Water Storage Manager 2024-25 Water Quality Annual Report

 Figure 1: GMW's area of operation.

GMW’s commitment to drinking water quality management is reflected in the corporate Safe Drinking Water policy, which was last reviewed in August 2024.The objective of this policy is to ensure that GMW meets its obligations as a WSM under the Act and Regulations. It requires GMW to address threats to safe drinking water as a WSM by preparing and implementing a risk management plan in relation to its supply of water to an urban Water Supplier.

GMW is required to apply risk management for all the water supply mechanisms it uses to provide water to urban Water Suppliers. This includes risks associated with:

• the catchment leading to each storage
• each storage itself
• the supply of water downstream of storages using natural carriers such as rivers and creeks
• the supply of water via channel and pipeline systems.

A Risk Management Plan (RMP) has been prepared and implemented in accordance with the Act and Regulations. It is regularly reviewed by GMW. The plan outlines GMW activities to manage the risks to water quality and includes a section that focuses on risks in and around GMW’s storages and within GMW’s irrigation districts.

GMW communicates regularly with urban Water Suppliers to share information and discuss any issues arising from the RMP and operations, including incident response, blue-green algae risk and water resource management. Engagement with each urban Water Supplier includes two scheduled meetings per year and additional communication when required.

Urban Water Suppliers are also invited to participate in GMW’s risk identification and review process for the storages and irrigation systems relevant to their town offtakes. This involves participation in a workshop to ensure that all hazards to water quality are identified and appropriately rated, which helps to ensure a consistent understanding of hazards amongst the organisations. The risk assessment reviews are scheduled for every three to five years, with the frequency dependent on a calculated overall risk rating for each location. During 2024/25, risk assessments were reviewed for nine systems (see Section 3.1).

GMW has a Memorandum of Understanding with each of the six regional urban Water Suppliers, Melbourne Water and Melbourne’s three metropolitan water corporations that documents commitment by the parties to work together and share information relevant to the implementation of their respective RMPs.

GMW also engages with representatives of the North East, Goulburn Broken and North Central Catchment Management Authorities (CMAs) and other organisations with a role in land and/or water management to enable strategic and operational planning, knowledge exchange and a coordinated approach to issues affecting water quality.

Regular water quality monitoring is undertaken at GMW storages for blue-green algae (BGA) and basic water quality parameters including nutrients, pH, turbidity and electrical conductivity. The frequency of monitoring at each location is based on BGA risk, which is determined from the frequency of historical blooms and the consequence of high BGA levels. The consequence takes into consideration the presence of town offtakes, size of population supplied, the type of recreation permitted and popularity. All storages are monitored at least monthly. Additional monitoring is usually undertaken during the warmer months at storages with a history of water quality issues. Water quality is generally better in the east of GMW’s area of operation, so those storages are sampled monthly. In the western area, sampling is generally undertaken 18 times a year and biased toward the warmer months due to elevated BGA risk. As GMW uses a risk‑based approach to monitoring, extra sampling is often initiated through the year in response to laboratory results and field observations. Regular testing for BGA is undertaken in other parts of GMW's system where it has been determined, based on historical records, that there is a likelihood of high algae counts.

All water quality results are reviewed when received. Anomalous results are investigated, documented and reported to relevant stakeholders, including urban Water Suppliers.

GMW provides advice to urban Water Suppliers on BGA levels at locations with direct town water supply offtakes within 48 hours of receiving the results. Section 2.1 provides an overview of BGA management and warnings during 2024/25 related to water provided to urban Water Suppliers.

Data is summarised annually into a Water Quality Index, based on comparison with state and national guidelines. Relevant raw water quality data and Water Quality Index scores for GMW storages are shared with urban Water Suppliers that have indicated that they would like to receive this information.

Regulation 17 – Additional details to be included in annual reports of water storage managers:

1. information about actions taken by the water storage manager in respect of each emergency, incident or event that has arisen that has affected
   1. the quality of the water supplied for drinking purposes generally; and
   2. the quality of the water supplied where that supply posed a risk to human health;
2. any issues that may have arisen out of the taking of the actions referred to in paragraph (a).

Section 22 Notifications

There were no incidents that required GMW to report to DH under section 22 of the Act during 2024/25.

Other emergencies, issues or events

The catchments in northern Victoria where water is harvested are open to a wide variety of land- and water-based activities and are not closed to public access or commercial use like some of Melbourne’s water supply catchments. Activities occurring in the catchments include agriculture, aquaculture, mining, forestry, industry, regional cities and towns, transport infrastructure and recreation. The hazardous events are documented and reviewed in the storage and irrigation area risk assessments.

During 2024/25 GMW recorded five incidents that had the potential to affect the quality of water delivered to an urban Water Supplier. All these incidents were for high levels of BGA and are described in Table 1. GMW notified the relevant urban Water Supplier in each instance, in addition to regular sharing of laboratory results.

GMW continued to work with urban Water Suppliers and other catchment partners to minimise the impact to water quality from incidents and activities that occur within GMW’s region.

Blue-green algae management

Management of BGA by GMW is a key program that addresses a common risk to the supply of safe water. The Blue-green Algae Circular (the Circular) issued by Department of Energy, Environment and Climate Action (DEECA) provides the main guidance for BGA preparedness and response. High levels of BGA regularly occur in waterbodies within GMW’s region and have the potential to affect drinking water supplies.

In accordance with the Circular, GMW is the Local Water Manager for BGA risk management in its storages and water supply network and the Regional Coordinator for BGA preparedness and response. Algae in the River Murray is primarily monitored and managed by New South Wales authorities, in partnership with GMW and other Victorian agencies via the Murray Region Algal Coordinating Committee.

GMW continued to engage with a range of stakeholders on BGA management, including hosting the pre-season meeting on 27 November 2024, which is a requirement of the Circular.

In 2024/25, 14 separate BGA warnings were issued by GMW based on recreational guidelines, with five of these warnings for water sources also used by urban Water Suppliers (refer Table 1). In addition to the five new BGA warnings, warnings at Lake Eildon and Lake Nagambie/Goulburn Weir (confined to the east backwater near Kirwan’s Bridge) first issued in 2023/24 extended into 2024/25.

Actions undertaken for each warning included notification to affected urban Water Suppliers, customers and stakeholders via phone, email, SMS or letter; advice to the public via signage, media release, website, telephone hotline and social media; and additional surveillance and monitoring.

GMW advised DEECA and DH regularly via the BGA Status Report of all BGA results for GMW managed waterbodies. DH and DEECA were also notified via email when BGA levels exceeded a recreational trigger.

BGA factsheets and information on the current BGA warnings for GMW’s storages and irrigation areas can be found on the BGA Warnings webpage www.gmwater.com.au/bluegreenalgae-alert/.

In addition, the public can access warning information by calling GMW’s BGA Hotline on (03) 5826 3785, contacting GMW directly during business hours on 1800 013 357 or emailing reception@gmwater.com.au

Table 1 : Blue Green Algae Recreational Warnings issued by GMW in 2024/25 for water sources used by urban Water Suppliers

Italics indicates warning periods that commenced in 2023/24 and continued into 2024/25.

Safe Drinking Water Regulation 17 –

c. A summary of every written undertaking by the water storage manager accepted by the Secretary under section 30 of the Act.

f. Details of any exemption granted to the water storage manager under section 8 of the Act and any condition imposed in relation to any exemption.

 There were no exemptions or undertakings in place with DH during 2024/25

Safe Drinking Water Regulation 17 –

d. A summary of the findings of the most recent risk management plan audit and any issues that the approved auditor raised during the risk management plan audit.

The Secretary to the Department of Health did not require GMW to undertake an audit of its risk management plan during the 2024/25 reporting period. The most recent audit was undertaken in 2023 and the only Opportunity for Improvement (OFI) identified has yet to be discussed with DH, see Table 2.

Table 2: OFIs arising from 2023 audit

Safe Drinking Water Regulation 17 –

e.  (i) a summary of the process by which the water supplied by the water storage manager is disinfected or treated and any other processes applied to the water by the water storage manager, and any issues arising out of the application of those processes; and

e. (ii) a list of all the chemicals and other substances, and any processes, used by a water storage manager to disinfect or treat the water supplied, or to be supplied, by it for drinking purposes;

GMW does not disinfect, treat, or process any water supplied to its customers. Water supplied by GMW is not suitable for direct human consumption and GMW customers are advised of this (see also Section 3.2

GMW has prepared water quality risk assessments for each GMW storage and irrigation area. All assessments are regularly reviewed with input from relevant urban Water Suppliers. During 2024/25, risk reviews were undertaken for seven storages and two irrigation areas. All changes to risk level ratings were documented and communicated to urban Water Suppliers.

GMW continued to implement key programs to manage the identified risks to water quality. Examples of the activities undertaken by GMW during 2024/25 are provided in Table 3.

Table 3: Key Program activities

No water supplied by GMW is suitable for human consumption or related uses without first being properly treated. GMW has a Customer Information Statement to advise customers of the non-potable nature of the water supplied, which is provided to new customers and periodically to all customers via newsletters. It is also located on the GMW website www.gmwater.com.au.

Customer invoices, licences and leases include a statement about the non-potable nature of the water supplied by GMW. The public and stakeholders are also made aware via statements included in BGA media releases and signs on non-potable water taps at GMW sites.

This report and further information is available from our website www.gmwater.com.auor by contacting:

Goulburn-Murray Water
40 Casey Street
PO Box 165
Tatura VIC 3616

Free call: 1800 013 357
Standard call: (03) 5826 3500

Email: reception@gmwater.com.au 

Table 4: Urban Water Supplier Offtakes where GMW is the Water Storage Manager

¹ All water supplied by GMW is raw i.e. not treated

² Regulated water as defined under the SDWA i.e. water supplied by Water Suppliers that is not intended for drinking but could be mistaken as drinking water

³ South West Loddon Pipeline is managed by GWMWater