Canterbury's Selwyn District Council says signs warning against swimming in a storage pond where a young woman drowned would not have been visible.
The 18-year-old was sucked towards an outlet, which runs into the Waimakariri River, and trapped under water on Wednesday.
Council chief executive Paul Davey says the pond has been a popular swimming spot for families for a long time. Warning signs have been vandalised and would not have been easy to see.
However, Mr Davey says the council is limited in its ability to stop people using the pond and the public must take some responsibility for deciding to swim there.
New signs will be erected and the council may consider building a fence around the pond, he says.