Island pool water polluted – council

People are warned not to paddle in the ponds of water filling low-lying hollows across Rabbit Island.

Tasman District Council environmental resource scientist Trevor James said testing showed the pools were contaminated.

‘‘The first results have come back and are just over alarm levels for bathing, which is a concern,’’ Mr James said.

The cause of the pollution has not been identified but contamination from biosolid spraying on the island had not been ruled out. Further tests would be carried out.

The council’s reserves manager, Beryl Wilkes, said the island was open to the public and the largest of the ponds had been fenced off. Signs had been erected advising people not to enter the water.

The ponds are a hangover of the 2.7 billion litres of rain which fell over the 1000-hectare island in the four days from December 12.

The coastal Nelson Golf Course also gained unwanted water features in the December deluge which drained enough to enable a return to play on the full course on Wednesday.

Tasman District Council resource water scientist Joseph Thomas said the low-lying lakes would take some weeks of fine weather to drain away.

They were created when the overly charged freshwater table rose through the coastal sands and gravels and filled low-lying hollows. The freshwater lay over the top of the heavier seawater and hence rose and fell with the tide.

Typically rain would soak through the sand and into the lower freshwater table before slowly draining out around the edges of the table.

However, twice daily tidal movement hindered the slow drainage of the ponds, which were forced upwards by the underground tidal rise.

Nelson Golf Course manager Peter Hay said he had never seen water pond on the course to such an extent across the coastal course.

The course was closed for a couple of days after the heavy rain. Greens staff managed to get a truncated 18-hole course operating before more rain at the end of the month recharged the ground water table and the unwanted lakes. Play resumed on a shortened course and returned to the full 18-holes on Wednesday, Mr Hay said.

The flooding had not affected the greens but had seen golfers playing over large stretches of water in the rough and fairways.

‘‘There have been adventurous people wandering into the black water to retrieve balls. Others have waited for the water level to drop.’’

The flooding had impacted on club revenue. ‘‘The timing was unfortunate because it happened when we typically get the most visitors and green fees.’’