Moving or flood-proofing the village of Perth-Andover would cost the provincial government about $7.5 million, according to a report released Friday.
The estimated cost for similar measures in Tobique First Nation is $700,000, the report to government concludes.
"The risk to Perth-Andover and Tobique First Nation is relatively high with a flood event occurring about every five years over the past decade," the 16-page report states.
And it’s expected to get worse due to a recent warming trend that contributes to the early break up and movement of ice, the Perth-Andover and Tobique First Nation Mitigation Study predicts.
"Thus it is reasonable to consider relocation of the most seriously affected residences (those that experienced main floor damage) and to consider flood-proofing other affected properties."
Flooding in March caused a state of emergency to be declared in Perth-Andover, with about one-third of the western village’s 1,770 residents being forced to leave their homes.
The flood level was roughly 1.5 metres higher than the last major flood in 1987.
Many homes and businesses were damaged, along with the local hospital and high school.
Residents of the Tobique First Nation were also evacuated and transported to safe locations.
How to prevent, reduce impact
A committee made up of representatives from the Tobique First Nation, the Village of Perth-Andover, citizens of Perth-Andover, NB Power and government officials, has been looking into what could be done to prevent or mitigate the risk of similar floods in the future, or reduce the impacts of such floods.
The committee identifies three key options in its report — adaptation, mitigation and relocation.
The Alward government has said a relocation program could be an option.
Of the 83 residential properties affected by flooding in Perth-Andover, only 72 would be candidates for relocation or flood-proofing because the other 11 have been, or will be demolished, the report found.
The estimated cost of relocating a house to a serviced lot within the municipality is $100,000, it states.
In Tobique First Nation, there are "a few homes" that could be relocated, given the availability of suitable sites. "It is possible, however, through other proposed mitigation initiatives to avoid the need for relocation."
Dam not the cause
Although many area residents blame NB Power’s Beechwood Dam, located 26 kilometres downriver from the village, for causing the flood, the report suggests heavy rain, warm weather and ice jams are to blame.
"Dam operations are not a significant contributing factor to ice jam formation," the report states. And there is "little if any opportunity" to prevent or mitigate ice jams through dam operations, it concludes.
A consultant found removing piers, located about 4.5 kilometres from the dam, and dredging the St. John River might help reduce the formation of ice jams and subsequent flooding.
But the pier removal, which would take a year and cost about $1.5 million, "will not likely result in any significant reduction in flood potential" in Perth-Andover and Tobique First Nation, the report states.
And the river doesn't seem to have any obvious signs of high spots to be dredged.
Need for further study
Another consultant identified three ice management options that could reduce the risk of ice jam flooding.
It found ice control measures can be effective, but are costly and may pose significant environmental impacts.
Ice growth suppression measures are less costly, but are very sensitive to environmental conditions and the timing of their implementation, making their effectiveness every year unlikely, according to the consultant.
Meanwhile, ice cutting and breaking measures can be effective for certain conditions with the right timing, but they too are sensitive to environmental conditions, the consultant found.
All three options will be studied in greater detail, with a follow-up report expected in mid-October.
The report also concludes the provincial government needs to enhance the monitoring and forecasting capacity to provide real-time flow and water level monitoring; and risk assessments of ice break-up, movement and ice jam formation.
The review committee recommends further investigation of that with a one-time cost of $400,000. The annual operating cost is yet to be determined.