St Kilda residents say rising salt water is flooding septic tanks, but the state government is not helping

St Kilda residents are fearing for the future of their town, as rising salt water floods septic tanks and eats away at concrete.

Septic tanks are failing and having to be pumped out at St Kilda, where residents fear rising hypersaline groundwater from the nearby salt fields is swamping their town.

Dismayed at the lack of state government action, the St Kilda Mangroves Alliance of concerned locals, scientists and conservationists met at the boardwalk trail on Thursday to sound the alarm.

At the northern end of the suburb, Kevin Collins, 80, witnessed the death of one large 32-year-old gum tree in autumn and now, another is showing signs of distress.

St Kilda residents Lindsay Virgo, Peri Coleman and Kevin Collins at the pink lake. Picture: Roy VanDerVeg

His septic tank struggled in the wet conditions and had to be pumped out, while the kerb in the town is crumbling, having been “eaten away” by rising salty groundwater.

Mr Collins is upset about the loss of mangroves and saltmarsh, especially ongoing threats posed by heavy rain mobilising salt in the leaky ponds, as reported last month in The Advertiser.

“I’m not impressed, there’s been a lot of talk and there hasn’t been much action,” Mr Collins said.

“Mainly I’m concerned about the salt water coming underneath the town. The Department of Mines has not been monitoring what’s going on.”

St Kilda and Surrounds Progress & Tourism Association president Lyndsay Virgo said as many as five residents had reported problems with saltwater encroaching on sewage tanks.

“Concrete and salt water are not nice friends, and consequently, there’s a concern that the salt water will have an effect on the concrete structure of the actual tank,” he said.

“And over time, they’ll start to collapse and then the contents of your septic tanks will leach straight into the ground, which is not a nice thing at all.”

St Kilda on Thursday, where locals fear the rising salt water is affecting the groundwater. Picture: Roy VanDerVegt

The Environment Protection Authority “continues to monitor” groundwater and surface water habitats across the saltmarsh and mangroves and “has not seen evidence of any new leakage or movement of hypersaline groundwater into the saltmarsh following the partial filling of Section 2 ponds from the recent winter rains”.

The state government said prompt action stabilised the site and regulators would respond to any evidence of risk to the environment.

“The St Kilda area has been historically impacted by salt due to its location,” a spokeswoman said. “Government agencies met with residents … and continue to undertaking monitoring.”