Fighting emerald ash borer will cost Thunder Bay millions: report

City administrators in Thunder Bay, Ont. say they expect dealing with the arrival of the emerald ash borer in the city will cost millions over the next decade.

A report slated to go to council Monday lays out several options for combating the invasive beetle, which destroys ash trees.

• Emerald ash borer confirmed in Thunder Bay: city

• Emerald ash borer report to go before council

• City of Hamilton says emerald ash borer has changed city tree canopy

The report, prepared by city forester Shelley Vescio, shows that simply doing nothingand removing trees after the ash borer kills them would be the most expensive option, costing $7.6 million over the next decade. The report goes on to say that the money would have to be spent, as the trees, once dead, become hazardous.

A combination of treating 50 per cent of eligible city trees in parks and along streets, while removing and replacing others as they die, is being recommended, at a cost of $6.3 million over the next 10 years.

"The earlier you treat a tree, even with emerald ash borer, the more success you have," Vescio said. "So we'll be looking for trees with minimal infestation, minimal defoliation so that the money we invest in those trees is money well-spent."

Vescio estimated that would mean treating about 1,500 trees. To be eligible for treatment, a tree has to be at least 20 centimetres in diameter and in relatively good health.

City in 'pretty good shape'

Years of monitoring the pest, and learning from other municipalities, has put the city in a good position to deal with the beetle's arrival, Vescio said.

"We've been looking for emerald ash borer for I don't know how many years. Now that we've found it, we should be in pretty good shape with being able to treat trees early in the life cycle of the insect, as long as council approves."

The report gives council more options, including treating 30 per cent of eligible trees instead of 50 per cent. That is expected to cost more, as the report notes it's about $800 cheaper on a per-tree basis to treat rather than remove and replace.

In addition, council could chose to remove non-treated trees proactively over the next five years, rather than wait for signs of infestation, but that would mean spending more up front, rather than spreading the cost out.

The report also recommends $550,000 be earmarked in the 2017 municipal budget to treat 150 ash trees and remove another 150, as well as to do more surveying and public education.