New Brunswick's Emergency Measures Organization may need to come up with a new way of rating its floods, says a senior official.

The 2008 flooding of the St. John River is being ranked as a "one in a hundred year" flood, said Andy Morton, deputy director for EMO.

But so was the record-setting flood in 1973, when levels reached 8.63 metres in Fredericton, and the 2005 flood that reached 7.83 metres. The flood stage in the city is 6.5 metres.

The waters of the St. John River reached 8.33 metres in Fredericton in this year's flooding, before beginning to recede. The river is still rising in the southern part of the river's basin near the port city of Saint John, where the flood waters are expected to crest at 5.2 metres — more than a metre above flood level.

"I think we're going to have to come up with a new way of characterizing them," Morton said.

Classifying a flood as a "one in a hundred year" level means that it is only supposed to reach those levels once a century, Morton said.

"It means that each year you've got a one in a hundred chance of having it," he said. But the last 35 years have proven that description wrong, Morton said.

"So I think we need to come up with a better way of doing that."

Morton said Emergency Measures will be discussing with Environment Canada and the provincial Environment Department if there is a better way to classify flood events in New Brunswick.

The 2008 flooding began with the spring snow melt but was compounded when 100 millimetres of rain which fell in the northern part of the province, southern Quebec and Maine funnelled into the St. John River.