A BRIEF AUDIT OF THE CORANGAMITE GROUNDWATER MONITORING PROGRAM November 2001 AGRICULTURE VICTORIA - BENDIGO CENTRE FOR LAND PROTECTION RESEARCH Monitoring Report No. 42 Ó The State of Victoria, Department of Natural Resources & Environment, 2001 Published by the Department of Natural Resources and Environment Agriculture Victoria - Bendigo – Centre for Land Protection Research Cnr Midland Highway and Taylor St Epsom Vic 3551 Australia Ó The State of Victoria, Department of Natural Resources & Environment, 2001 Published by the Department of Natural Resources and Environment Agriculture Victoria - Bendigo – Centre for Land Protection Research Cnr Midland Highway and Taylor St Epsom Vic 3551 Australia Website: http://www.nre.vic.gov.au/clpr The National Library of Australia Cataloguing-in-Publication entry: Pillai, Mayavan A brief audit of the Corangamite groundwater monitoring program ISBN 0 7311 4989 0 1. Groundwater – Victoria – Corangamite, Lake, Region. 2. Hydrogeological surveys – Victoria – Corangamite, Lake, Region. I. Centre for Land Protection Research (Vic.). II. Title. (Series : Monitoring report (Centre for Land Protection Research) ; 42). 551.49099457 ISSN 1324 4388 This publication may be of assistance to you but the State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication. Agriculture Victoria Bendigo - CLPR SUMMARY Across the Corangamite Salinity Region there are in the order of 580 NRE and community groundwater monitoring bores, grouped in 28 distinct monitoring networks that have progressively been established since the late 1980s. These networks contain bores that tend to be concentrated in areas where salinity is a major land degradation issue. The majority of the monitoring (in excess of 55% of bores) is currently undertaken by paid community groundwater monitors. However, numerous management issues have arisen with respect to the community groundwater monitoring program. These issues revolve around the loss of community monitors and a drop in monitoring standards due to a lack of direct support received by the community monitors from government agencies. Management of a community groundwater monitoring program requires a substantial investment of resources. Groundwater monitoring data is the key component to the understanding of groundwater behaviour and water balance. Thus the monitoring program needs to be efficient, representative and appropriately resourced. Agriculture Victoria Bendigo - CLPR i Agriculture Victoria Bendigo - CLPR CONTENTS Summary .................................................................................................................... i 1 Objectives.............................................................................................................1 2 Background...........................................................................................................1 3 Status of NRE and community groundwater monitoring program...........................2 3.1 Inventory and nature of monitoring. ................................................................2 3.2 Current monitoring breakdown .......................................................................2 3.3 Future monitoring requirements .....................................................................2 4 Monitoring program issues....................................................................................3 4.1 Breakdown in roles of responsibility.................................................................3 4.2 The size of the monitoring program..................................................................3 4.3 Lack of effective maintenance capacity ...........................................................3 5 Recommendations ................................................................................................4 6 Acknowledgments.................................................................................................4 7 References ...........................................................................................................4 Appendix 1 Table of the summary of NRE and GDB (Groundwater Data Base) bores. Map 1 Groundwater monitoring bore network and monitors. List of Tables Table 1 List of current key bores ...............................................................................5 Agriculture Victoria Bendigo - CLPR i A BRIEF AUDIT OF THE CORANGAMITE GROUNDWATER MONITORING PROGRAM November 2001 MAYAVAN PILLAI Centre for Land Protection Research, Department of Natural Resources & Environment, Cnr Midland Highway & Taylor St, Epsom. Vic. 3551 1 OBJECTIVES The principle objectives of this monitoring audit are: · To provide an up-to-date inventory of the Department of Natural Resources and Environment (NRE) and community groundwater monitoring program within the Corangamite Catchment Management Authority (CMA) Region. · To briefly identify the issues and deficiencies with respect to the current groundwater monitoring arrangements. · To recommend some general direction for the future of the NRE and community groundwater monitoring program. 2 BACKGROUND This audit is the first since the broadscale adoption of community groundwater monitoring across the Corangamite region in the late 1990s. It is particularly significant because it pulls together the issues surrounding a somewhat more disaggregated program. This audit is part of a process to achieve an efficient and effective groundwater monitoring program. This is crucial for: - understanding the character and state of groundwater systems prone to or contributing to salinisation; and - informing of hydrological trends (especially long-term trends) in the scenarios of no intervention and treatment. This review follows previous detailed documentation of the Corangamite Salinity Region NRE groundwater monitoring program by Heislers (1996a, 1996b). This audit is specific to the NRE salinity groundwater monitoring network, as opposed to the broader statewide groundwater monitoring network and groundwater data base (GDB) that is managed by Sinclair Knight Merz (under contract from NRE). However, information from the latter is significant with regards to assessing salinised aquifers and trends, and as such, numerous piezometers from this statewide network are a part of the updated Corangamite CMA Region bore list provided in this report. Agriculture Victoria Bendigo - CLPR 1 3 STATUS OF NRE AND COMMUNITY GROUNDWATER MONITORING PROGRAM 3.1 Inventory and nature of monitoring The program consists of around 580 bores in 28 different bore monitoring areas distributed within the Corangamite Salinity Region. A current inventory is contained in the form of an attached map, with individual bore details listed in the appendix. The bulk of the bores within the program have been constructed by NRE to a maximum depth of 20 m below ground level using a trailer mounted auger. Due to the limitation of the auger, most of the bores are located in the lower landscape, where the ground is generally softer and comprised of a deeply weathered layer. The bores are often positioned in pairs or triplets (bore nests) so as to determine the nature of the vertical movement of the watertable in the vicinity of the bore. As a rule a paired nest will usually contain 5 m and 20 m bore depths, while a triplet nest contains 5 m, 10 m and 20 m bore depths. These bores are commonly sited in a line or transect along a slope to determine the shape of the watertable which indicates the nature of the groundwater flow system. 3.2 Current monitoring breakdown Monitoring status Of the 580 bores, about 29% (166 bores) of these have had a monitoring lapse or suspension, thus 414 bores are currently monitored. A lapsed bore is where the database has been informed that it is no longer being monitored, despite it being recognised as a proclaimed monitoring point. Few bores have actually been formally suspended from the monitoring program, though this may occur if the bore is deemed not to serve a useful purpose, or to have been damaged beyond repair. Frequency of monitoring The database reveals the following monitoring periodicity: Monthly 75% (310 bores) Two-monthly 19% (79 bores) Quarterly 6% (25 bores) In the past, efforts to constrain the size of the monitoring program has tended to be achieved by reducing monitoring frequencies rather than suspending bores. As such, a ‘mandatory’ groundwater monitoring network does not actually exist. Monitor type Monitors can broadly be categorised be broken down as follows: Agency monitored bores 38% (158 bores) Paid community monitored bores 56% (231 bores) CMA/Landcare monitored bores 6% (25 bores) 2 Agriculture Victoria Bendigo - CLPR 3.3 Future monitoring requirements Whatever groundwater monitoring strategy is embraced in the future, it is clear that the scope of the monitoring program needs refinement to increase its efficiency and effectiveness. The integrity of the data produced from this program is foremost, then the mechanisms affecting the program can be determined. Resource limitations may mean that, out of necessity, the program may have to operate differently in the future. In refining the scope of the program the concept of key bores (see Heislers 1996a) is a useful first step. Future monitoring strategies can be based around this core. The key bore network