Aerial imagery has found hundreds of illegal dams have been built or enlarged in the Adelaide Hills over the past 10 years.
About 400 new dams have been built in the Mount Lofty Ranges, and about 300 significantly enlarged, without approval.
This has occurred despite a moratorium on building new dams in the ranges since 2013.
Hills and Fleurieu Landscape Board general manager Michael Garrod said the organisation was aware of some illegal dams, but he was surprised by the scale of the problem.
“Many of the catchments in the Mount Lofty Ranges were already over-allocated and under some stress, so these new dams that have been built without authorisation will deny water getting to those legitimate dam owners,” Mr Garrod said.
“Capturing water in an illegal dam amounts to water theft.”
There are 22,000 legitimate dams in the Mount Lofty Ranges.
Mr Garrod said, despite the drought putting pressure on water in the Adelaide Hills, there had not been a particular uptick in illegal dams in the last two years.
A single dam in a dry paddock in the Mount Lofty Ranges in 2021. (Supplied: Landscapes Hills and Fleurieu)
The landscape board has been working with landholders to either reduce the total volume of water being captured on a property to the amount before the illegal dam was built or require them to remove it.
Mr Garrod said with drier and more variable conditions, fair and responsible water management was more important than ever.
This photo shows multiple dams on the same Mount Lofty Ranges property in 2022. (Supplied: Landscapes Hills and Fleurieu)
“We have to find new and better ways of storing and using water, building more dams and losing more to evaporation is just a recipe to less water for everybody,” he said.
Given the need for landholders to be resilient to the changing climate, Mr Garrod said using groundwater more might be an option.
“Our groundwater resources are in much better shape than our surface water resources, so that would be a logical change,” he said.
Kangaroo Island dams also in spotlight
Kangaroo Island (KI) was the other hotspot with about 350 unauthorised dams also detected, after changes were made to dam building in 2017 when the current water plan came into force.
AgKI chair Peter Cooper said the organisation was aware of the issue.
Mr Cooper said before 2017, dams on Kangaroo Island that held less than 5 megalitres did not require approval, so some people had built dams not realising that rule had changed.
“So this process has been a lot about the education about how the regulations work and what needs to happen into the future,” Mr Cooper said.
Dams were drying up across the Mount Lofty Ranges earlier this year. (ABC South East SA: Caroline Horn)
Mr Cooper said given the lack of groundwater, dams were vital for primary production on the island.
“Farmers want to be spending profits on improving water infrastructure and having the ability to be more resilient in years like this to come, so that’s going to be difficult to juggle with the new dam compliance laws,”
he said.
The Kangaroo Island Landscape Board has written to landholders who built dams that were not authorised but would have been if they had sought approval to explain what they should have done.
However, the 10 landholders who built dams that would not have been approved have not yet been contacted.
“We (AgKI) have asked that that be delayed until we have an opening to the season to reduce the stress farmers need to have upon them in the season that we’ve had,” Mr Cooper.
Sustainable landscapes manager Jo Sullivan said the landscape board had never intended to start any compliance work until the season had broken.
She said the main motivation for the work was to improve the understanding of the rules.
“We really encourage the community to contact us if they have questions or concerns about construction of dams or water availability on their property,” Mr Sullivan said.
Compliance officers are continuing to review dams, and an automated change detection system is being developed to allow the landscape boards to identify new and enlarged dams more easily than in the past.
