Would any Mudcatters in the New Orleans area care to verify the correct spelling of Lake Pontchartrain ?

Google searches on "Pontchartrain", "Pontchatrain", "Ponchartrain" and "Ponchatrain" all bring up results, although by far the most popular is "Pontchartrain".

I would also be interested to know whether the other spellings are regarded as "incorrect" or whether they are in fact valid alternate spellings.

Murray