The law says you can lead stormwater into watercourses. This is part of what the council can do with sewerage and stormwater drainage. The council has certain powers in this area, according to the Local Government Act 1974.

You should know that this part of the law was repealed, which means it is no longer in effect, on 1 July 2003, by section 266 of the Local Government Act 2002. This change was made by the Local Government Act 2002, which you can find more information about at https://legislation.govt.nz/act/public/1986/0120/latest/link.aspx?id=DLM174092. This means that as of 1 July 2003, you can no longer do something under this specific part of the law.