Duluth, Minnesota is a sea-port city located on Lake Superior's westernmost tip. Home to four colleges and more than 84,000 year-round residents, this small city is one of Minnesota's most popular tourist destinations. Each year, an estimated 3.5 million people visit the city to sail on the lake, explore the surrounding steep and rocky bluffs, and relax in the vibrant downtown area along the waterfront ("Duluth Facts"). In the summer of 2012, heavy rainfall caused the most severe flood on record for the City of Duluth, MN. In just two days, more up to 10 inches in some areas inches of rain fell on already saturated soils. This record breaking storm bloated the streams that cut through the city, washing out roads, carrying debris, displacing zoo animals, and blowing out culverts as water rocketed down Duluth's steep slopes and flowed into Lake Superior (Czuba et al., 2012).
The U.S. Coast Guard Documents Duluth Flooding.
Courtesy of: Petty Officer 1st Class Matthew Schofield
As the flood waters began to subside, the full extent of the damages incurred by the city were revealed. Early estimates for the cost of this flood event were placed at over $100 million dollars. Just weeks after the flood ravaged the area, Duluth, and the nine counties that make up Minnesota's north shore were declared a federal disaster area (Czuba et al., 2012). Although federal funding covered approximately 75% of the costs to clean up, repair, and restore much of the infrastructure damaged by this flood event, little funding was allocated to the lower income families who also suffered significant losses. Just a year after the flood waters ravaged the city of the Duluth most damaged infrastructure had been rebuilt, erasing many of the large physical scars left on the face of the community. However, 10-15% of homes were still in various states of disrepair, with many homeowners struggling to find ways to finance the necessary repairs ("Flood-ravaged Duluth, northeast Minnesota, still recovering a year later").
Recognizing that achieving long-term resilience for the community would depend on finding a low-cost and effective strategy for reducing flood losses, the city of Duluth sought guidance from NOAA's Coastal Services Center. With the help of city staff, the Association of State Floodplain Managers, the Eastern Research Group, Minnesota Sea Grant, and the US Army Corps of Engineers, NOAA conducted an assessment of the economic benefits of green infrastructure in Duluth, MN. Through their research, project partners found that reducing the peak discharge by 20% for the watershed, 76 acre feet of storage would need to be stored under current rainfall and land use and 86 acre feet under projected future rainfall and land use. This storage could be reached through the use of green infrastructure like rain gardens, green and blue roofs, permeable pavers, tree plantings and native perenniels, extended detention wetlands, stormwater tree trenches and bio swales could not only significantly reduce peak flows but also save the city money in the long run . In total, green infrastructure could provide approximately $1.65 million in benefits to the community including but not limited to reduction of flood losses, increased recreation opportunities, and reductions in city infrastructure maintenance costs (NOAA, 2014).
After months of planning, the core project team convened a workshop in Duluth in the spring of 2014 to share the preliminary results of this assessment with political leaders, city staff including representatives from planning, engineering, parks and recreation, local researchers and state agency representatives stormwater utility representatives and other interested parties. Attendees were committed to identifying how the report's finding could be used to encourage the development of green infrastructure pilot projects and ultimately, how Duluth could use green infrastructure to meet its resilience goals (NOAA, 2014). This initiative is still on going with more meetings planned in the near future, together they hope to ensure that the community never has to feel the effects of another catastrophic flood.