater fishing.

4.5.2 Terrestrial Flora and Fauna

Generally the flora and fauna components of the project site and study area are reasonablyrepresentative of the locality and local area. There are some specific components of thesite that have high value, as indicated in part by the number of threatened species knownor potentially occurring within the study area (refer to Table 4.1 and Table 4.2). This isprimarily reflective of the high value rainforest and wetland habitats, although the overallvalue of the rainforest habitats is likely to be limited because of their current small size.These small rainforest pockets could however, still support specimens of rare/threatenedplant species, particularly considering that such pockets have also apparently undergoneconsiderable regeneration since the dam construction and two threatened tree specimenswere previously recorded (Parker and Parker 1979). A number of the species potentiallyoccurring are also listed under both the TSC Act and the EPBC Act (1999).

The rainforest pockets therefore add to the overall biodiversity value of the project sitethrough both the potential for supporting threatened plant species and as potentialrepresentatives of an Endangered Ecological Community under the TSC Act (1995).Further substantial value is added by the extensive development of freshwater wetlandhabitats, some of which would be likely to conform to the definition of the CoastalFreshwater Wetland EEC.

With regard to fauna, much of the habitat within the study area is likely to be of moderatevalue, taking into account previous levels of disturbance. On the other hand, this value is



likely to be increasing in value over time with the continued natural regeneration ofhabitats surrounding the existing water body.

In addition, the area surrounding Clarrie Hall Dam contains a relatively high number ofthreatened fauna species listed as vulnerable or endangered under the TSC Act (1995). Afew species are also listed under the EPBC Act (1999). A large number of threatened birdspecies have been identified in the surrounding area and include 26 records of Albert’sLyrebird. Both the Black-necked Stork, listed as endangered under the TSC Act and theComb-crested Jacana, listed as vulnerable, have also been recorded on the Clarrie hallDam site. The apparent high value of the site to the latter species adds substantially to theoverall ecological value of the project site and study area. Additional wetland birdspecies, listed as migratory under the EPBC Act, are also considered likely to occur andwould enhance the value of the wetland values.

Mammals listed as vulnerable in the area surrounding Clarrie Hall Dam include theRufous Bettong, Parma Wallaby, Spotted-Tailed Quoll and Koala. The Red-leggedPademelon and Grey Goshawk were also recorded previously (Parker and Parker 1979)and may still occur. Threatened megabat fauna surrounding the Clarrie Hall Dam areaincludes the Common Blossom Bat (Syconycteris australis) and Black Flying Fox(Pteropus alecto), listed as vulnerable under the TSC Act. Amongst the threatenedmicrobats are the Large-footed Myotis (Myotis adversus) and Eastern Long-eared Bat(Nyctophilus timoriensis), the latter species also listed as Vulnerable under the EPBC Act.Both of these microbat species are considered likely to occur on the project site.

A number of threatened amphibians also occur within the area, amongst them the GiantBarred Frog (Mixophyes iterates) and Loveridge’s Frog (Philoria loveridgei) currently bothlisted as Endangered under the TSC Act and the former also listed as Endangered underthe EPBC Act. All threatened species considered potentially or likely to occur within theproject site would be considered as potential subjects species for further more detailedtarget surveys prior to any development of the project.

In summary, the main values identified to date include:

Known occurrence of potential Endangered Ecological Communities (LowlandRainforest and Coastal Freshwater Wetland);

Known occurrence of potential habitat for threatened flora species;

Known occurrence of threatened fauna species (the Comb-crested Jacana andBlack-necked Stork;

Likely site dependency of one threatened fauna species (the Comb-crested Jacana);

Known occurrence of potential habitat for threatened fauna species (such as theKoala);

Likely occurrence of potential habitat for threatened frog species; and



Extensive occurrence of freshwater wetland habitat for waterbirds, includingpotential habitat fro a number of species listed as migratory under the EPBC Act(1999).

4.5.3 Corridor and Vegetation Network Values

In addition, the study area forms part of a sub-regional corridor (shown in Figure 1.4) thatconnects the study area and environs with other similar and /or larger expanses of habitatand provides connectivity with such habitat for fauna species and seed dispersal. Thestudy area also falls within the Border Ranges Hotspot Biodiversity Management Planstudy area. The rainforest communities within this area are identified as a component ofthe Australian Government’s Border Ranges North and South biodiversity hotspot, andare known to supports 97 rainforest plants and 31 animals and to include representativesof two ecological communities currently listed as threatened at either the National or Statelevel (DEC 2006a). The Management Plan aims to provide for the future conservation ofthe exceptional natural environment within the Border Ranges study area. This will beachieved in part by maintaining and improving the connectivity and integrity of species’habitats and communities. Small pockets of rainforest and adjoining moist forests in theClarrie Hall Dam study area therefore have value as an integral part of this Border Rangesrainforest management area.


Figure 4.3 THREATENED FAUNA SPECIES WITHIN THE LOCALITY

Figure 4.3



Chapter 5.

5 Identification of Issues andConstraints

5.1 RISK ASSESSMENT FOR POTENTIAL IMPACTS ARISING FROM THEPROPOSED WORKS

Potential impacts on flora, fauna and aquatic species associated with the project have beenlisted in Section 2.2 of this document. These impacts, for both the construction andoperations phases of the project, are duplicated in Table 5.1 and an assessment of thelikelihood and consequence of each impact forms the basis for a risk assessment asdescribed in Section 3.3.

It should be noted that the assessment for likelihood of occurrence and consequenceassumes that clearing of vegetation within the expanded inundation area may not occurduring the construction phase, unlike what would be expected with most constructionprojects. The steepness of the terrain and lack of access to most of the existing dam’sperimeter are limiting factors to clearing procedures that would be expected to involveheavy machinery. Hand clearing similarly would require machinery access to removefelled timber. It is therefore assumed that clearing around most of the perimeter may notoccur but as the dam fills to the new level during the operations phase, vegetation belowthis level would be inundated. However despite the access limitations it is noted that theneed for vegetation clearing in the new FSL will need to be reviewed by Council, as ifclearing does not occur then this could lead to water quality issues with new areas ofvegetation being inundated. The main impacts on vegetation communities and faunahabitats are therefore expected to occur during the operations phase of the project.

On the basis of the risk assessment and additional information on specific flora, fauna oraquatic components known or considered likely to occur in the study area anddocumented in Chapter 4, key issues and potential constraints for the project arediscussed in Section 5.2.



Table 5.1 Risk Assessment for Potential Impacts

Type of Impact Likelihood Consequence Risk Level

Construction Phase

Clearing of vegetation and habitats, particularly within the spillway construction footprint; A C 3

Disturbance/modification to vegetation/habitat adjoining construction footprint B C 3

Removal/modification of areas of significant vegetation types, C C 2

Removal of threatened plant species C A or B * 3-4

Removal of potential or likely habitat for threatened species C B or C * 2-3

Modification to existing wetland habitat through modifications to dam levels during construction B A 4

Modification to existing aquatic systems through modifications to dam levels during construction B B 3

Short term removal of aquatic plant species B A 4

Adverse impacts on aquatic systems downstream from the spillway through sedimentation and or alteration of flowregimes

C C 2

Increased risk of introducing/spreading additional exotic plant species by construction machinery and vehicles B B 3

Operations Phase

Long term inundation of vegetation and habitats within the proposed new dam level A C 3

Long term inundation of areas of significant vegetation types A B 4

Long term inundation of threatened plant species C A or B * 3-4

Long term inundation of potential or likely habitat for threatened species B B or C * 3

Potentially rapid removal or modification of existing wetland habitat A A 4

Modification to existing aquatic systems A B 4

Short term loss of aquatic plant species; A B 4

Long term loss of/modification to aquatic plant species A A 4

Long term modification to aquatic systems downstream through alteration of flow regimes C C 2

Notes: *.Dependent on specific species and extent of occurrence in locality/region



Likelihood A Almost certain B Likely C Unlikely (or Possible) D Rare

Consequence A Major B Moderate C Minor D Insignificant

Risk Level 1 Low risk 2 Moderate risk 3 High risk 4 Extreme risk



As can be seen from examination of Table 5.1, a number of the impact risks are rated asextreme (risk level 4) or high (risk level 3) and these risk levels would trigger closescrutiny regarding the type and extent of impact involved and would be expected towarrant further studies.

5.2 KEY ISSUES AND CONSTRAINTS

5.2.1 Key Issues Identified

Although the actual amount of land likely to be inundated as a result of the proposed damraising process would be relatively small, there are a number of issues relating to the sitebiota (flora, fauna and aquatic ecosystem) that can be identified that need to be addressed.Some of these issues have been identified by the risk assessment process outlined inSection 5.1 and relate primarily to likely/potential direct impacts on threatened species orthreatened species habitat or on important components of the aquatic ecosystem. Otherissues are related more to gaps in knowledge or information and need to be resolved toallow appropriate final assessments of impact and the development of effectivemanagement procedures.

Key issues identified to date comprise:

Lack of recently-collected information on the aquatic biota currently occurring inDoon Doon Creek downstream from the existing dam facility and unknownextent of impacts;

Requirements for environmental flows necessary to sustain the Tweed Riversystem downstream from the dam (it is understood that studies on this aspect arecurrently being conducted by Dr Keith Bishop);

Lack of information on the aquatic biota currently occurring in the existing damfacility and unknown extent of impacts;

The potential occurrence of threatened plant species in remaining pockets ofrainforest within the proposed inundation zone and unknown extent of impact onsuch species or their habitat;

The known occurrence and expected direct impact on at least two potential EEC’s(Lowland Rainforest and Freshwater Wetland) and unknown extent of suchimpact;

The known occurrence, site dependence and expected direct impact on at leastone threatened fauna species (the Comb-crested Jacana) and unknown extent ofsuch impact;



The known or potential occurrence and potential direct impact on otherthreatened fauna species (such as the Black-necked Stork) or migratory speciesand unknown extent of such impact; and

Discrepancies in mapping of RL 70, limiting the definition of the inundation areaon both available maps of the project site and on the ground and also limitingassessments of areas likely to function as offsets for wetland to be modified.

The extensive and ongoing occurrence of the exotic water weed Salvinia on the existingwater body of the dam has necessitated regular non-chemical management of infestationsusing containment booms, mechanical removal and biological control (Tweed ShireCouncil 2006). Continuing weed control would therefore also be an issue to address toensure appropriate management is continued.

5.2.2 Constraints to Project

There are a number of constraints or potentially significant issues that need to beinvestigated further. These include requirements for downstream flows within the TweedRiver system, potential impacts to threatened flora and fauna that are listed by the TSCAct and/or EPBC Act and requirements for the provision of compensatory habitat.Information required to determine the extent of such impacts is currently not available,including the clear definition of the area to be impacted. A preliminary map of potentialconstraints, focusing on areas of high value such as wetlands or rainforest pockets and/orareas subject to impacts from changes to flow regimes, is provided in Figure 5.1.

Aquatic ecosystems within the dam are likely to benefit in the medium to long termbecause the dam size will increase and the current expanses of aquatic macrophytes thatform fringing littoral communities in many areas are likely to re-establish along the futurestorage water line. Notwithstanding that, in the short term, there will be disruption toaquatic ecology and it is likely that such littoral communities will take several years to re-establish. In the interim, key species that depend upon them such as fish,macroinvertebrates and waterbirds will be impacted. Some may benefit in the short term,whereas others such as the Comb-crested Jacana, a Vulnerable bird species, may bedisplaced until the lily pads that it depends upon are regenerated.

Where endangered ecological communities or threatened species habitat is to be impactedand lost through inundation, it is likely that there will be a requirement by State and/orCommonwealth agencies to require compensatory packages to be developed. Wherecleared and semi-cleared land is available in the catchment, such compensatory (oroffsetting) packages may entail regenerating or recreating forest habitats over time andpermanently conserving them. Such measures are likely to be particularly relevant forrainforest and other forest communities and species.

Biobanking, under the Threatened Species Conservation Amendment (BiodiversityBanking) Act 2006, is a new concept in NSW and the regulations have not been finalisedyet. However, this may be applicable to the offsetting of the terrestrial ecological impactsof the proposed dam raising.

http://www.legislation.nsw.gov.au/sessionalview/sessional/TITLE/Threatened Species Conservation Amendment (Biodiversity Banking) Act 2006 No 125.pdf




To the extent that the dam raising would necessitate future clearing of native vegetation,permits to clear may be required under the TSC Act and/or EPBC Act. There may also beconstraints placed upon the staging and timing of such clearing.



Figure 5.1 PRELIMINARY POTENTIAL CONSTRAINTS





Chapter 6.

6 Conclusions and Recommendations

6.1 CONCLUSIONS

The construction of the existing Clarrie Hall Dam has resulted in the permanentinundation of some areas of significant vegetation types, particularly rainforestcommunities, and impacted on a small number of threatened flora and fauna speciesand/or their habitats. However, the creation of a large water body and the developmentof substantial areas of freshwater wetland, together with the natural regeneration ofvegetation around the existing dam perimeter, has resulted in a valuable, albeitsubstantially modified, ecological attribute and aquatic system unique to the locality andthe Tweed Shire.

The proposed raising of the dam to RL 70 will result in the additional inundation of somesignificant vegetation communities and fauna habitats and modification of the wetlandhabitats and aquatic system that have developed over the last 25 years. Some adverseimpacts on threatened species and communities likely to conform to EndangeredEcological Communities descriptions (Lowland Rainforest on Floodplain and CoastalFreshwater Wetland on Floodplain) would be expected and impacts on the Comb-crestedJacana in particular would be likely to be significant.

On the basis of currently available data and observations made during site inspectionscarried out by the authors of this report in September 2007, the majority of the issuesidentified are not likely to pose major constraints to the project providing the issues aredealt with appropriately and sufficient information is obtained to allow adequateassessments of potential impacts. Some issues identified however, would be more likelyto pose substantial constraints on the project. These include:

Requirements for downstream flows within the Tweed River system,

The occurrence of any endangered plant species within the rainforestcommunities, particularly if the species is listed under both the TSC Act and theEPBC Act and its local population is not considered secure. A flora survey isrequired as described below;

The occurrence of Endangered Ecological Communities within the proposedinundation area; It is likely however, that the small pockets of rainforest wouldpose a lesser constraint in terms of EEC’s than the much more extensive expansesof freshwater wetland communities;

Threatened fauna occurrence, primarily with a dependence on the project sitehabitats and subject to direct impacts from the proposed dam raising;



Site dependence of wetland bird species listed as migratory under the EPBC Act(1999); and

Requirements for the provision of compensatory habitat.

Although aquatic ecosystems within the dam are likely to benefit in the medium to longterm, in the short term, there will be disruption to aquatic ecology and it is likely thatlittoral communities will take several years to re-establish. In the interim, key species thatdepend upon them such as fish, macroinvertebrates and waterbirds will be impacted.Some may benefit in the short term, whereas others such as the Comb-crested Jacana, aVulnerable bird species, may be displaced until the lily pads that it depends upon areregenerated.

Delineation of potential offsets to the wetland habitat and rainforest likely to be removedand/or modified would lessen the long term impacts and be likely to lessen theconstraints on the project overall.

A significant issue associated with the proposal as it currently stands is a lack of definitiveinformation on the extent of expected inundation on the ground and correspondingdetailed mapping. Such information is a priority to allow subsequent impact assessmentsand offset potentials (such as extent of shallow wetlands to be created) to be determined.

6.2 RECOMMENDATIONS

In order to address the current issues identified for the project and thereby minimisepotential constraints, it is recommended that a number of priority actions be undertaken.These are listed below in order of priority.

6.2.1 Priority 1

As an immediate priority, attention be given to ensuring that the mapping of RL 70 onrelevant data layers held by Council is accurate and clearly shows the expected extent ofimpact when overlain over such layers as vegetation communities.

6.2.2 Priority 2

Ensure that the proposed construction footprint also is accurate when overlain over suchlayers as vegetation communities.

6.2.3 Priority 3

Conduct further surveys and assessments of potential impacts on the following aspects;

Aquatic flora and fauna currently occurring both downstream from and withinthe existing dam and key habitat requirements/existing habitat characteristics



(such as water quality, temperature). These studies would need to considercurrent and likely fish passage patterns;

Definition and mapping of current vegetation communities within the study areaand assessment of EEC status, with particular focus on the area within theproposed inundation area and including a 50-200m perimeter area (this area to bedefined following completion of priority actions 1 and 2 above);

Target searches for threatened flora and fauna species, the final determination ofsubject species to be made following completion of priority actions 1 and 2 aboveand taking the second dot point of action 3 (above) into consideration; and

More detailed assessments and comparisons of the study area components withina local context.

It is also recommended that the feasibility of adding a fish ladder is considered furtherduring subsequent investigations or alternatively investigate offsets for fish passagedownstream.

.It is recommended that further fauna field surveys cover all fauna groups, given theextended time period between the previous surveys and the present. However, it is alsorecommended that survey locations be restricted to the inundation area and immediateperimeter, given that the expected zone of impact will comprise a narrow bandencompassing the existing dam facility, rather that a broad expanse of land acrosssubstantial tracts of the study area.

Surveys should be carefully designed to sample representative habitats as it would belogistically impractical and economically prohibitive to carry out detailed surveys aroundthe entire perimeter. Consideration should also be given to co-ordinating the aquatic andterrestrial surveys as the most practical access for much of the project site would be byboat, vehicle access being very limited and time consuming.

Timing of the surveys also needs to take account of the specific behavioural patterns of thetarget species and to adhere to the draft threatened species survey guidelines (DEC 2004).It is recommended that subsequent target survey design incorporate a final detailedschedule to ensure all target species are sampled at an appropriate time for the species,with as much overlap in survey times as possible to maximise survey efficiency. Twoseasons of surveys would be recommended, likely optimal survey periods being springand late summer/autumn.

A preliminary list of target species would include, but not be restricted to:

Flora

White Lace-flower (Archidendron hendersonii);

Heart-leaved Bonewood (Bosstoa selwyni);

Thorny Pea (Desmodium acanthocladum);



Small-leaved Tamarind (Diploglottis campbellii);

Rusty Rose Walnut (Endianda hayesi);

Green-leaved Rose Walnut (Endiandra muelleri subsp.bracteata);

Sweet Myrtle (Gossia fragrantissima);

Rough-shelled Bush Nut (Macadamia tetraphylla);

Pygmy Bishop’s Hat (Mitrasacme pygmaea);

Onion Cedar (Owenia cepiodorqa); and

Hartman’s Sarcochilus (Sarcochilus hartmannii).

Fauna

Bush Hen (Amauornis olivaceus);

Black-necked Stork (Ephippiorhynchus asiaticus);

Comb-crested Jacana (Irediparra gallinacean);

Glossy Black Cockatoo (Calyptorhymchus lathami);

Double-eyed Fig Parrot (Cyclopsitta diophthalma coxeni);

Alberts Lyrebird (Menura alberti);

White-eared Monarch (Monarcha leucotis);

Blue-billed Duck (Oxyura Australia);

Wompoo Fruit Dove (Ptilinopus magnificus);

Eastern Long-eared Bat (Nyctophilus bifax);

Greater Broad-nosed Bat (Scoteanax rueppelli);

Koala (Phascolarctos cinereus);

Red-legged Pademelon (Thylogae stigmatica);

Green-thighed Frog (Litoria brevipalmata);

Great Barred Frog (Mixophyes iterates); and

Loveridge’s Frog (Philoria loveridgei).



During the final assessment process, it is recommended that substantial attention be givento the potential for both wetland and rainforest community offsets to be developed.Careful consideration of the overall long term management of the study areaenvironment, particularly with regard to fire management, threatened species objectivesand water weed management is also recommended.

Greenloaning Biostudies Pty Ltd Page 1


References

Australian Nature Conservation Agencies. 1996 State of the Environment Report.

Department of Environment and Climate Change NSW. 2007. Border Ranges RainforestBMP Maps. http://www.environment.nsw.gov.au/home.htm. Accessed 27November 2007.

Department of Environment and Conservation 2006a Newsletter # 1 Border RangesBiodiversity Project Notice to Stakeholders 7 April 2006

Department of Environment and Conservation 2006b Newsletter # 2 Border RangesBiodiversity Project Notice to Stakeholders July 2006.

Department of Environment and Conservation 2007 Newsletter # 3 Border RangesBiodiversity Project Notice to Stakeholders June 2007.

Department of Environment and Water Resources. 2007. EPBC Act Protected MattersReport. http://www.environment.gov.au/cgi-bin/erin/ert/ert_dispatch.pl?loc_type=lga&search=Search&report=epbc.Accessed 7/08/2007.

Department of Public Works NSW. 1980. Report on Tweed District Water Supply HeadworksAugmentation Part E. Environmental Impact Statement. Prepared for Tweed ShireCouncil.

Department of Public Works NSW. 1980. Tweed District Water Supply HeadworksAugmentation: C.H. Hall Dam Catchment Management Plan. Prepared for TweedShire Council.

Department of Public Works. 1979. Site Confirmation and Selection of Dam Types . Preparedfor Tweed Shire Council.

Hunter Water Australia. 2006. Tweed IWCM Context Study and Strategy Report Appendix C.Prepared for Tweed Shire Council.

Kingston, W.B., Turnbull, J. W. and Hall P.W 2004. Tweed Vegetation Management Strategy2004. Ecograph Consultants Prepared for Tweed Shire Council.

National Parks and Wildlife Service . 2007. Atlas of NSW Wildlife Search Results.http://wildlifeatlas.nationalparks.nsw.gov.au. /wildlifatlas/watlassSpecies.jsp.Accessed 09/08/2007.

New South Wales Government. 2006. Threatened Species Conservation Amendment(Biodiversity Banking) Act 2006.http://www.legislation.nsw.gov.au/sessionalview/sessional/TITLE/Threatened%20%20Sp

http://www.environment.nsw.gov.au/home.htm

http://www.environment.gov.au/cgi-bin/erin/ert/ert_dispatch.pl?loc_type=lga&search=Search&report=epbc

http://www.environment.gov.au/cgi-bin/erin/ert/ert_dispatch.pl?loc_type=lga&search=Search&report=epbc

http://wildlifeatlas.nationalparks.nsw.gov.au/




Greenloaning Biostudies Pty Ltd Page 2


ecies%20Conservation%20Amendment%20(Biodiversity%20Banking)%20Act%202006%20No%20%20125.pdf. Accessed 10/11/07.

Parker, Peter and Geraldine Parker. 1979 Fauna and Flora Survey for the proposed Dam onDoon Doon Creek. Prepared for Department of Public Works.

PlantNET FloraOnline. 2007. http://plantnet.rbgsyd.nsw.gov.au/search/index.html Accessed10/09/2007.

Sweetwater Fishing 2007 http:/sweetwater fishing.com.au/ClarrieHall.htm Accessed 16/05/07.

The Big Volcano. 2005. Interactive Regional Map. www.bigvolcano.com.au. Accessed16/05/07

Tweed Shire Council. 2006. State of the Environment Report 2006. Prepared for Tweed ShireCouncil.

Tweed Shire Council. 2007. Water Series No 1 Clarrie Hall Dam.http://www.tweed.nsw.gov.au/Education/w_1_clarrie.htm. Accessed16/05/07.

http://www.bigvolcano.com.au/

http://www.tweed.nsw.gov.au/Education/w_1_clarrie.htm

Greenloaning Biostudies Pty Ltd


Appendix A

Photographs

Greenloaning Biostudies Pty Ltd Page A.1


Photograph A.1 Open water body of Clarrie Hall Dam with Mt Warning inbackground, old farmland on right and wetland vegetation onright hand fringe

Photograph A.2 Old farmland in background with dense Water Lily bed inforeground



Photograph A.3 Rainforest pocket on fringes of side arm of the dam

Photograph A.4 Rainforest elements regenerating on dam edges



Photograph A.5 Sheltered side arm of Clarrie Hall Dam with dead trees andwetland vegetation

Photograph A.6 Regenerating rainforest with Bangalow Palms



Photograph A.7 Habitat features with dead standing tress, logs, open water andWater Lily beds

Photograph A.8 Comb-crested Jacana utilising dense Water Lily bed

Documents

PROPOSED RAISING OF CLARRIE HALL DAM FINAL REPORT PROPOSED RAISING OF CLARRIE HALL DAM FINAL REPORT ... Proposed Raising of Clarrie Hall Dam ... A.2 OLD FARMLAND IN BACKGROUND WITH