A natural, flowing body of water emptying into an ocean, lake or other body of water and usually fed along it's course by converging tributaries.
Data Dictionary for river_cl: http://apps.linz.govt.nz/topo-data-dictionary/index.aspx?page=class-river_cl
This layer is a component of the Topo50 map series. The Topo50 map series provides topographic mapping for the New Zealand mainland, Chatham and New Zealand's offshore islands, at 1:50,000 scale.
Further information on Topo50:
http://www.linz.govt.nz/topography/topo-maps/topo50