There’s no avoiding it anymore. The emerald ash borer is in Riverside and here to stay.

This year the pest showed up in traps provided by the Illinois Department of Agriculture in three different areas of the village and officials now expect to see ash tree mortality begin to climb as a result of the emerald ash borer by 2013.

“The bottom line is we can expect to start seeing some level of mortality by the end of 2013,” Riverside Forester Michael Collins told members of the village board during their regular meeting Monday night.

“And then once we start seeing that, the mortality or attributed deaths will increase exponentially as the years progress.”

That means two things – the village of Riverside can expect to lose scores of ash trees in the coming years as they succumb to the emerald ash borer, and the village can expect the removal of those trees and their replacement to be an expensive proposition.

As far back as 2008, when Riverside first began to confront the possibility of an emerald ash borer infestation, Collins estimated that to remove and replace every one of the 1,100 ash trees on public lands in Riverside would cost the village $1 million.

“Overall, it’s going to be a tremendous expenditure,” Collins said.

Since that time, Collins has done some targeted removal of ash trees. Thirty ash trees were removed this year as part of a federal grant and 70 poor-quality ash trees have been removed since 2008 to help slow the spread of the emerald ash borer in Riverside.

That cost does not include the amount of money that will be expended by private citizens who will have to cut down any ash trees infested by the emerald ash borer. And, according to village law, once a tree on private land has been identified as being infested, it must come down.

If the resident refuses to comply, local law allows the village to take the tree down itself and bill the resident for the cost and place a lien on any property where restitution isn’t made. The village follows the same procedure when trees are diagnosed with Dutch elm disease.

“It’s going to be a tremendous burden for ourselves monetarily and for our residents for years to come,” Collins said.

For the past three years, Riverside has attempted to gauge the emerald ash borer’s presence in the community by placing purple traps (so called because of the traps’ color) in forested areas throughout the village.

In 2010, one adult emerald ash borer was found in a trap placed in the park area along the Des Plaines River at Blackhawk and Riverside roads. However, there was no evidence that the pest had made itself a home in any of the several ash trees in that area.

This fall, the Illinois Department of Agriculture, which provides the traps to the village, reported that two adult emerald ash borers were discovered in three separate traps. Those traps were located not only in Indian Gardens along the Des Plaines River but in two locations in the north end of the village, near the intersection of Repton and Southcote roads and at Uvedale and Southcote roads.

Collins has recommended dealing with emerald ash borer infestation as it progresses and is not calling for clear-cutting ash trees in the village all at once. That approach will allow Riverside to maintain its large ash trees for a longer period of time and allow the village to monitor advances in treatment of the pest.

At the same time, Collins is not in favor of treating ash trees with chemicals to slow the emerald ash borer, saying he’d rather put that money toward the reforestation effort.

“I would rather see us invest in new trees for tomorrow and take this as a great opportunity to take 10 percent of our current inventory that we stand to lose and turn that into a positive 10 percent, get more species diversity and buffer our tree inventory against these kinds of losses in the future,” Collins said.

The village board, as a result of Monday night’s discussion of the emerald ash borer, also agreed to hold off on slashing additional money budgeted in 2012 for tree trimming. The board had already agreed to slash funding from $70,000 to $50,000 and were considering cutting that amount by another $12,000 in order to help fund raises for non-union village employees.

The village didn’t provide any money for tree trimming in 2011. Trustee Ben Sells called for the village to hold the line on tree trimming at $50,000 for 2012. Trustee James Reynolds agreed.

“It’s not a huge amount [of money] … Certainly this is an important issue for the village,” Reynolds said.