Environmentalists are alarmed by Sydney Water's plans to rectify erosion along Boundary Creek in Penrith.

The Land and Environment Court ordered the utility to construct a durable retaining structure to halt erosion, attributed to effluent discharge from a sewage treatment plant.

But critics argue the proposed concrete walls could severely impact platypus habitats. 

“If we concrete up any creek system, it's going to stop platypus being able to burrow and forage,” said aquatic ecologist Michelle Ryan, noting the confirmed presence of platypus in the creek since 2010. 

Despite this, the species' conservation status did not influence the court's decision.

Sydney Water says it prioritises the platypus's safety, and will collaborate with experts for the animal's protection.

Lisa Harrold from the Mulgoa Landcare Group highlighted the risk to potential breeding grounds and urged Sydney Water to seek alternatives that avoid using concrete. 

“We're learning more about [the platypus], but are we going to wipe out that potential by...pouring concrete over habitat?” she says.

“Sydney Water can do better.”

More details are accessible here.