Why change Wanganui’s spelling to Whanganui? Surely not because whanganui means ‘large harbour’? Where’s the large harbour?
Looks like a wide upside-down river to me.
Let’s steer clear of both warring factions and, in the interests of accuracy, go for a new name altogether: Waipara North.
Wai= water.
Para=sediment, mud.
Martinborough Musings 
Aue, aue!
There’s much truth in what you say John. We in Whanganui are blessed with para in plenty.
However!…
Whanganui also means big heaven, big bay and – most notably – BIG MOUTH. Our esteemed mayor – by indulging in his usual endearingly obnoxious and abusive ways – has lent considerable verisimilitude to the the linguistic claims of the tangata whenua.
😦
I elicited a lot of comment about this debate here:
http://mywitsend.co.nz/wanganui/580
“Ko au te awa, ko te awa ko au”
🙂