Report on the continued growth of private dams in the Moorabool Catchment
The issue of the high number of private dams in the Moorabool Catchment and their impact on flows within the river has been recognised for many years. The 2004 Sinclair Knight Mertz study Moorabool River Water Resource Assessment identified that one the "Key Issues in the Catchment" was the "Impact of farm dams on flows". https://www.ccmaknowledgebase.vic.gov.au/resources/R05_Final_report_d1.pdf
Modelling done in the report produced the following table of supply demands:
Newer modelling has allowed for more refined figures, although studies to determine the impact of private dams over different climate scenarios are ongoing.
Figures from the annual Victoria Water Accounts have been alarming. Private dam volumes in the Moorabool Basin compared to inflows are the second highest in the state. The stated figure of 20,236ML in 2017-18 was equivalent to the capacity of Barwon Water's West Barwon Reservoir.
A graphic from a 2020 study titled Investigation of trends in farm dam development over time. (Department of Environment, Land, Water and Planning - Jordan, P., Shepherd, D., & Race, G. (2020)) is illustrative of how large the impact of private dam development is within the Moorabool Catchment. It compared subcatchments in 3 different basins. Franklin Creek in Gippsland, Love Creek near the Otways, and Woollen Creek in the Moorabool catchment which feeds into Lal Lal Reservoir. The volume of private dams compared to km2 of Woollen Creek was 8 to 10 times that of the other subcatchments:
In the recent Central and Gippsland Regional Sustainable Water Strategy completed last year, both the Moorabool and Maribynong catchments were acknowledged as private dam hotspots and an action adopted which committed to:
Review of water resource risks in small, dry, peri-urban catchments
Southern Rural Water will lead a project over two years to review resource risk and share evidence and reporting to build a shared understanding with communities on the risks, consequences and mitigation options we can use to address the increasing effects of small catchment dams. This project will focus on the upper Maribyrnong and upper Moorabool catchments (including tributaries) as identified hotspots, but recommendations from this review may be relevant to other catchments.
However the rationale was based on the belief that the issue was mainly due to "land uses are changing between agriculture and urbanisation". This was not what PALM supporters were observing on the ground. Downstream irrigators and farmers who are reliant on the river for stock and domestic needs had expressed concerns that large private dams were being developed in the upper catchment.
The group resolved to do its own study of where private dam development was occurring, and to see if it exceeded the growth rates described by DEECA. We were assisted by anonimised data from SRW showing licenced dams within the catchment.
Google Earth and its capacity to compare historical satellite imagery was used to note new and enlarged private dams developed, particularly over the last decade. It allowed an approximation of volumes based on a recognised formula for Victorian dams. In total this ultimately involved over 200 dams the majority from 2012 onwards, and many hours of volunteer time and effort.
PALM's report titled The Dammed Future of the Moorabool River - Testing arguments over the trajectory of private dam construction in the Moorabool River Catchment was sent to the Water Minister, Southern Rural Water and other relevant agencies in March 2023. PALM acknowledges within the document that:
This is a community driven and created discussion paper. While every reasonable endeavour was made to be as accurate as our limited resources permit, the report is presented as a basis for a policy review of how private dam development is managed within Victoria.
PALM does not imply, and no reader should infer, that any landowner within any areas covered by this investigation has enlarged or constructed a dam in breach of the rules applicable at the time of enlargement or construction.
From PALM's perspective there were a number of key points.
- It appears the annual increase in new private dam volumes over the last 10 years was triple that predicted by DEECA studies.
- Quite a number of the recent dam installations of significance appeared to coincide with either windfarm development or plantation harvesting.
- A concerning number of dams were constructed on watercourses as defined by the government dataset (https://discover.data.vic.gov.au/dataset/vicmap-hydro-1-250002)
It is the last point which is most troubling to PALM. A landholder digging a small dam in the corner of a paddock to provide stock needs is unlikely to impact the river. However in a narrow catchment such as the Moorabool virtually all watercourses contribute flows to the Moorabool River. The placement of new and enlarged dams on those watercourses will likely have a direct impact. The Water Act specifies that such dams should be licenced by the responsible authority. Southern Rural Water has since indicated to PALM that there are currently a number of dams of concern and that investigations are being conducted.
Monitoring and compliance is of course a factor in the proper management of water resources, but this does not address the inherent ambiguities within the current licencing system. As stated PALM's primary objective has been for the report to provide a "basis for a policy review of how private dam development is managed within Victoria". Part of that review must include addressing the fragmented approach to the authorising of new and enlarged private dams. Currently a landholder seeking to install a catchment dam in the system may have to approach 3 different authorities; Southern Rural Water, Moorabool Shire and the Corangamite Catchment Management Authority. This needs to be reformed.
Next, the ambiguities around what constitutes a watercourse need to be resolved. While the Water Act appears to be clear on what it considers a watercourse, and these appear on maps used on Victorian Government planning portals, they remain open to interpretation by regulatory staff. This amplifies confusion for landholders, and for other interested parties, and needs to be addressed in a manner which will protect the Moorabool.
Finally the education of landholders regarding their obligations and the potential impacts of certain activities, especially those who may not be aware of how flow stressed the Moorabool system is, must be the responsibility of those managing the system, particularly Southern Rural Water.
PALM considers that there must be a moratorium on new private dams in the system until these issues are resolved. We all need to face up to the fact that the catchment’s water has been massively over extracted for years and we are killing the river. It may well mean urban water users have to accept they will have to pay a bit more for water to be sourced elsewhere. It may also mean that landholders consolidate dams on their properties and construct reticulated systems to get water over their holdings just as some are already doing. PALM would fully support government initiatives to restructure the way water is used in the catchment such as assisting with reticulation costs.
If the government, the agencies, and the community get on the same page then this river just may have a fighting chance.
ABC have published a story on the report. It can be accessed here.
Introducing Paulina Gutierrez Ramos - PhD Student working on the Moorabool River
It is with great pleasure PALM introduces Paulina Gutierrez Ramos.
Paluina in her second year of her PhD study looking at the Moorabool River Catchment. Based at the Deakin University, School of life and Environment, Center of Rural and Regional Futures Paulina's main focus is on catchment health and water forecasting.
Paulina has kindly provided the following bio and abstract:
Project Sponsor: Barwon Water and Corangamite Catchment Management Authority
I grew up in the city of Leon, in Mexico. I have always been interested in science, which led me to pursue studies in Biology and Environmental Science. During my bachelor studies, I was recipient of a scholarship in 2006 and had the amazing opportunity to come to Australia sponsored with an international scholarship, to attend Deakin University.
After finishing my undergraduate studies in Mexico, I migrated to Australia and continued studies in secondary school teaching. I worked as a high school teacher for 10 years. Due to my passion for science and sustainability, I completed a Master in Sustainability doing a project on sustainable regional development in both Mexico and Australia; I completed my research with recognition for academic excellence.
Currently, I am on the second year of my PhD project. My research focuses on catchment health and water forecasting. I hope my research will be useful for water managers, landowners and community organisations of the region and for catchment managers. At the end of my studies, I plan to pursue a career in the water management industry.
Title of PhD Project: Environmental flows in the Moorabool River
A significant proportion of the potable water used for human consumption comes from surface water, rivers and lakes. However, the modification of many waterways has had an impact on hydrological cycles and the functioning of freshwater ecosystems. Australian rivers have not escaped this fate.
In addition to direct, physical alterations, Climate change has an impact on the hydrological regime of many rivers. The uncertainty of different climates poses a challenge for natural resources managers, and preparing an adaptation plan requires consideration of different scenarios and application of water forecasting models.
Hydrological models help to explain the water balance of a catchment. Hydrologist use rainfall-runoff models to predict river flow and forecast the effects of land use changes, such as urbanization, land clearance and agricultural farm dams. The hydrological impacts of land-use change to streamflow, specifically alterations caused by interception of water via farm dams, is a topic of increasing scientific interest.
The influence of water trapping by farm dams on stream flows within the Moorabool Catchment, and many other catchments in Australia and overseas, is currently unknown. Given the potential cumulative impact of farm dams to trap significant volumes of water, thereby reducing runoff and subsequent river flow, my research aim is to quantify the distribution, morphological characteristics and number of farm dams in the Moorabool catchment. The morphological characteristics will include surface area and storage capacity. I will then model the correlation between farm dam water storage to stream run-off on an annual basis.
Bolwarra willow removal works - first stage complete
The first stage in the willow removal at Barwon Water's Bolwarra Wier has been completed.
An extensive willow infestation at the top of the wier has been removed and burnt onsite. Any regrowth with be dealt with over the coming months before further works commencing later in the year.
Funded by Barwon Water's Living Moorabool contribution and overseen by the Corangamite Catchment Management Authority the project will see the restoration of native species to the site and the introduction of walkways for the public.
Images courtesy of the Corangamite Catchment Management Authority.
While it may have taken a while it is really refreshing to have Barwon Water stepping up and taking ownership of weed management on sites like these. The willows here would have been contributiing to infestation downstream of the weir for decades.
There will obviously be a need for long term management of the site by Barwon Water have indicted a management plan is being formulated across all their sites, Bolwarra Weir included.
A thank you also goes to the CCMA for project managing the works. It is alway good to see funding directed to making a real difference on the ground.
A koala dream for the Moorabool River in Victoria
PALM would like to acknowledge and applaud a focus on the Moorabool River by the Koala Clancy Foundation.
The article speaks to the importance of river red gums in supporting koala populations during heatwaves and times of drought.
SRW urged to increase monitoring on unlicensed dams
The Geelong Times has run a front page story on PALM's call for better monitoring of catchment dams within the Moorabool River Catchment.
The catchment has one of the highest ratio of total private dam capacity compared to inflows in Victoria. The volume is equal to that held by Barwon Water's West Barwon Dam in the Otways.
Private dam development is accelerating putting further strain on the State's most flow stressed river. Without better controls, monitoring and compliance the growth in such dams will further erode small gains in environmental flows that have been secured for the river.
PALM is currently finalising a study looking at the last decade of dam growth which it hopes will inform the following action within the latest Central and Gippsland Region Sustainable Water Strategy
Action 4-13: Review of water resource risks in small, dry, peri-urban catchments
Southern Rural Water will lead a project over two years to review resource risk and share evidence and reporting to build a shared understanding with communities on the risks, consequences and mitigation options we can use to address the increasing effects of small catchment dams.
This project will focus on the upper Maribyrnong and upper Moorabool catchments (including tributaries) as identified hotspots, but recommendations from this review may be relevant to other catchments.
The online version of the article can be found here:
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