Barwon Downs borefield licence renewal

We have expanded our ongoing monitoring of the Barwon Downs borefield ahead of an application to renew our groundwater licence.

Have your say

Learn more, join the conversation and have your say on the Barwon Downs borefield licence renewal process at our dedicated microsite.

  Your Say: Barwon Downs borefield licence renewal

Background

The Barwon Downs borefield is a crucial emergency water source for greater Geelong when surface storages are low.

In 2007, at the height of the worst drought on record, Geelong’s water storages dropped to just 14% and the borefield, at times, provided up to 70% of the city’s daily drinking water.

Barwon Water operates the Barwon Downs borefield under licence from Southern Rural Water, due for renewal in June 2019.

We reviewed the existing monitoring program and decided to expand it to improve the quality and quantity of data collected. The data will be used in an application to renew the licence.

 

About the borefield

The Barwon Downs borefield consists of six bores that pump groundwater from an aquifer 300 to 630 metres below ground.

For the purposes of managing and licensing groundwater use, the borefield is contained within a defined boundary known as the Gerangamete groundwater management unit (GMU), one of 34 defined GMUs in Victoria. The Gerangamete GMU is estimated to contain approximately 14,000 gigalitres of groundwater – approximately half the capacity of Port Phillip Bay!

 

The Barwon Downs borefield consist of six groundwater bores that pump groundwater from an aquifer 300 to 630 metres below ground. The red circle indicates the approximate area from which groundwater is extracted. 

 

Groundwater licence

Southern Rural Water is responsible for licensing groundwater extraction in southern Victoria.

Barwon Water’s licence was granted in 2004 and expires in 2019.

As part of the licence we monitor and report on:

  • groundwater levels and pressures
  • groundwater quality (including salinity)
  • groundwater pumping rates
  • subsidence
  • flows in Boundary Creek and the Barwon River
  • vegetation health.

Our monitoring area covers approximately 500 square kilometres and includes parts of Birregurra, Deans marsh, Gerangamete, Barongarook, Pennyroyal, Yeodene and Murroon.

 


 

Community interest

Although the current monitoring program complies with licence conditions, there has been increasing community interest about potential environmental impacts.

Key areas include:

  • stream flows in boundary creek
  • possible acid-sulfate soils at the Yeodene peat swamp
  • possible increased fire risks at the Yeodene peat swamp
  • whether pumping limits are reasonable under future climate change projections.

 

Community reference group

In October 2013 we established a community reference group in to provide feedback on the monitoring program and our engagement with the local community.

The group contains 8 representatives from a range of community sectors, including business, industry, landowners, environmental groups, farmers and the general community. They meet regularly throughout the year.

  • Jan Greig, Chair and Murroon resident
  • Doug Chant, Deputy chair, farmer and Warrion resident
  • Henry Bongers, Colac customer
  • Robin Povey, Geelong customer
  • Gavin Brien, farmer and Barwon Downs resident
  • Robert Maxwell, farmer and Gellibrand resident
  • Hans Fankhanel, Otway Ranges Environment Network representative and Wyelangta resident
  • Malcolm Gardiner, Land and Water Resources Otway Catchment representative and Kawarren resident.

 


 

Expanded monitoring program

The monitoring program aims to:

  • better understand environmental impacts of groundwater pumping
  • recognise how drought and land use contribute to environmental issues
  • provide additional data to support licence renewal.

 

The expanded monitoring program addressed five main components:

  1. groundwater
  2. terrestrial ecology
  3. acid sulfate soils
  4. aquatic ecology
  5. stream flow.

 

Groundwater monitoring

Groundwater is monitored via dedicated observation bores. Monitoring has continued since the borefield began operating more than 30 years ago.

Groundwater monitoring aims to improve the understanding of groundwater behaviour, the connections with surface water, and any changes to groundwater levels due to pumping or climate.

As part of the upgraded monitoring program, we have installed 37 new monitoring bores, repaired 3 old bores, and increased groundwater quality sampling.

 

Terrestrial ecology

Terrestrial ecology monitoring aims to better understand the relationship between groundwater, groundwater pumping and surface ecosystems.

We undertakes periodic surveys of plant life at sites where vegetation may dependent on groundwater.

The monitoring program has been expanded to 13 sites including 11 new ones incorporating stream banks, wetlands, swampy scrub and woodland.

 

Acid sulfate soils

Acid sulfate soils are those that contain iron sulfide minerals (notably pyrite, or “fool’s gold”) and occur naturally under waterlogged conditions.

Undisturbed and below the water table, acid sulphate soils pose no risk. However if the soils are drained or exposed to air by the lowering of the water table, the sulfides react with oxygen to form sulfuric acid. This can release iron, aluminium and other metals within the soil, and has the potential to adversely affect the local aquatic and terrestrial ecosystems.

Although we are not required to monitor acid sulphate soils as part of our groundwater licence, we are monitoring four sites as part of the upgraded program.

 

Aquatic ecology

We release flows into Boundary Creek to comply with our current licence and maintain healthy habitats for aquatic life.

An aquatic ecology team will identify, examine and monitor the flora and fauna in suitable habitats on Boundary Creek. We will measure and monitor flow levels in the creek.

Data from the upgraded monitoring program will help determine whether the volume and timing of the releases are appropriate, and whether improvements could be made to better maintain healthy aquatic ecosystems.

 

Stream flow

We monitor passing flows in Boundary Creek and the Barwon River as part of our current licence.

Stream flow monitoring aims to better understand the connection between surface water and ground water, including groundwater recharge areas.

The new monitoring program will include upgraded stream gauges and dataloggers at selected sites on Boundary Creek and the Barwon River.

 


 

Progress

Stage 1 Review the monitoring program 2012 (complete)
Stage 2 Finalise scope of the expanded monitoring program 2013 (complete)
Stage 3 Install new monitoring equipment 2014 to 2015 (complete)
Stage 4 Ongoing monitoring 2014 to 2017 (in progress)
Stage 5 Analyse monitoring data 2017 to 2018
Stage 6 Application for licence renewal Licence expires June 2019