That's actually a funny mention for water element being his secondary element because Uzumaki can mean whirlpool. So water being his second affinity is a possibility.i guess kishi never intended to make him from any reputed clan
he just picked the name cuz it looked beautiful
minato - harbor
nami - wave (sea wave)
kaze - wind .
namikaze - wind from sea-wave
that is the reason why naruto have the wind affinity
and i bet if another nature was intended for naruto it would have been water .