Over the last 40 years its Tunnel and Reservoir Plan (TARP or Deep Tunnel project) has seen the construction of more than 100 miles (160km) of sewer tunnels.

More recently the city saw the completion of its Albany Park tunnel, a mitigation project following devastating flooding in local neighborhoods over the last 10 to 15 years.

Choosing Chicago to host is convenient timing. Following a particularly harsh winter the National Oceanic and Atmospheric Administration (NOAA) warned in March that spring will bring “historic and widespread flooding”.

Nearly two-thirds of the lower 48 states face an elevated risk for flooding through May, with the potential for major or moderate flooding in 25 states, according to NOAA. Plus a majority of the country is “favored” to experience above-average precipitation this spring, increasing the flood risk.

The organization reported record flooding already in the upper Mississippi and Missouri River basins, attributing this to rapid snow melt combined with heavy spring rain and late season snowfall in areas where soil moisture is high. In some areas, ice jams are exacerbating the flooding.

Additional spring rain and melting snow will prolong and expand flooding, especially in the central and southern states. As this excess water flows downstream through the river basins, the flood threat will become worse and geographically more widespread.

The upper Mississippi and Red River of the North basins have received rain and snow this spring up to 200 per cent above normal. Red River floods are an unfortunately familiar sign of spring to many residents in Minnesota, North Dakota and Manitoba—into which it flows from the US—and as ever officials are on alert on either side of the border as the snow melts.

It’s no coincidence the Tunnelling Association of Canada is organizing its biennial workshop in Winnipeg, Manitoba, on the theme “The Use of Tunnelling Technologies and Underground Space for Stormwater and Flood Control”.

Vulnerable cities, towns and neighborhoods need fewer sandbags and more resiliency, and these conferences could be a step in the right direction.

Keeping tunnels in the flood mitigation conversation is imperative to maintaining economic security, clean rivers and lakes, and healthy communities.

We hope to see you there.