Heavy rain can cause urban flooding, and can happen far away from bodies of water. Flooding can happen when:

• The storm drain system is not big enough
• There are not enough storm drain inlets
• There is not enough green space to help stormwater naturally soak into the ground

Each situation can be different and can depend on a number of factors. Flood mitigation looks for the causes of flooding in specific areas, using modeling software to evaluate options that could reduce or eliminate the possibility of flooding.

In the past, flood mitigation projects have used these strategies to help prevent flooding:

• Adding new storm drain inlets and pipes so streets can drain faster
• Building stormwater holding ponds
• Building green infrastructure such as rain gardens

Computer modeling has been completed on approximately 90% of the city. These models can further identify flood areas and determine where our future flood mitigation efforts should be focused. We also receive flooding complaints that help to identify areas prone to flooding. All of these efforts have resulted in increased inspection and maintenance of these areas.

The Southwest Harriet area in Minneapolis has had a history of flooding challenges during large rainfall events. Computer models showed many structures, streets and parks could be subject to future flooding due to lack of capacity in the storm sewer system. A flood mitigation feasibility study was completed in 2018 to evaluate potential solutions. The City updated the flood study models for the Southwest Harriet area in 2022 to correct the existing pipe configuration and drainage patterns affecting one area of the model. The new models were also updated to use methodology that is more consistent with the way other flood areas have been modeled since 2018.