“Council has replaced the faulty pump as well as the associated pipework and will continue to monitor the system,” she said.

An EPA spokesman said investigators from the department have collected samples of the leak as well as water samples from downstream to “inform if there was any impact to the environment”.

Cowan Creek is located within the Ku-ring-gai Chase National Park

Cowan Creek is located within the Ku-ring-gai Chase National ParkCredit: NSW EPA

“The EPA’s investigation is continuing,” the spokesman added.

This incident is the second time in as many years that the council has been issued with an environmental clean-up order by the EPA after “sediment laden water” was found to be discharging from Norman Griffiths Oval in Pymble into a creek within Lane Cove National Park.

The incident was discovered during upgrade works at the oval involving the installation of a new synthetic turf playing surface at the site.

Friends of Ku-ring-gai Environment president Kathy Cowley said the latest incident was “concerning”.

Kathy Cowley, president of the Friends of Ku-ring-gai Environment community group.

Kathy Cowley, president of the Friends of Ku-ring-gai Environment community group.Credit: Janie Barrett

“Ku-ring-gai is surrounded by three national parks and the council has a strong responsibility to maintain its sites so that no pollution incident occurs,” she said.

“It’s especially important when we’re under so much pressure to build more housing, that’s putting even more pressure on our environment.”

The clean-up order comes after the council – which dubs itself “Sydney’s Green Heart” – released plans to spend $2 million on trees and natural environment works this financial year in its 2025-26 budget.

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