Waste water from a building site in a Sai Kung country park enclave is polluting a stream rich with wildlife including creatures known as "living fossils", residents and scientists believe.
Environment officials carried out inspections at Tai Tan village, which straddles both Sai Kung east and west country parks, after residents last week reported seeing cleaners sweeping waste water into the freshwater stream.
The officials vowed to keep close tabs on the area after the residents traced sludge in the stream uphill to a muddy ditch at the construction site, where 20 village houses are being built on one side of a single-track road adjacent to the stream.
The area is part of one of 54 enclaves which the government is drawing up plans to protect, either through zoning or by folding them into country park: a process that is proving controversial amid clashes between conservationists and landowners, who feel their rights are in jeopardy.
"The whole village is a mess," one Tai Tan resident said. "The builders stopped sweeping and pumping on Saturday after they were questioned by residents."
Builders told villagers water drained from the site was clean.
Filled with rich wildlife including egrets, turtles and kingfishers, the stream has been designated as ecologically important by the Agriculture, Fisheries and Conservation Department. The site where the building work is taking place has been approved for village development, the Lands Department said, but some Tai Tan residents fear that construction of the 20 village houses will pave the way for more environmental destruction.
Local geologist Kevin Laurie said he was concerned about Tai Tan's mudflats, the last place in Hong Kong that the Lingula anatina is found.
The lingula is a type of brachiopod, a shelled marine creature. Because it has evolved little in the last 500 million years, it is sometimes known as a "living fossil" and was featured in Cambridge paleontologist Professor Richard Fortey's 2011 BBC television series and book Survivors: Nature's Indestructible Creatures.
But, Lauries said "no one in government has bothered to brief the Town Planning Board" on the creatures before it gave permission for development.
Environmental Protection Department inspectors last week found no waste water discharge.
"The stream was clear and there was no sludge," a spokeswoman said. "But we have advised the contractor to take measures to ensure any waste water … is properly treated and disposed of."
She said the department would continue to monitor the situation. The contractor could not be reached for comment.
About 70 per cent of the enclave belongs to the government. The rest is privately owned.
Tai Tan and three nearby villages are part of a 70 hectare development permission area, drawn up by planners to control building while a zoning plan for the enclave is drawn up. The government is expected to draw up plans for about half of the 54 enclaves as part of a process that began after outrage over unauthorised development in Sai Kung in 2010. The rest could be folded into country parks. But some want all enclaves protected.
John Wright, secretary of the Friends of Sai Kung concern group, slammed the planning rules as "laughable" and said: "Tai Tan is just one example where a group of villagers and developers driven by greed … are ruining the country parks."