Enthusiastic children throwing bread to the ducks have left two South Auckland lakes so polluted they have had to be drained and dredged.
Diggers moved in to clear sludge from the Auckland Botanic Gardens lakes yesterday. Much of the mess was duck poo or festering bread that had missed ducks' beaks.
Almost a million people visit the gardens at Manurewa each year and Jack Hobbs, group manager of the gardens, said feeding the ducks was one of the most popular activities. But it was also a big contributor to murky, dirty water because of the nitrogen that is in duck, goose and swan poo.
When the lakes refill, staff will swap bread for a packet of free grain. Once people get used to the change, grain will cost 20c.
The Auckland Regional Council, which owns the lakes, hopes visitors will take the hint and feed ducks on the grass, where bird poo is a helpful, natural fertiliser.
The birds may thank the council for banning bread. Mr Hobbs said that contrary to belief, bread was not good for ducks' stomachs. "It's not just about the health of the lake it's about the health of the ducks."
Sediment dug from the lake yesterday will be used as fertiliser on fenced-off areas of the gardens.