Lakehead Region Conservation Authority to update 30-year-old flood plain maps

Officials with the Lakehead Region Conservation Authority are updating the official maps, models and records of one of the major flood plains in the city.

The LRCA will be holding an open house Thursday in Thunder Bay, Ont., to show the updated maps for the Neebing River flood plain and a surrounding buffer zone, along with any changes to building and permitting regulations for the flood plain. The mapping hasn't been updated since the mid-1980s, shortly after the Neebing-McIntyre Floodway was built.

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"What it really means is looking at updates to culverts and bridges and land use changes and creating a new digital elevation model," Tammy Cook, the chief administrative officer for the LRCA told CBC Thunder Bay's Superior Morning, adding that updates to documentation of the flow of the river are also being done.

The work will culminate with "creating a ... model that basically calculates how high is the water elevation throughout the watershed, and that's put on maps," Cook said.

This study and re-mapping follows a similar exercise done for the McIntyre River flood plain done in 2015.

The conservation authority owns lands to serve as flood protection along the Neebing and McIntyre Rivers, as well as the Neebing-McIntyre Floodway. Those measures ensure that developed parts of the city, like much of the Intercity area, are protected from rising waters in the nearby watercourses.

Updates to technology over the past 30 years also mean much more accuracy in how the area is mapped, Cook said, adding that traditional surveying is still used.

"So we have a very accurate representation of what is on the land," she said.

The Neebing River flood plain itself hasn't changed too much in the past 30 years, she said. Most of the differences in the new maps will be the level of detail they show.

"Thirty-three years later, you want to make sure that you can be confident going into the future so we wanted to update our mapping, partly because we had updated funding available," she said, adding that the City of Thunder Bay and Municipality of Oliver-Paipoonge helped with that funding.

Public meeting at LRCA headquarters

The new maps are scheduled to officially take effect Apr. 26.

Prior to that, the conservation authority is holding an open house so people who live or have property near the flood plain can "come and speak to the expert staff we've got and the consultants that will be on hand as well," said Ryan Mackett, the LRCA's public relations officer.

The meeting will take place on Mar. 29 at the conservation authority's headquarters and runs from 4-8 p.m.