The airport had stood empty since its inauguration in 2011 and had become a symbol of the reckless public spending that left a nation buckling under debt.
But with an agreement with Ryanair to operate five flights a week to two UK destinations, the airport that cost an exhorbitant €150 million at last seemed to be on the way to becoming a viable commercial venture.
However, according to a report in El Confidencial the airport operators agreed to pay the Irish budget airline €600,000 ($638,000) a year in return for flying to Castellón.
The digital newspaper claimed the airline pledged to offer 60,000 seats a year to the destination, meaning each seat is subsidized with €10 from the airport operators.
The airport is run by Canadian owned SNC-Lavalin who won a contract to operate the airport from the Valencian regional government.
According to El Confidencial report SNC-Lavalin were paid €6 million to take over the airport, have a budget of €25 million of public funds to invest within the next ten years and don't have to pay the Generalitat any profits until they exceed 1.2 million passengers a year.
However, when contacted by The Local, Ryanair denied that the airline was paid to fly to Castellón.
"This is untrue. Ryanair does not receive any such payment. We negotiate commercial agreements with our airports, which we do not comment upon," said a Ryanair spokesman in an email.
The entire airport project has been plagued with difficulties and scandal since its inception.
It initially failed to get permits to allow air traffic when it emerged that the airstrip was too narrow and had to be dug up and widened.
Despite huge amounts being spent on advertising – an estimated €30 million was spent on a package of sponsorship deals – there seemed little to tempt airline operators to the airport and it was suggested that the "white elephant" be converted into a race track or shopping centre.
The man behind the development, the former president of the PP in Castellón Carlos Fabra, has been jailed for tax fraud. Towering over the terminal is a 25 meter high statue that cost €300,000 and represents Fabra.
However, it is widely considered to have brought a boost to the region, opening up a relatively undiscovered part of Spain to tourism.