Reedy Lake – Surface/ Ground Water Interaction Report

G.D. Mockunas Bachelor of Applied Science – Geology (Exploration & Environmental) University of Ballarat School of Science & Engineering Department of Geology 2452507

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION REPORT

Dates: Semester 2 (Teaching Period 3), 2006.

Prepared for Mr. Peter Dahlhaus Senior Lecturer - Geology

University of Ballarat School of Science & Engineering Department of Geology

In conjunction with: CCMA (Corangamite Catchment Management Authority), Geelong Field & Game (FGA), Parks Victoria & CSIRO - Land & Water Division.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION Abstract

This report seeks to investigate the hydrological setting of Reedy Lake and possible influences upon the surface/ groundwater systems, which constitute it. The lake is a diverse freshwater environment forming part of the Lake Connewarre State Gaming Reserve, near Barwon Heads.

Groundwater sampling programs were conducted for major ion and stable isotope analysis, in an attempt to further understanding as to the nature of the surface/ groundwater interactive processes that may be occurring. The analysis suggested that while some degree of interaction was undoubtedly happening across the lake, it was highly variable. Investigation of the differing temperament of the hydrological setting which shapes the lake could not be attuned to any singular process and rather, a multitude of factors were deemed responsible.

Regional and local geological factors including variability in shallow aquifer sedimentary units, where considered to be of particular influence. Surficial processes, such as the influence of the Barwon River, also played a role in shaping the lakes surface and groundwater aquifer systems. Potential factors such as the role of deeper aquifer systems on the lake system and the presence of a saltwater wedge, were also considered. Single bore recovery tests were also conducted in an attempt to further understanding of aquifer characteristics, particularly with regard to hydraulic conductivity values. The tests indicated that hydraulic conductivity values differed across the lake, most probably as a function of lithological/ sedimentary controls.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION Acknowledgements

I would like to extent my thanks to the following people, who helped in the development of this report:

Mr. Peter Dahlhaus (Lecturer/ Supervisor, University of Ballarat), for his assistance in terms of sharing information, general support and enthusiasm in helping me develop the project.

Mr. Ray Agg (Geelong Field & Game Association) for his fantastic assistance, while conducting bore sampling.

Mr. Ian McLachlan (Barwon Water) for his assistance in providing information and a boat, in which to access bores on the lake.

Mr. Bob Smith (Technician, University of Ballarat) for his assistance and sharing of information, which made the field work much more productive.

CCMA (Corangamite Catchment Management Authority) for financial assistance, in field work and sample analysis.

CSIRO Land & Water for there assistance in water analysis of major ions and stable isotopes.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION CONTENTS i. Abstract ii. Acknowledgements iii. List of Figures

1. Introduction……………………………………………… 6

1.1 Aims of Project 6-7 1.1.1 Scope of this report 7 1.2 Study Area 7-8 1.2.1 Land Use 8-9 1.2.2 Climate 9-10 1.2.3 Environmental Values 10-11

2. Research Methods………………………………………. 12

2.1 Previous Work 12-13 2.2 Field Work 13-14 2.2.1 Bore Sampling Overview 14 2.2.2 Bore Sampling Procedures 15-16 2.2.3 Single bore recovery tests 16-18 2.3 Sampling Analysis 18 2.4 Computer Modelling 18-19

3. Geological Setting………………………………………... 19-20

3.1 Geomorphology (Landscape Evolution) 21-22 3.2 Recent Processes 22-23

4. Lake Hydrogeology……………………………………… 24

4.1 Overview 24-25 4.2 Hydrological Observations 25-26 4.2.1 Single Bore Recovery Tests 26-28 4.2.2 Bore Log Analysis 28-30 4.2.3 Bore Characteristics 30-32 4.3 Hydrogeochemistry 32 4.3.1 Major Ion Chemistry 32-40 4.3.2 Stable Isotope Analysis 40-44 4.4 Conceptual hydrological model 45-47

5. Discussion………………………………………………… 48 6. Conclusion……………………………………………….. 49 7. Recommendations for further research………………... 50 8. References ……………………………………………….. 51 9. Appendices……………………………………………….. 52-70

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION LIST OF FIGURES

Figure 1.01 Lake Connewarre State Game Reserve, including the Reedy Lake study area.

Figure 1.02 Average Monthly Rainfall for Geelong

Figure 1.03 Average Monthly Temperature Values for Geelong

Figure 1.04 Extent of reeds Phragmites and Typha across Reedy Lake.

Figure 1.05 Reedy Lake, including surrounding roads and bores.

Figure 1.06 Bore 4 – Hospital Swamp (SE Corner). Typical pump set up (7meter pump)

Figure 1.07 Typical field setup for bore recovery tests. Author is programming the level-logger, ready to put down bore immediately after pumping (Source: Dahlhaus, 2006)

Figure 1.08 Geology of Reedy Lake & Bellarine Peninsula

Figure 1.09 Piper of combined initial/ recent sampling chemistry (May/ August, 2006)

Figure 1.10 Piper diagram of combined surface and groundwater (initial and recent sampling results)

Figure 1.11 Combined surface (Barwon River & Reedy Lake) and groundwater (initial/ recent)

Figure 1.12 Stiff Plots of major ion chemistry of bore water samples (initial/ recent -1.23 – recent samples denoted by ‘R’) and a stiff plot of the lakes surface water and the Barwon River (Sampled by Annette Barton, CSIRO Land & Water, 2006)

Figure 1.24 A Schoeller diagram with the data for both the initial and recent bore sampling chemistry (Recent sampling denoted by letter ‘R’), coupled with Surface Water and Barwon River samples. Source: AquaChem v.3.7

Figure 1.25 Stable isotope data from May/ August sampling, plotted against meteoric water line for Melbourne (adapted from Dahlhaus, 2006)

Figure 1.26 Stable isotope data for both initial/ recent groundwater analysis, coupled with surface water analysis obtained for Reedy Lake and the Barwon River by Annette Barton (CSIRO, 2006; adapted from Dahlhaus, 2006)

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Figure 1.27 3D-conceputal model of Reedy Lake, vertically exaggerated and overlain by Queenscliff 1:250 000 Geological Map

Figure 1.28 Cross-sectional diagram of Reedy Lake, taken from above 3D- conceptual model. Green line represents the normal topographic height across the lake, where the red line illustrates vertically exaggerated section across the lake

Figure 1.29 Airborne Radiometric data. Potassium response (purple) is restricted to regions of topographic lows (Source: Dahlhaus, 2006)

LIST OF TABLES

Table 1.1 Previous studies of Reedy Lake and surrounding region

Table 1.2 Hydraulic Conductivity, as obtained from single bore recovery test analysis.

Table 1.3 Table of major ion chemistry analysis of Reedy Lake, including both groundwater sampling data (May, August; 2006) and surface water chemistry (July, 2006).

Table 1.4 Stable Isotope Analysis data of initial (May) and recent (August) sampling of groundwater, coupled with surface water stable isotope analysis (conducted by Annette Barton, July 2006).

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION 1. Introduction

Reedy Lake has been the subject of particular interest by the Corangamite Catchment Management Authority (CCMA), Parks Victoria, Barwon Water, Geelong Field & Game and the CSIRO. Studies of the lake have been undertaken to develop understanding of the hydrological setting, salinity levels and floral and faunal characteristics of the lake. The five current piezometers installed by the CCMA during the April/ May (2006) period, were designed to further knowledge of the hydrologic system of the lake. This in turn could be used to develop appropriate water management strategies, to maintain the lake vegetation and manage salinity levels.

1.1 Aims of Project

This study entails to develop an understanding of the surface/ groundwater interaction processes, which occur in the region of Reedy Lake. The lake forms part of the wetlands in the lower Barwon River estuarine complex, located in the Lake Connewarre State Game Reserve. A number of studies are currently being undertaken within the reserve, focusing on various aspects of the wetlands. The main objectives of this project are to:

1. Consolidate the known information on groundwater for the Reedy Lake region; 2. Develop the five piezometers (see Figure 1.05) and obtain aquifer parameters (specifically, hydraulic conductivity values) through single bore tests; 3. Sample the groundwater for analysis of major ions and stable isotopes (to be conducted by CSIRO Land & Water, Adelaide); 4. Compare the groundwater samples with the previous results and draw any conclusions regarding any observed changes;

Consolidation of knowledge of the area in terms of geology, geochemistry, geomorphology and geophysics, aims in further develop an understanding the hydrologic setting of Reedy Lake. Similarly the development of the five water

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION monitoring bores aims to build upon current knowledge, through major ion and stable isotope analysis. Additionally, it aims at helping distinguish the surface/ ground water interactions that may be occurring.

1.1.1 Scope of this report

The report was complied using existing published data and collated data, from existing groundwater bores. There are no guarantees as to the accuracy of previous work. All images are that of the author, unless otherwise stated throughout the report. This document was produced in partial fulfilment of the required outcomes of the SX729 Project, constituting part of the Bachelor of Applied Science – Geology coursework, at the University of Ballarat (Third Year). Supervisor: Mr. Peter Dahlhaus, University of Ballarat. Associate Supervisor: Mr. Tony Miner, A.S. Miner Geotechnical.

1.2 Study Area

Reedy Lake is situated south of the city of Geelong, forming part of the lower Barwon esturine complex in the Lake Connewarre State Game Reserve (see Figure 1.01 below). It is located approximately 65km southwest of Melbourne and 10km southeast of Geelong, near the township of Barwon Heads (Stokes, 2002). The state game reserve is managed by Parks Victoria and some private land exists around the outer edges of the lake.

The Lake itself consists of large areas of mudflats (exposed when the lake is dry) and various types of vegetation, particularly salt tolerant varieties. Water levels in the lake are variable, as they are controlled by the diversion of water from the lower Barwon River. The influence of the Barwon River is greater during periods of peak flow and flooding, where water often spills out into the lake system.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Figure 1.01: Lake Connewarre State Game Reserve, including Reedy Lake. Source: Dahlhaus, 2006.

1.2.1 Land Use

The lake system itself forms the Lake Connewarre State Game Reserve and is of major importance, in terms of Victorian wetland systems. The system provides habitat for a variety of native birdlife and migratory bird species, as well as a varying number of indigenous wetland flora species. Stokes (2002) indicates that Lake Connewarre is an important habitat for native fish, with the inlet of the Barwon River providing an excellent spawning ground. Reedy Lake does not share the same indigenous fish life as Lake Connewarre, as the lake is often drained and European carp appear to be the prevailing fish species. The lake is also used intensively for hunting, with limited ability for boating activities.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Local properties surrounding the lake still use there land for grazing cattle, sheep and other livestock. They are fenced off from the lake as grazing in the lake area was stopped, due to potential environmental degradation factors. Denudation of the surrounding landscape due to farming practices, both past and present, may have also had a profound influence on overland flow into the lake system. In recent field work it was observed at the area near Hospital Swamp a number of large trees, probably of the Cyprus variety, had been removed.

1.2.2 Climate

Lake Connewarre Game Reserve and the Bellarine Peninsula experience maritime climatic conditions, which is most probably influenced by its proximal location to the coast. Climate is characterised by warm, dry summers and winter rainfall maximums (Stokes, 2002). Figures 1.02 and 1.03 below are graphs of the Geelong regions monthly rainfall/ temperature averages, sourced from the Australian Bureau of Meteorology.

Figure 1.02: Average Monthly Rainfall for Geelong. Source: www.bom.gov.au, 2006.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Figure1.03: Average Monthly Temperature Values for Geelong. Source: www.bom.gov.au, 2006.

1.2.3 Environmental Values

The lake is of national/ international importance, being listed under the RAMSAR convention on wetlands and has bird species listed under the China-Australia Migratory Bird Agreement (CAMBA) and the equivalent with Japan (JAMBA). The vegetation of Reedy Lake is characteristic of the ground/ surface water systems, which are at work. The lake is believed to have supported a combination of fresh and salt-tolerant plant communities in the past, with vegetation probably influenced by more saline groundwater conditions (Ecological Associates, 2006).

In a historical review of vegetation occurrences at Reedy Lake, Ecological Associates (2006) suggest a number of plant species are indicative of varying salinity conditions within the groundwater. Vegetation which currently predominates around much of the lake area includes Phragmites and Typha (See Figure 1.04 below), which are symptomatic of fresh (shallow) groundwater conditions (Ecological Associates, 2006). Past observations have noted at higher elevations on the perimeter of the lake (at the base of the scarp; 0.5 – 1m AHD), more salt-tolerant herbland species such as Sarcocornia quinqueflora, Scheonoplectus pungens, Lignum and Distischlis

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION distichophylla are present (Ecological Associates, 2006). Ecological Associates (2006) does suggest that Phragmites and Typha also exist at higher elevations (~0.8m AHD) and that they predominate between the natural levee of the Barwon River and the lake (presumably where freshwater recharge from the river would occur).

It is plausible to suggest that vegetation can give a very limited understanding of the shallow groundwater/ surface water processes, occurring across much of the lake. Interpretations of varying vegetation varieties throughout the lake, may give indications as to the varying salinity levels of groundwater in the lake. It raises questions regarding the nature of surface/groundwater processes and the origins of the highly saline groundwater systems, operating in areas of the lake.

Figure 1.04: Extent of reeds Phragmites and Typha across Reedy Lake. Source: Ecological Associates, 2006.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION 2. Research Methods

2.1 Previous Work

The relevant literature published in regards to the Lower Barwon wetlands system and that of Reedy Lake/ Lake Connewarre, was used in the development of this report. Information regarding the specific study area was limited. Coulson (1935) & Rosengren (1973) proved to be excellent resources, in understanding the geology/ geomorphology of the area. Various other reports commissioned by the CCMA which presides over the wetlands area, also proved invaluable resources to draw upon (see Table 1.1 below for a list of previous work utilised in the development of the report).

Geological maps, particularly that of the 1:250,000 Queenscliff Geology sheet provided important information in regards to the local and regional geology. The map also aided in interpretation of the geomorphology of the lake area and the processes which have occurred, to produce the current geological and topographical setting. Air photographs were also coupled with geological maps (using MapInfo v8.0), in order to give better visual interpretation of the lake and its surrounds.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Previous Studies of Particular Importance:

Barton, A., Herczeg, A., Cox, J. & Dahlhaus, P., (2006). Sampling and

analysis of lake in the Corangamite CMA region. Report to the

Corangamite Catchment Management Authority, CCMA Project WLE/42- 009: Client Report 3. Cecil, M.K., Dahlhaus, P.G. & Neilson, J.L., (1988). Lower Barwon – Lake Connewarre Study. Geological Survey Division. Department of

Industry, Technology & Resources.

Coulson, A., (1935). Geological Notes on Lake Connewarre, near

Geelong. Proceedings of the Royal Society of Victoria. Vol. XLVIII (New Series). Part 1. H.J.Green, Government Printer. Melbourne. Australia. Miner, A.S., (2006). Installation Report for Groundwater Wells at Reedy Lake and Hospital Swamps. Report No:337/01/06.

Rosengren, N.J., (1973). Lake Connewarre and the Barwon Estuary.

Department of Geography, University of Melbourne.

Stokes, D., (2002). Tidal Dynamics and Geomorphology of the Lower Barwon Tidal Inlet. Thesis. La Trobe University, Bendigo, Victoria. Australia. Table 1.1: Previous studies of Reedy Lake and surrounding region.

2.2 Field Work

As part of the project four days of field work were undertaken, involving bore development/ sampling, single bore recovery tests and field observation work. Field observations involved day of travelling around the lake region, qualifying what is expressed on the geological and topographic maps, with that of the observed landscape (encompassing the geomorphologic picture of the region). Field work also attempted to try put in a general context the natural and man made processes, which have helped shape the present day system.

The lake is easily accessible and access to the bores is either by road or by punt, as three of the five bores are on the lake or near the lakes edge (see Figure 1.05 below).

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Figure 1.05: Reedy Lake, including surrounding roads and bores (marked as orange stars). Source: MapInfo Data; Dahlhaus, 2006.

2.2.1 Bore Sampling Overview

Groundwater sampling was conducted on the 29th and 30th of August (2006) at Reedy Lake, for major ion and stable isotope analysis (to be conducted by the CSIRO)I. The fieldwork also worked on developing the piezometers, as to build upon current understanding of the physical parameters of the aquifers. The bore sampling also aimed at gathering further data on the major chemistry and isotopes of the groundwater, using the appropriate CSIRO method. An initial sampling programme took place in May (2006), shortly after the bores were installed. It similarly involved developing the bores (for the first time) and sampling the bores, for major ion and stable isotope analysis.

I CSIRO: Land & Water Division.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

2.2.2 Bore Sampling Procedures

There were five bores in total that were developed and then sampled for major ion and stable isotope analysis, at Reedy Lake (see Figure 1.05 above).As to ensure consistency in field work, the same method of sampling was used for each bore. At each bore the SWLII was first recorded (to top of PVC & Collar), the bore was then purged until the water being pumped was reasonably clear. This took some time with several of the bores and approximates were taken, as to the amount of water purged before the water came clear (known as developing the bore).

Purging was completed by using a twelve-volt, battery operated pump, placed at varying depths (see results) within the piezometers (See Figure 1.06 below). The depth to which the pump was lowered was dependent on the length of the screen, the length of the PVC riser and the SWL. The pump was attached to a length of clear hose with 0.25m intervals marked along the hose and the power cable tapped along the outer edge of the hose with two alligator clips attached at the end. These were then connected and removed from the battery as necessary, in order to operate the pump.

Figure 1.06: Bore 4 – Hospital Swamp (SE Corner). Typical pump set up (7meter pump).

II SWL: Standing Water Level.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

The sampling procedure involved calculating the depth of the bore, using an appropriate measuring device (a measuring tape with a weighted end). The depth of the bore was calculated to the top of the PVC pipe and the SWL was subtracted from the total height of the bore. This gave the height of the water within the PVC pipe and the bore volume was then calculatedIII, so that three bore volumes could then be pumped and samples collected.

Samples were collected in three separate bottles marked ‘Anions’, ‘Cations (Acid Added)IV’ and ‘Stable Isotopes,’ respectively. Each bottle was then filled with between 120ml to 130ml of filtered water. Water was collected directly from the pump hose via use of a 60ml syringe and filtered directly into the bottle through a 45µm filter. Bottle lids were only opened when filtering water into bottle, as to reduce the chance of contaminants. It must be noted at this point that while filtering of ‘Stable Isotope’ samples is not necessary, it was conducted in this case.

2.2.3 Single bore recovery tests

Single bore recovery tests were conducted at the five primary bores on the 22nd of November (2006), in order to obtain further information pertaining to aquifer parameters and hydraulic conductivity values. The ability of rocks and sediments to transmit water and hold water, constitute the most significant hydrologic properties (Fetter, 2001). Thus, conductivity values are particularly important in determining the characteristics of the shallow aquifer systems, across Reedy Lake (Hospital Swamp – bore four).

Equipment included the use of a ‘Solinst – Levelogger Gold,’ a laptop for field upload and graphing of data, fox-whistle (for water depth measurement), a 12-volt battery operated pump and a length of stainless-steel cable (used to lower logger into the bore). Field setup and procedure (see Figure 1.07 below, for typical field setup) was

III Bore Volume: V= π r2 h ((Were r = radius of PVC pipe & h = height m) × 1000 (give answer in Liters) × 3 (Three times bore volume)). IV As per the CSIRO sampling method 3 drops (from eye dropper) of HNO3 was added to each Cation sample, immediately after sampling. This prevents adsorption of cations into the walls of the bottle and prevents precipitation of metal hydroxides/ silicates.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION relatively straight forward, first the level-logger had to be setup by connecting it to the computer (via USB port). Then analysing parameters were then uploaded to the logger. For this exercise, it was decided that for the first fifteen minutes the logger would take a reading every second and then every thirty seconds proceeding, for a further fifteen minutes. Once the device was set-up the depth to groundwater in the bore was measured and recorded, then the bore was pumped until sufficient drawdown had been achieved (the bore went dry). After pumping, the pump was then quickly removed and the level logger placed down the bore, to within 15cm of its base. While the pump was being removed from the bore, the level-logger had to be set to recording mode. At this point the logger program will prompt the user that to proceed, all previous data has to be erased (on the logger). Upon selecting to continue the program will further prompt for a data recording start time, this was selected to start immediately. The logger was then removed from its USB dock, attached to the stainless-steel cable and lowerd down into the bore (the varying depths to which the logger was placed can be observed in Appendix W).

Figure 1.07: Typical field setup for bore recovery tests. Author is programming the level-logger, ready to put down bore immediately after pumping (Source: Dahlhaus, 2006).

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Once the level-logger has been placed in the bore the depth to groundwater is measured intermittently, using the fox whistle. This was to monitor when the groundwater had recharged to its original height, in the bore.

Upon the original water height in the bore being achieved, the logger was quickly raised and unattached from the stainless-steel cable. It was then placed on the USB docking station where data was directly downloaded and saved onto the laptop, for initial viewing in the field (as to ensure that the data was what was to be expected and there was no unwanted variables).

2.3 Sampling Analysis

The sampling of groundwater aimed at developing the bores which had not been pumped since May (2006), proceeding installation. Sampling involved collection of groundwater for major ion and stable isotope analysis, with samples taken using the appropriate CSIROV method. The analysis of groundwater aims at developing understanding of the groundwater chemistry and comparisons as to changes in the stable isotope and major ion characteristics of groundwater, since May sampling. The results of the bore water analysis conducted by CSIRO, are discussed latter in this report.

GPS co-ordinates were also logged for each specific bore location, using a Magellan Explorist 100 Series. These were then compared to the GPS readings taken by Miner (2006), upon installation of bores as to ensure correct bore labelling and consistency.

2.4 Computer Modelling

Computer modelling aimed at development of understanding of the lake and its regional setting using a computer modelling program (MapInfoVI), with the aim to produce a number of various models. These models were to be used to depict varying

V CSIRO: LAND & WATER DIVISION VI MapInfo: Version 8.0.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION aspects of the lakes hydrological systems, as well as topographical controls upon it. Modelling also provided a better understanding of regional influences upon the lake, such as the Barwon River, the newer volcanics and possible marine effects.

3. Geology & Geomorphology

The geology of the Lake Connewarre complex according to Coulson (1935), in order of succession includes Lower Miocene to Recent sand, silts and clays with some newer basalt outcrops. The units are evident on the Geological Quarter Sheet 29 N.W., prepared by Daintree in 1861 (see Appendix F) and on the latter 1:250,000 Queenscliff Geology sheet (see Figure 1.08 below).

The presence Lower Miocene fossiliferous yellow clay is believed to form the bed of the lake, although it is not as thick in Reedy Lake as that of other parts of the complex. The depth of the clay in the lake indicates one of two processes that may have helped shape the lake to its present form: Erosion of the tertiary rocks may have taken place or localised subsidence (forming a trough) may have occurred between Reedy Lake and the Salt Works (Stingaree bay: see Appendix F). The trough is bounded to the west by the Newer Basalts and by Lower Pliocene Sands to the East, which are probably the result of faulting. This feature suggests that the post-Miocene bay was more funnel shaped, with the inlet channel connecting to the sea at Stingaree Bay. The Miocene clays and limestone that form the base of the lake system are continuous throughout the area at a slight depth. The clays and limestones are seen in exposures to extend from Belmont and Waurn Ponds to Torquay (Coulson, 1935).

Lower Pliocene sands partially cemented by iron oxides directly overlie Lower Miocene clays/ limestones, in the lake area. Coulson (1935) suggests that the sediments are practically devoid of fossils (with the exception of one locality), which may be owing to the relatively coarse nature of the sediments and their shallow water origin.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

The Newer Basalts are the result of a volcanic eruption from Mt. Duneed, a hill about 100 metres high and situated about eight kilometres west of the lake system. The extrusion of olivine andesine basalt from Mt. Duneed was believed to have occurred approximately during the Upper Pliocene to sub-Recent (Coulson, 1935).

More recent Pleistocene sediments examined at particular localities in the area have a number of shallow marine fossils, identifiable in them (Clark, Cook & Cochrane, 1988). The sediments indicate a period of interglacial sea transgression, which resulted in much of the area being inundated in a shallow marine environment (Clark, Cook & Cochrane, 1988). Pleistocene sediments consist of older bedded dune sandstones, conglomerates consisting of fragments of sandstone of black, grey, brown and cream colours and several feet of travertine (Coulson, 1935).

Recent sedimentary material deposited in the lake system is predominantly composed of silt, sand, sandy clay and shell beds (Coulson, 1935). Sedimentary material in Reedy Lake is probably fluviatile in nature, derived from sediment transported by the Barwon River with some marine influence in recent sedimentation. These form the current bottom of the lake and can be seen in section in the attached Bore Log data (see Appendices, A-E).

Tmn Qra Tpb Qra Kl e Ev Tmn Qpind Qpd Tmn cl Qra Qpd o Tp n Qrd Tmn o Tot Ev QrcFault Qrm M Qrc Tvo Tvo Qvn Tmn Qrd Tmn Qrc Qrd Qrd Tpb Qra Kl Qvn Qrd Tot Qrc t Qrd l line u Qrd Qra noc e a Tot Mo lin F onoc MQra e Qrc Qrd clin t ono l M BoBorrree 222 Qrd u Tpb BoBorrree 666 Tpb a Tot BoBorrree 111 F WATER BoBorrree 333 Qrd Qra Qvn Qrd Tmn Qrd Qrd Qrd Qra Tpb Qrd Qrd BoBorrree 444 Qrd Qrm Qvn Qrd Qrm WATER Qvn Qpd Qrd Qpd Qrd Qpd Qpd Qrm Q Qpd Qrm Qrd Qra Qrd 048 Qpd kilometers Qrd Figure 1.08 Geology of Reedy Lake & Bellarine Peninsula. Source: MapInfo Data; Dahlhaus, 2006.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

3.1 Geomorphology (Landscape Evolution)

Reedy Lake forms part of the Lake Connewarre wetlands system and has formed from a variety of processes, both local and regional in origin. Eustacy, faulting and river migration, have all played a role in shaping the lake to its present form. The complex (Reedy Lake, Salt Swamp, Hospital Swamp & Lake Connewarre) itself forms part of the Moolap sunklands and formed as a result of a series of uplift, transgression and regression events.

At the end of the Lower Pliocene period following the uplift of the Bellarine Horst, the region between Torquay and Ocean Grove was a large funnel-shaped bay. This narrowed to a wide channel at its head, northward towards Corio Bay. The bay forming a shallow marine environment was comprised predominantly of Lower Miocene clay, with areas of Upper Pliocene sediment. The development of barriers as a result of eustatic sea level variations resulted in the formation of the lake system and the deposition of a series of fossiliferous Miocene clay, forming the bed of the lakes (Cecil, Dahlhaus & Neilson, 1988).

The eruption events and formation of Mt. Duneed had a great effect upon the landscape, during the Upper Pliocene (~1Ma; Cecil, Dahlhaus & Neilson, 1988). The extruded lava extended eastward into the bay area, which constitutes the lake complex. It is widely believed that the lava followed depressions in the landscape, such as rivers before spilling out to the surrounds. The lava is seen to divide into three main branches, to the west travelling along the Tait’s Point – Fisherman’s Point ridge, the central branch towards Pelican Rocks in the north east and the southern flow, travelling from the Black Rocks to the Bluff (Cecil, Dahlhaus & Neilson, 1988). The absence of basalt on the uplifted Bellarine Horst is used as evidence to suggest, uplift occurred before the eruption of Mt. Duneed and thus the volcanism provides and excellent time correlation marker.

The basalt flows are believed to have resulted in a damming of the lower Barwon River, resulting in the formation of a series of lagoons. It is believed at this time that

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Reedy Lake was predominantly freshwater and Lake Connewarre and Salt Swamp were predominantly marine, as a result of the basalt flow not reaching the eastern shoreline (Cecil, Dahlhaus & Neilson, 1988). This would mean that Lake Connewarre and Salt Swamp were open to the sea, while Reedy Lake was dammed freshwater from the Barwon River.

The Barwon River eventually broke through the lava flows, between Tait’s Point and Fisherman’s Point, entering Lake Connewarre. The lava barrier at Sheoak Point – Pelican Point was also breached by the river and it continued its course through Salt Swamp to the sea. Periods of great siltation followed this event, resulting in large scale deposition of fine sediments across the lake complex (Cecil, Dahlhaus & Neilson, 1988).

In more Recent times a number of eustatic sea-level variation events have occurred, as a result of glacial activity. During the late Pleistocene (~18,000 years ago) sea-level gradually began to rise (reaching present level by 5000-6000 years ago; (Clark, Cook & Cochrane, 1988). The accumulation of sand dunes along the southern basalt flow on the coast, coupled with the formation of a long sand spit at the mouth of the Barwon River (extending northeast in the direction of the Bellarine Horst) and migration of the river mouth, have resulted from coastal processes. Clark, Cook and Cochrane (1988) suggest that the development of this sandy barrier helped retard drainage from the lower Barwon River and helped shape the current lake system.

3.2 Recent Processes

Reedy Lake is currently a freshwater environment, predominantly feed by diverted water from the Barwon River. It lies behind the basalt barrier separating it from Lake Connewarre with a minor inlet channel which has cut its way through the basalt, connecting the two lakes. Recent development of the lake system has been influenced in large by the Barwon River, with the less turbid waters of Reedy Lake allowing for sediment in suspension to settle. Cecil, Dahlhaus and Neilson (1988) indicate that the basalt barrier separating Reedy Lake from Lake Connewarre, has resulted in the more

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION rapid development of Reedy Lake from an open water system to a swampy environment.

Changes to the lake system as a result of anthropogenic processes, are exemplified by constructions such as the breakwater in the lower Barwon River (Constructed during the mid- 1800’s; Rosengren, 1973). This was designed to stop the migration of brackish water as far as Geelong, which at the time, was dependent on the river as a water supply. A second breakwater was built five miles (approximately 8km) downstream, to prevent further migration of brackish water and allow for a fresh water supply to local farmers/ irrigators. Rosengren (1973) further suggests that the modification of drainage, reclamation and fill, cultivation, quarrying for shell beds, construction of levees and expansion of local tips, have all had influential effects on the evolution of the lake. Concerns are also expressed regarding rates of sedimentation in the lake system, including marked changes in the depth of Lake Connewarre and extension of the deltaic area (Rosengren, 1973).

It is understood that natural infilling of the lake system would have occurred, with a natural build-up of sediment supplied by the Barwon River. Cecil, Dahlhaus and Neilson (1988) suggest that there is little doubt in suggesting that the vast alterations to the catchment since European settlement, has resulted in an acceleration of the process. Vegetation removal and mining influences further upstream along the reaches of the Moorabool River, have contributed to the increased sedimentation rates (Cecil, Dahlhaus and Neilson, 1988). It is best put by Cecil, Dahlhaus and Neilson (1988) that, ‘Clearing of catchments and alteration for agricultural purposes, though in the short-term not as severe as the relatively brief intense impact of mining, have been adding steady sources of sediment above the level which the Greater Barwon catchment would have yielded if it had been left as natural forest and grassland.’ This indicates the strong regional influences in terms of the development and evolution of the lake, with proportion to the impacts of human activities.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION 4. Lake Hydrogeology

4.1 Overview

Reedy Lake forms a freshwater environment, within the Lake Connewarre wetlands complex. Lake Connewarre itself however, is influenced by more saline tidal waters, forming an estuarine lake environment (Stokes, 2002). Understanding of the geomorphology, geology and structural geology, may enable a more accurate interpretation of the development of the lake and what processes may currently be occurring (in terms of surface and ground water systems). It is relevant to suggest that the geology and perhaps the structural geology, play a role in shaping the lakes hydrological system. This may also account for the variability in water chemistry and EC values, obtained in both surface/ groundwater analysis across the lake. However, limiting the breadth of the factors influencing the chemistry/ EC values of groundwater to the geology/ structural geology, would be constraining and a more regional perspective may need to be adopted in terms of influential factors. Elements such as evaporation, runoff, diversion of flows from the Barwon River and saltwater/ freshwater interactions (given close proximity to the sea), may all pay an important role in the lakes hydrological system.

The Barwon River is notably the prominent influencing medium in terms of freshwater supply and sediment supply, to the lake complex. The river has been subject to a number of sampling programs, involving monitoring dissolved salt levels at various points in the river system. This is important in understanding both surficial and groundwater systems and the interactive processes which occur between both. Recent studies (Barton, 2006 et al.) analysed surface water samples taken from the Barwon River system both above and below the Lake Connewarre complex, with particular focus on EC, pH, major ions and stable isotope analysis. It was evident from the results that a large change in the EC values within the system occurs between where the Barwon enters the complex and where it leaves it. The process which drives this change is probably not attributed to one since factor, rather an amalgamation factors may be responsible.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

The regional hydrological setting is also influential in developing understanding the groundwater systems, both in and around the lake. The Werribee Formation which occurs on the downthrown side of the Bellarine Fault and on the Bass Strait side of the Bellarine Horst, has a distinctly saline groundwater quality (2,500 – 4,000mg/L TDS – Total Dissolved Solids). The Newer Volcanics of the Bellarine province receive recharge only directly from rainfall infiltration, however deep weathering and poor drainage result in minimal recharge rates. The salinities within the volcanics are variable and occur within a general range, between 4,000 and 8,000 mg/L TDS. The Torquay Group is also represented in the region by the presence of the Batesford Limestone, which is also host to groundwater. The aquifers within the limestone are highly variable however, they generally only yield limited supplies of saline groundwater. It is understood that salinities within the limestones can vary anywhere between 1,000 – 6,000 mg/L TDS, with that between 4,000 – 6,000 mg/L TDS essentially oceanic in type and may possibly be the result of incompletely flushed connate waters. The Fyansford Formation is also present in the region and generally is host to saline groundwater, ranging between 4,000 – 15,000 mg/L TDS. Recharge is from the overlying strata and from where the formation outcrops, particularly in the Moorabool River Valley (Leonard, 1983).

4.2 Hydrological Observations

The instalment of the six piezometers of which five are used for monitoring, was designed to increase knowledge of any surface/ groundwater interactions and develop understanding of the subsurface environment. The use of bore logs (Appendix A-E) and the development of the piezometers, painted a broad picture into the nature of the subsurface environment and changes in the hydrologic system across the lake. Miner (2006) states in his report that current investigation at the time indicated a consistent base to the lake (Miocene Clays), which acted as a aquitard preventing upward migration of waters (from lower aquifers) into the shallow groundwater systems. The general setting is best described as a large bowl shaped depression, with an undulating base (as a result of palaeochannels) and variable layers of sand, silt and shells (above the clay base; Miner, 2006).

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Preliminary observations of water quality testing of wells as indicated by Miner (2006), point towards possible stratification of the groundwater or the existence of a saltwater/ freshwater wedge within the lake system. Recent monitoring from water result analysis indicates that particular bores such as bore six, appear to indicate strong interactive processes occurring between groundwater/surface water (as indicated by the chemistry and the prevalent EC values). Anomalous values such as that obtained from that of bore three however, paint a different picture and show little relationship between the two mediums. It appears that all the bores show variability in there characteristics, with regard to recharge rates and saline levels. It is clearly discernable that bore three is particularly characteristic given its unusually high salt content, comparative to that of other bores. The relative recovery rates of each bores also gives indications to the permeability of the ground and the nature of the aquifers, giving an overall insight into the greater hydrological setting (see 4.2.1).

It is plausible to suggest that the possibility of a saltwater/ freshwater wedge, as indicated by Miner (2006), may be a major player in the hydrological system of the lake. Higher salinity values in some bores may be attributed to the presence of a saltwater wedge, within the lower reaches of the lake system. Such a wedge would probably be the result of tidal influences, such as that observed in Lake Connewarre. This could be exemplified by poor surface/ groundwater interaction, resulting in minimal dilution and/or long periods of groundwater residence time, in order to accumulate salts and/or the aquifer is hosted by a particularly salt rich source rock.

4.2.1 Single Bore Recovery Tests

Single bore recovery tests were conducted in an attempt to gain a greater understanding of the varying aquifer characteristics, particularly hydraulic conductivity. A description on field procedures concerned, are discussed in section 2.3.3 of this report. The results are tabulated below (Table 1.2) and indicate the varying nature of the aquifer systems, across Reedy Lake and Hospital Swamp. Results were first plotted on log graphs, as per the Hvorslev Slug-Test Method, which

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION is used in cases where piezometers may not fully penetrate an aquifer (Fetter, 2001). It is a useful method by which to determine the hydraulic conductivity of the shallow aquifer systems, which are variable across the lake. The hydraulic conductivity was first obtained by calculating the value of the ratio:

H-h/ H-Ho

Where H was the initial height of water in the bore, h is the water level height below that static water level, after time t and Ho is the height of water in the bore at time zero, immediately after pumping. This value is calculated for each reading and was done via aid of Microsoft Excel Spreadsheet. Once each of these values has been obtained the Hydraulic Conductivity of each of the bores can be obtained from the following equation:

K=r2ln (Le/R) / 2Let37

Where K is the hydraulic conductivity measured in metres/day (m/d); r is the radius of the well casing in metres (m); R is the radius of the well screen (m); Le is the length of the well scree (m) and t37 is the time it takes for the water level to rise or fall 37% of the initial change. The t37 value could be obtained from the spreadsheet data and was confirmed by graphing the data on a log graph (see Appendices Q-T).

The results indicated that shallow aquifer systems across the lake differ greatly and highlight in some cases, the reason for some of the characteristics described in section 4.2.3 of this report. The results indicate that bores one and three have fairly similar hydraulic conductivity values and maybe a function of the sediment types, in which the aquifers exist (silts and silty sands). Bore two is characterised by a very low hydraulic conductivity, which emphasises the slow recharge/ recovery rate of the bore and shows the high variability in aquifer systems across the lake. This is particularly highlighted by the close proximity of bore two, in relation to bore one. Bore four at Hospital Swamp has a particularly high hydraulic conductivity, which is probably a function of the sediment types in which the aquifer exits.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Bore six on the other hand was not able to be assessed using the Hvorslev method, as the rate of recharge was equal to the rate of pumping. In an attempt to measure the hydraulic conductivity the Cooper-Bredehoeft-Papadopulos Methods for a Confined Aquifer, was employed. This involved pouring a known amount of water into the bore, which raises the water to a maximum height Ho above the initial head (Fetter, 2001). The excess head will then decay as the water drains from the well into the formation, as the water level falls the original height (H) and is measured with respect to time (Fetter, 2001). This did not however work as even at a maximum achievable rate of pour, the rate of recharge was too great (see Appendix U). The bore was then pumped and it was found that the rate of recharge was at least equivalent to 10L/85seconds (the pump rate).

Bore ID. Location Hydraulic Conductivity (m/d) Bore 1 Reedy Lake 0.636239 Bore 2 Reedy Lake 0.086948 Bore 3 Reedy Lake 0.482929 Bore 4 Hospital Swamp 1.211918 Bore 6 Reedy Lake N/A Table 1.2: Hydraulic Conductivity, as obtained from single bore recovery test analysis (*Rate of recovery measured pump rate and could not get any drawdown effect).

4.2.2 Bore Log Analysis

The attached bore logs (Appendix A-E) appear to indicate a variety of changes in the aquifer characteristics across the lake, as determined from the logs and comments. Bore one seems to indicate the aquifer is located within fine silts, containing fossil matter and are highly saturated. The above units are however characterised by more clayey silt and silty sand compositions however, they still maintain a very moist structure. This may suggest interaction between the surface and shallow groundwater

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION zones, which is exemplified by the bore characteristics (4.2.3 below). The below strata on the other hand are more clayey impermeable units and seem to indicate a moist but less saturated zone, within the lake sediments.

Bore two displays similar aquifer characteristics to that of bore one, with the aquifer present within the silts and sandy silts, which is indicated by there high degree of saturation. Unlike bore one however the below strata seem to indicate the presence of lower saturated units (possibly indicating deeper aquifer systems) and less moist to slightly moist, units above the saturated unit. This may indicate a relationship between groundwater systems at depth but little interaction, between surface/ groundwater may exist.

Bore three appears to be analogous with that of bores one and two, appears to place the aquifer within silty units (as indicated by there high degree of saturation, from the bore log). The above units seem to indicate relatively little water content, with the upper units of silts and clay slightly moist to dry. Units below the saturated silts appear to grade from very moist to moist, as moving deeper into more clay rich sediments.

Furthermore, bore four located at Hospital Swamp, seems to indicate a shallow groundwater aquifer and is likewise within a silty sand/clay unit (as indicated by moisture content). Underlying this unit is a traces of weathered basalt and overlying is silty sand and clayey silt units. The presence of the weathered basalt at the base of this bore, may account for elevated saline levels (See Appendix D). Bore six in a similar manner to that of previous bores, appears to indicate (from the zone of high moisture content) the aquifer is within silty sand and sandy silt units. The above and below units appear to indicate a more rapid lessening in moisture content towards the surface and a gradual lessening of moisture content, with depth.

It is then discernable from the bore logs that Reedy Lake appears to have a shallow aquifer system, predominantly confined to clay-silts, sandy-silts and silts. Variation in the above and below units (i.e. less/ more permeable layers), gives indications as to

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION the nature of the aquifer and any surface/ groundwater processes that may be at work. The characteristics of the bores is further exemplified by field observations, in development of the five piezometers and is outlined in the section following.

4.2.3 Bore Characteristics

Bore 1:

The SWL in this bore was measured to be at the same level of the lake, within the PVC riser. The bore was discovered to have a reasonably fast rate of recharge, with approximately four litres of water being pumped from the bore every 2-3 minutes (pump depth approx. four metres). Developing the bore however was a laborious process, with the bore water very slowly coming clear and approximately 70 – 75 litres of water was purged (before clear water could be obtained). It was then considered that water was clear enough to be sampled and three bore volumes were then extracted, with samples subsequently taken. The sampling process was time consuming, with approximately 2 – 3 filters required to take the samples for a single bottle (120-130ml). EC & pH readings were also taken of the initial water purged and that after pumping and sampling had been completed, with the water quite brackish.

Bore 2:

This bore is located on the lake area and also required a punt, in order to access the bore. The SWL in this bore also measured that of the lake level and was pumped dry, with approximately four litres of water extracted. This bore was however very slow to recharge, often taking 10-15 minutes between pumps and each time running the bore dry (pump to a depth of 3.75m). The purging of the bore took some time (~2hrs) before the water came clear, however some particulates were still present. Unlike the previous bore it took 3 – 4 filters in order to obtain 120-130ml of filtered water. The very slow recharge rate does indicate that aquifer is sluggish to recharge however, it was faster to develop (murky water – clear water) than that of bore one.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Bore 3:

This bore is located between the lake and the Barwon River, downstream of the break and can be accessed by punt or by foot. This bore was pumped over the two consecutive days, the first day with the peristaltic pump and the second with the battery operated, twelve-volt pump (as to ensure consistency methods). The pump was lowered to a depth of approximately four meters and was subsequently pumped, yielding 3 – 4 litres until the bore went dry. The rate of recharge was reasonable and the bore could be pumped every 2-3 minutes, with 2 – 3 litres extracted at a time. Due to the recovery rate of the bore, it could be pumped until the extracted water was clear in about 35 minutes (1 hour & 45 minutes with peristaltic pump). Sampling proved to be difficult comparative to that of the other bores sampled, with 5 – 6 filters being used per bottle (even though the water being pumped appeared clear). The water was also extremely salty, which is confirmed by previous bore samples conducted earlier in the year. The exact cause of the salty nature of this particular bore is unknown however, the ground water at this point was close to the surface.

Bore 4:

Located at the south east corner of Hospital Swamp, this bore was similar to bore three due to its high saline nature. The Pump was lowered to a depth of 2 – 2.25 meters and the bore was pumped dry yielding approximately two litres of water. The SWL in the bore was almost at lake level, within 10cm of the surface. The bore was quick to recover, with the bore being pumped every 3 -4 minutes and the bore having to be purged a number of times to come clear (about 12 litres extracted until clear). Samples were then taken with a 120 -130ml sample taking about three filters to obtain, relatively less than those of previous bores.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Bore 6:

Bore six is located at Reedy Lake and is west of the inlet channel and was sampled on the two consecutive days. The pump on this bore was lowered to a depth of 3 metres and pumping produced a constant flow of groundwater, indicating the rate of pumping equalled that of recharge. The bore was much faster to develop than that of the other bores sampled, taking only 10-15 minutes to extract clear water. The water level itself in this bore (SWLVII) was about 30cm below the surface and stayed at approximately this level before and immediately after each time the bore was pumped. The second pumping of the bore produced over eighteen litres of water in approximately two minutes, indicating the quick recharge rate. The water itself was brackish but far less salty than that of bores two or three, which are its closest neighbours. Filtering the water was generally much easier process than that of all the bores, with approximately 1-2 filters being used for each 120-130ml sample.

4.3 Hydrogeochemistry

Analysis of groundwater samples was undertaken by CSIRO Land & Water Division and involved major ion and stable isotope analysis, of groundwater samples. Sampling had previously been completed of the five bores, shortly after installation. The second sampling program aimed at achieving two main goals, firstly a comparison of the results obtained previously with those of the recent sampling analysis and secondly, a comparison of results of groundwater analysis with that of recent surface water studies undertaken by the CSIRO.

4.3.1 Major Ion Chemistry

(For Bore Locations Please Refer to Figure 1.05)

Chemical analysis of water is designed to determine the amount of a specific solute, in a specified amount of water (in this case 120ml aliquots were taken for cations/ anions

VII SWL: Standing Water Level.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION from each bore). The analysis of groundwater chemistry seeks to determine the chemical composition of both the surface and ground waters, across the lake. The diagnostic composition of each of the aquifers is generally characteristic of the lithological framework, the initial composition of the water, the type of mineral matter which the water contacts and the pH and oxidation potential of the water (Fetter, 2001). Chemical analysis of groundwater is a useful tool in determining the salinity (TDI) of the samples. The plotting of data is especially useful in determining the separate hydraulic systems involved, via there chemical differences. Clustering of data would indicate that the samples have a similar source of water and therefore, are most likely interconnected (Mazor, 1997). Several clusters would indicate a number of distinct water types in the area, which are isolated from that of others or represent different aquifer characteristics (Mazor, 1997). Similarly, the plotting of both surface and groundwater data on a single graph, could be interpreted in the same way and give insight into and surface/ ground water interactive processes.

+ + 2+ 2+ - 2- Major ionic species of most groundwater’s are Na , K , Ca , Mg , Cl , CO3 , - 2- HCO3 and SO4 (Fetter, 2001). The most common of the positively charged ions (Cations) include sodium (Na+), calcium (Ca2+), potassium (K+) and magnesium (Mg2+; Mazor, 1997). The most common negatively charged ions (Anions) include - - 2- chloride (Cl ), bicarbonate (HCO3 ) and sulphate (SO4 ; Mazor, 1997).

Analysis of groundwater and surface water from Reedy Lake provided invaluable information, into understanding the varying chemistries of water samples. It is evident from the data (Table 1.3 below) that both ground and surface waters are dominated by Na+ and Cl- ions however, less so surface water samples. Bore six does indicate a lower concentration of Na+ and Cl- ions, which may indicate dilution by the nearby Barwon River. This may suggest strong interaction between surface and groundwater particularly at this bore however, the pattern is not reflected across the lake. Bores one and two (on the lake) still have a lower Na+ and Cl- concentrations than bores three and four (perhaps some interaction may be occurring, resulting in slight dilution). Bore three is characterised by particularly high sodium chloride contents, which may indicate the possible presence of a saltwater wedge and perhaps so lithological

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION influence (due to high degree of salt content). The same is reflected in bore four which also has a high sodium chloride content and similarly, may be attributed to the presence of a saltwater wedge and lithological aspects (the bottom of the bore reached basalt and local basalts are known for highly saline aquifer systems).

It can also be noted that iron (Fe) levels in the lake also show a marked change between the initial sampling program and the recent sampling, with strong variation in results. Iron levels in the initial sampling appear to be markedly higher in all bores. This may be accountable due to atmospheric exposure (lake was dry) and the recent bore installation, resulting in oxidation of iron particulates. Since the lake has been filled there has been less ready oxygen available and iron particles have not oxidised as readily, accounting for a drop in Fe levels across the lake.

The piper diagrams (Appendices N - P) show variations in water chemistry, from the initial sampling program and recent sampling programs. They also indicate surface water chemistry and its variability from groundwater. Initial and recent bore sampling results show similar chemistry in each of the bores, with clustering of much of the results (see Figure 1.09). Bore six does stand out on both piper plots as having a varying chemistry, as compared to that of the other bores analysed across the lake. This helps support the hypothesis that a strong interaction between surface water (Barwon River) and groundwater aquifers, may exist at this particular locality. Surface water was also plotted against the initial/ recent groundwater sampling and surface water results (see Figure 1.10) clustered within similar values, to a certain extent. This may indicate that surface and groundwater interaction may be occurring to a certain extent, across much of the lake system.

The combination of both surface water analysis of Reedy and the Barwon River, coupled with the groundwater sampling data (Figure 1.11), provide a means which to correlate all the water chemistry. It appears while the Barwon River has chemistry similar to that of most of the bores and the lakes surface water (as it should, since water is diverted from the Barwon to maintain the lake water level). However it is pertinent to suggest that its (Barwon River) chemistry is leaning towards that

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

expressed by bore six, further strengthening the possibility of interactive surface/ groundwater processes.

Analysis of the various cation/ anions present in the waters and there specific concentrations within the groundwater, surface water and river water, can help identify the hydrochemical nature of the waters. Surface water analysis (conducted by Barton, 2006) from the piper plot appears to indicate from the cations water is of the sodium/ potassium type, with anions indicating it being of the chloride type. This is reflected across all the data, from both the initial/ recent groundwater sampling programmes and the sample taken from the Barwon river by Barton (CSIRO; 2006). The predominance of Na+ (Sodium) and Cl- (Chloride) across much of the waters in the system is further exemplified by the Stiff plots (Figure 1.12 – 1.23) and the Schoeller diagram (Figure 1.24), which show variation in anions/ cations across the initial/ recent groundwater and surface water sampling programs.

- - - Site pH Field Tot Cl Br SO4 Ca K Mg Na S Σc Σa Dif Si Sr Fe EC Alk at n f

dS/m meq/l mg/l mg mg/l mg/ mg/ mg/ mg/l mg mmol(+/-)/l mg/l mg/l mg/l /l l l l /l Reedy Lake Surface Water (July) SW* 7.4 4840 2.4 1102 59 598 152 30 129 642 220 47 47 -0.4 <2.0 1.4 N/A (µS/cm) 8 Reedy Lake Groundwater (August) Bore 7.2 17 14 4720 14 177 479 93 460 2660 620 180 186 -1.6 19 5.6 0.8 1 5 Bore 7.5 19 17 5850 18 157 390 101 517 3230 550 205 216 -2.7 23 5.0 <0.5 2 6 Bore 7.1 60 8.1 2470 75 433 116 337 179 12600 147 762 796 -2.2 10 15.3 <1 3 0 6 6 0 0 Bore 7.1 29 8.1 9540 26 350 101 216 689 5000 114 330 348 -2.7 7 9.2 0.2 4 0 1 0 Bore 7.4 2.9 5.9 742 2 34 84 18 58 413 12 27 28 -0.5 14.2 0.9 0.6 6 Reedy Lake Groundwater (May) Bore 7.3 18 13.9 4980 13 180 541 130 522 3000 673 204 196 1.9 23 6.2 2.2 1 0 Bore 7.9 25 20.1 8330 21 148 377 191 686 4830 575 290 291 -0.1 25 5.0 <1 2 0 Bore 7.5 77 8.4 2862 68 642 123 536 248 15450 215 950 949 0.0 9.6 18 <1 3 0 0 1 0 7 Bore 7.5 25 8.8 1068 26 434 980 375 876 6480 143 412 399 1.6 5.5 11 <1 4 0 0 0 Bore 7.5 3.7 8.2 871 1.7 72 115 28 76 555 27 37 34 3.3 18 1.2 8.6 6 * SW: Surface Water Table 1.3: Table of major ion chemistry analysis of Reedy Lake, including both groundwater sampling data (May, August; 2006) and surface water chemistry (July, 2006).

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Figure 1.09: Piper of combined initial/ recent sampling chemistry (May/ August, 2006).

Figure 1.10: Piper diagram of combined surface and groundwater (initial and recent sampling results).

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Figure 1.11: Combined surface (Barwon River & Reedy Lake) and groundwater (initial/ recent).

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Figures 1.12 – 1.23: Stiff Plots of major ion chemistry of bore water samples (initial/ recent – recent samples denoted by ‘R’) and a stiff plot of the lakes surface water and the Barwon River (Sampled by Annette Barton, CSIRO Land & Water, 2006).

Figure 1.12 Figure 1.13

Figure 1.14 Figure 1.15

Figure 1.16 Figure 1.17

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Figure 1.18 Figure 1.19

Figure 1.20 Figure 1.21

Figure 1.22 Figure 1.23

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Figure 1.24: A Schoeller diagram with the data for both the initial and recent bore sampling chemistry (Recent sampling denoted by letter ‘R’), coupled with Surface Water and Barwon River samples. Source: AquaChem v.3.7.

4.3.2 Stable Isotope Analysis

Stable isotope analysis of water (2H/ 1H and 18O/ 16O) is usually measured with respect to VSMOW (Vienna Standard Mean Ocean Water) and is plotted with respect to the meteoric water line, of the study region. The meteoric water line provides an important key to the interpretation of deuterium and oxygen-18 data (the two isotopes investigated in this study), as it signifies the isotopic processes and origins of the particular water samples (Domenico & Schwartz, 1990).

Analytical results for stable isotopes of deuterium (ơ2H) and oxygen-18 (ơ18O) from both the initial (May) and recent (August) sampling programs, is given in Table 1.4.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Data plotted in Figures 1.25 and 1.26 was plotted against the monthly isotopic data for Melbourne rain:

y = 7.9x + 11.5

The plotted data in Figure 1.25 illustrates the ‘heavy’ isotopic nature of the groundwater, within Reedy Lake from both the May/ August sampling. All the sampled data, including the surface waters, appears to be isotopically enriched. Data from both sampling results appear to indicate, relative differences in the oxygen-18 and deuterium ratios of the groundwater. In the initial sampling results (May) the groundwater appears to be isotopically heavier, than that of the recent sampling (August). This is reflected particularly in the oxygen-18 isotopes, with only bore two and hospital swamp undergoing isotopic enrichment, up to the more recent sampling (comparative to that of the initial). Conversely, deuterium values appear to indicate isotopic enrichment of 2H isotopes between the initial/ recent sampling programmes. According to Domenico and Schwartz (1990) the values that have been plotted on the figures below (Figures 1.25 – 1.26), indicate that enrichment has occurred due to evaporative processes. This may indicate that evaporative processes of surface water across the lake lead to isotopic enrichment, from which the heavier isotopes are then recharged into the shallow aquifer systems.

The variability of groundwater isotopic signatures across the lake however, suggests that this may not be the primary factor for all areas across the lake. To some extent isotopic variability across the lake could be attributed to a variety of pertinent factors, such as lithological influences, fast shallow aquifer recharge rates, salt water wedges (as discussed previous) and differential evaporation rates across the lake system. The inconsistent nature between the initial/ recent sampling programs and whether bores are isotopically ‘enriched’ or are isotopically ‘light,’ can particularly is seen at bores two, three and four.

These bores show marked difference between the initial and recent sampling programs, which could be the result of a number of influencing factors. Bore two is on

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION the margins of the deepest part of the lake and shows a marked increase in ‘heavy’ isotopes, from May to August. Bore three is comparatively different to bore two, as it shows a marked decrease in the percentage of deuterium and oxygen-18. Previous suggestions have indicated the possibility of a saltwater wedge, within the lake system. The drop in ‘heavy’ isotopes between sampling programs may be the result of dilution by isotopically ‘light’ water, since the lake was refilled. Bore four at Hospital swamp shows similar characteristics to that of bore two, in that they note an increase in isotopic richness between the initial/recent sampling results. The cause of this increase cannot be attributed to any particular factor however, hypothetically it is pertinent to suggest plausible reasons for the increase. It may be the case that evaporative processes resulted in an enrichment surface waters and concentration of ‘heavy’ isotopes (within these areas of the lake system), which have had little inflow of istopically ‘light’ water by means of precipitation (in which to dilute). Thus, since the initial sampling, ‘heavier’ isotope concentrations have subsequently been recharged into the shallow aquifer systems.

In the case of isotopic comparisons between the ratios of deuterium and oxygen-18 of the Barwon River and bore six, further links can be drawn between the two systems. The ratios of oxygen-18 and deuterium as listed in the table below, suggest common isotopic composition between the two. This coupled with the chemistry data indicates that strong interaction is occurring between the Barwon River and shallow aquifer systems, particularly within that region of the lake.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

δ Ο18 δD Sample ID ‰ rel V-SMOW ‰ rel V-SMOW Surface Water Analysis (July) Reedy Lake (Sample No. 23) -0.10 -0.8 Barwon River (Sample No. 24) -2.83 -16.2 Initial Groundwater Analysis (May) Site 1 0.36 2.5 2.7 Site 2 0.24 1.7 Site 3 -1.05 -8.4 Site 4 Hospital Swamp 1.85 9.3 9.2 Site 6 -1.81 -12.6 Recent Groundwater Analysis (August) Site 1 0.09 0.18 3.2 Site 2 0.34 4.5 Site 3 -0.76 -2.3 Site 4 Hospital Swamp 2.41 2.30 15.0 14.3 Site 6 -1.62 -9.3 Table 1.4: Stable Isotope Analysis data of initial (May) and recent (August) sampling of groundwater, coupled with surface water stable isotope analysis (conducted by Annette Barton, July 2006).

Corangamite Regional water isotope data

0 w o v-sm

H -10 2

δ Meteoric water line

-20 Reedy Lake (May)

-30 VSMOW

Reedy Lake (August) -40 -6 -4 -2 0 2 4 18 δ Ov-smow

Figure 1.25: Stable isotope data from May/ August sampling, plotted against meteoric water line for Melbourne (adapted from Dahlhaus, 2006).

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Corangamite Regional water isotope data

0 w smo v-

H -10 2 Meteoric water line δ Reedy Lake (May) -20 VSMOW

Reedy Lake (August) -30 Reedy Lake Surface Water

Barwon River -40 -6 -4 -2 0 2 4 18 δ Ov-smow

Figure 1.26: Stable isotope data for both initial/ recent groundwater analysis, coupled with surface water analysis obtained for Reedy Lake and the Barwon River by Annette Barton (CSIRO, 2006; adapted from Dahlhaus, 2006).

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

4.4 Conceptual hydrological model

Figure 1.27: 3D-conceputal model of Reedy Lake, vertically exaggerated and overlain by Queenscliff 1:250 000 Geological Map.

The hydrological setting of Reedy Lake can best be described as a complexity of aquifer systems, which have variable relationships with the lakes surface water and may be subject to other influencing factors. To aid in understanding of the aquifer characteristics and possible influential factors, including surface water processes and topographical influences, computer modelling techniques where employed. Using MapInfo v8.0 to develop three dimensional models (Figure 1.27) as well as cross- sections (Figure 1.28), the general setting of the lake could be explored to better understand the lakes hydrological setting and influences upon it.

As discussed previously in 4.2.2 bore log analysis it appears that shallow aquifer systems within the lake, are predominantly confined to silts and silty sands. Miner (2006) suggests that the silty clays are of the Fyansford formation and are probably

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Miocene in age. These form the base of the lake and are best described as a ‘bowl like’ layer, at the foundation of Reedy Lake (Coulson, 1935). The overlying sands and silty sands which are fossiliferous in nature, show variations in depth and are probably associated with the former alignment of the Barwon River (Miner, 2006). Modelling of radiometric data as well as cross-sections, obtained from topographic data, helped identify topographic low points within the lake system. The data provided information as to low points of the lake but is not detailed enough, to be able recognise specific palaeochannels of the Barwon River. It could be assumed that variability in the sediments across the lake is most probably a function of the palaeochannel directions, in which aquifers may occur as lenses. Inconsistency of sedimentary strata probably means that the aquifer systems are confined to certain stratal zones, by means of stratigraphic aquitards.

Bore four at Hospital Swamp is probably influenced by the underlying basalts, which are overlain by clays and silts (Miner, 2006). The exact effect the basalts of the Newer Volcanics have on the groundwater is unknown and suggested influences are purely based on assumptions. It is evident from the potassium radiometric response (Figure 1.29) that sediments form the base of the lake system (Reedy Lake and Hospital Swamp). These sediments are underlain by the ‘bowl like’ clays seen at Reedy Lake and the Newer Basalts, seen at Hospital Swamp. At bore four it is possible that the underlying basalt may be interacting with the shallow aquifer systems, forming the base of the swamp. As discussed previous the New Basalts are known to host highly saline aquifer systems, which may account for the abnormally high saline values at bore four. This assumes that there is a direct relationship between the shallow aquifer systems that exist at hospital swamp and the underlying basalts. The possibility of a saltwater wedge within the system would however discount this hypothesis and may account for the high salt levels.

It is thus necessary to suggest that the aquifer systems at Reedy Lake/ Hospital Swamps, are not defined by any one influential process and should be treated accordingly. The main assumption is that the aquifer systems are primarily controlled by their varying strata, with the possibility of external influences such as the presence

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION of a saltwater wedge. Sedimentary strata appear to be the controlling variables in the ability for water to interact with the surrounding water systems, above and below aquifer systems.

Figure 1.28: Cross-sectional diagram of Reedy Lake, taken from above 3D- conceptual model. Green line represents the normal topographic height across the lake, where the red line illustrates vertically exaggerated section across the lake.

Figure 1.29: Airborne Radiometric data. Potassium response (purple) is restricted to regions of topographic lows (Source: Dahlhaus, 2006).

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION 5. Discussion

Reedy Lake appears to have a dynamic hydrological setting, which is characterised by a diverse number of influential factors. Differing aquifer systems within the lake are primarily concerned with variations in sedimentary layers, that form the lake base. The chemical and isotopic data obtained indicates that some degree of interaction is occurring between the surface and groundwater, across the lake. This degree of interaction appears to be proportionate to the controls of the sedimentary strata, which define the lake base. Henceforth, there are a number differing isotopic and chemical signatures of the ground/ surface waters across the lake system.

External controls upon the lake and its aquifer systems appear to be both from surface water, such as the Barwon River and the geological controls of the surrounding area. The surrounds and the lake itself form part of a coastal estuarine complex, which in its lower reaches, is still affected by marine tidal activity. Investigation of the bore water chemistry and stable isotope data indicates the possibility for marine processes extending into Reedy Lake, in the form of a saltwater wedge. The exact temperament of marine influences upon the lake are not known and require further investigation, as to determine there exact nature.

The Barwon River itself is also a major contributor to surface water within the lake system, with water diverted from the river to maintain lake level. The extent of the Barwon’s influence on the lake system is unsure but evidence from ground/surface water chemistry, suggests that strong interaction is occurring between the two mediums (particularly bore six). Its influence throughout time may also be of concern, as the migration of the river may have had profound influence on lake sediment build- up/ supply and the development of lake aquifer systems.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION 6. Conclusion Reedy Lake is a diverse and complex hydrological environment, which has been shaped by both regional and local geological processes. It can be concluded from the various aspects investigated at the lake that: 1. Reedy Lake which forms part of the Lake Connewarre wetlands complex, is a predominantly a freshwater environment; 2. The lakes base has been forming since the Miocene, with a series of transgressive/ regressive events shaping the base of the lake; 3. The Barwon River has also been a major contributor to sediment to the lake, with the migrating river channel resulting in variable sediment accumulation across the lake; 4. The lakes aquifer systems are characterised by varying sediment types, with aquifers restricted by stratal variations above and below; 5. Single bore recovery tests indicate that aquifer characteristics are variable across the lake and are most probably a function of there host sediment type; 6. Interaction between surface and groundwater is probably attributed to the sediment type variations, which constitute the base of the lake; 7. Major ion and stable isotope data appears to indicate that interaction between surface water and groundwater is occurring but is variable; 8. Some aquifers have inherently high salinity levels, which may be the result of regional geological influences (i.e. Hospital Swamp and Newer Basalts) or possibly coastal processes, such as a saltwater wedge; 9. The lakes vegetation provides a good indication as to the nature of the surface/ shallow groundwater hydrologic systems;

The complex variability of the lakes hydrology and its dynamic surface/ groundwater systems, are a function of both constraining lake characteristics and more regional geomorphic processes. The diverse nature of the lakes aquifer systems and groundwater characteristics cannot be simply attuned to one single process, rather a multitude to factors play a vital role in shaping the differing aquifer systems. It is also pertinent to acknowledge that surface water systems play a diverse and vital role, in shaping the lakes hydrological system.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION 7. Recommendations for further research

It can be discerned from this study that a number of aspects require further consideration and research, in order to fully understand the diversity of the lakes hydrological setting:

1. The establishment of further groundwater monitoring bores, perhaps another 6 -8 bores, in order to further understanding of the subsurface aquifer systems towards the coast; 2. Geophysical surveys, in particular the use of electromagnetics. This technique could be used to determine saline aquifers and to determine the nature of the saltwater/ freshwater interface; 3. Continued monitoring of the established bores including EC and water level measurements, which will help establish seasonal variations and further understanding of the aquifer system dynamics; 4. Further sampling of groundwater for major ions and stable isotopes, will also show variations in water chemistry over time and may allow greater understanding of the differing aquifer chemistry and there variability over time;

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION 8. References

REFERENCES

Stokes, D., (2002). Tidal Dynamics and Geomorphology of the Lower Barwon Tidal Inlet. A thesis submitted in partial fulfilment of requirements for the Honours Degree of Bachelor of Ars. School of Arts & Education. La Trobe University, Bendigo, Victoria. Australia.

Clark, I., Cook, B. & Cochrane, G.C., (1988). Victorian Geology Excursion Guide. Australian Academy of Science, Canberra. Australia. 489p.

Cecil, M.K., Dahlhaus, P.G. & Neilson, J.L., (1988). Lower Barwon – Lake Connewarre Study. Geological Survey Division. Department of Industry, Technology and Resources, Victoria. Australia. 47p.

Ecological Associates, (2006). Reedy Lake Groundwater and Ecology Investigation. Report BX003-A prepared for Corangamite Catchment Management Authority, Colac, and Parks Victoria, Melbourne.

Leonard, J.G., (1983). Preliminary Assessment of the Groundwater Resources in the Port Phillip Region. Geological Survey Report No.66. Publication No. 219, Ministry For Conservation Environment Study Series. Geological Survey, Victoria. Australia.

Fetter, C.W., (2001). Applied Hydrogeology. Fourth Edition. Prentice-Hall, Inc. Upper Saddle River, New Jersey. United States of America. 598p.

Domenico, P.A & Schwartz, F.W., (1990). Physical and Chemical Hydrogeology. John Wiley & Sons, Inc. United States of America. 824p.

Mazor, E., (1997). Chemical and Isotopic Groundwater Hydrology – The Applied Approach. Second Edition, Revised and Expanded. Marcel Dekker Inc., New York. United States of America. 413p.

Barton, A., Herczeg, A, Cox, J. & Dahlhaus, P., (2006). Sampling and analysis of lakes in the Corangamite CMA region. Report to the Corangamite Catchment Management Authority CCMA. Project WLE/42-009: Client Report 3. CSIRO Land and Water Science Report 34/06, September 2006.

Miner, A.S., (2006). Installation Report for Groundwater Wells at Reedy Lake and Hospital Swamps, Parks Victoria. Report No: 337/01/06. A.S. Miner Geotechnical, Consulting Engineers. Manifold Heights, Victoria. Australia

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION 9. Appendices

Appendix A: Bore 1 log, Reedy Lake. Source: Miner, 2006.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Appendix B: Bore 2 log, Reedy Lake. Source: Miner, 2006.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Appendix C: Bore 3 log, Reedy Lake. Source: Miner, 2006.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Appendix D: Bore 4 log, Reedy Lake. Source: Miner, 2006.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Appendix E: Bore 6 log, Reedy Lake. Source: Miner, 2006.

Appendix F: Map of Lake Connewarre Complex. Source: Coulson, 1935.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Appendix G: Major Ion Analysis – May 2006 (Source: J. Dighton (CSIRO), 2006).

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Appendix H: Major Ion Analysis – August 2006 (Source: J. Dighton (CSIRO), 2006).

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

JOB # 06135 δ Ο18 δD

Sample ID ‰ rel V-SMOW ‰ rel V-SMOW

Site 1 0.09 0.18 3.2 Site 2 0.34 4.5 Site 3 -0.76 -2.3 Site 4 Hospital Swamp 2.41 2.30 15.0 14.3 Site 6 -1.62 -9.3

Appendix I: Stable Isotope Analysis – September 2006 (Source: CSIRO - Land & Water; Adelaide; 2006).

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

JOB # 0678 δ Ο18 δD

Sample ID LAB ID ‰ rel SMOW ‰ rel SMOW

BORE 1 49986 0.36 2.5 2.7

BORE 2 49987 0.24 1.7

BORE 3 49988 -1.05 -8.4

BORE 4 49989 1.85 9.3 9.2

BORE 6 49990 -1.81 -12.6

5290 49991 -5.69 -32.8

Appendix J: Stable Isotope Analysis – June 2006 (Source: CSIRO - Land & Water; Adelaide; 2006).

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Appendix K: Field Sampling Spreadsheet – 29th to 30th August 2006.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

APPENDIX L: Surface Water Major Ion Analysis (Barton, Herczeg, Cox and Dahlhaus, 2006):

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Appendix M: Surface Water – Stable Isotope Analysis (Barton, Herczeg, Cox and Dahlhaus, 2006):

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Appendix N: Piper diagram of surface water chemistry of Reedy Lake – Sampled by Annette Barton (July, 2006) – CSIRO Land & Water Division.

Appendix O: Piper of initial sampling program chemistry – Sampled by Joanne Mannis & Marcus Horgan (May, 2006) – University of Ballarat.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Appendix P: Piper diagram of recent sampling chemistry (August, 2006).

Log Graph 1 0 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 7 25 50 75 10 12 15 17 20 22 25 27 30 32 35 37 40 42 45 47 50 52 55 57 60 62 65 67 70 72 75 77 80 82 96 1 . 0

(H-Ho) Log Graph )/ (H-h 1 0 . 0 1 00 0. Elapsed time (seconds) Appendix Q: Bore 1. Plot of head ratio vs. time used for Hvorslev method in single bore recovery tests (Dahlhaus, 2006).

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Log Graph - Bore 2 1 0 500 1000 1500 2000 2500 0.1 ) o -H /H -h H ( 0.01 0.001 Time (Seconds) Appendix R: Bore 2. Plot of head ratio vs. time used for Hvorslev method in single bore recovery tests.

Log Graph - Bore 3

Elapsed Time (Seconds) 0 200 400 600 800 1000 1200 1400 1 .1 0 o)

Log Graph -h/H-H (H 1 .0 0 1

0.00 Appendix S: Bore3. Plot of head ratio vs. time used for Hvorslev method in single bore recovery tests.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Log Graph - Bore 4 1 0 200 400 600 800 1000 1200 1400 1600 1800 0.1 o) -H H

/ Log Graph -h H ( 0.01 0.001 Elapsed Time (Seconds) Appendix T: Bore 4. Plot of head ratio vs. time used for Hvorslev method in single bore recovery tests.

Bore 6

350

300

250

) 200 m c

l ( Bore 6 ve

Le 150

100

0 11:34:05 11:35:31 11:36:58 11:38:24 11:39:50 11:41:17 11:42:43 11:44:10 11:45:36 11:47:02 Time (Seconds) Appendix U: Bore 6. Plot of attempted ‘Cooper-Bredehoeft-Papadopulos Method.’ Only slight rise in head noticed by pouring water in the bore.

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Appendix V: Site Photos.

Bore 1: Developing bore (August). Bore 2: Single Bore Recovery Tests (November).

Bore 3: Single Bore Recovery Tests Bore 4: Ray Agg & Peter Dahlhaus, conducting single bore recovery tests (November). (November).

Bore 6: Single Bore Recovery Tests (November; Above: View Across Lake with Ray & Grant in Source: Dahlhaus, 2006). the punt in the middle distance (Source: Dahlhaus, 2006).

REEDY LAKE – SURFACE/ GROUND WATER INTERACTION

Appendix W: Single Bore Recovery Tests.

Bore Id Location Standing Level logger Level Water Level Depth (m) Logger Start (SWL; metres, Time (24hrs) m) – To top of collar Bore 1 Reedy Lake 1.33m 3-3.5m 1357 Bore 2 Reedy Lake 1.52m 4.5m 1441 Bore 3 Reedy Lake 1.89m 3.5-4m 1227 Bore 4 Hospital 1.78m 2.5-3m 1001 Swamp Bore 6 Reedy Lake 2.23m 4m 1140