Chicago, Illinois Stormwater and Flooding Strategy - ON TO 2050

The Chicago Metropolitan Agency for Planning (CMAP) developed ON TO 2050 in 2018, a comprehensive region plan for the Chicago, Illinois region based on principles of inclusive and equitable growth; economic, environmental and climate resilience; and prioritized investments for infrastructure, development, and the economy. The Stormwater and Flooding Strategy is one component of ON TO 2050 that reviews the impacts of flooding, and explores policy recommendations and strategies to better prepare for and adapt to the impacts of urban and riverine flooding in the Chicago metropolitan region. CMAP offers adaptation strategies for stormwater and flooding that reduce risk to communities and critical infrastructure assets.

Northeastern Illinois experiences “significant and chronic damages from flooding,” and stormwater management and flood prevention can be particularly challenging due to the region's flat topography and broad floodplains. The report describes known existing damages from flooding locally, and how flooding impacts are projected to continue to rise due to climate change - with increasing intensity and frequency of storm events. The strategy paper presents many integrated approaches for the region to advance stormwater and floodplain management that include protecting and enhancing the stormwater services offered by natural areas and open spaces; avoiding investments in high risk areas such as floodplains; and minimizing stormwater runoff through development regulations and design standards.

The report presents CMAP’s strategies for managing stormwater and flooding in the Chicago region as related to the broader Recommended Actions to:

  • Identify and communicate flooding risk and exposure
  • Advance planning efforts to reduce current and future risk
  • Invest and maintain grey and green infrastructure
  • Increase resiliency of transportation system
  • Improve state and regional coordination

Table 3 lists these Implementation Strategies for each of the stormwater and flooding recommended actions:

CMAP found that parts of the region are more susceptible to flooding. These are largely locations that predate modern stormwater and floodplain management design standards and/or have been impacted by increased development within the watershed or sewershed. These higher risk areas also overlap often with Chicago’s most vulnerable communities.

One of the primary Implementation Strategies is to: Assess impacts to vulnerable populations, communities, and critical assets. CMAP recognizes that flooding has varying degrees of impact across communities, and that location, physical and socioeconomic characteristics, and capacity can significantly influence its degree of vulnerability to flooding.

CMAP recommends that County and municipal planners identify vulnerable populations at risk to flooding when conducting land use, transportation, hazard mitigation, and stormwater management plans and identify strategies to reduce flooding impacts.

CMAP has developed the Regional Urban Flooding Susceptibility Index (FSI) which uses past flooding damage claims to identify higher areas of relative flooding risk for both urban and riverine flooding. The Index was developed to help prioritize areas for planning and mitigation investment, particularly in locations with municipal capacity constraints that make it difficult to address these challenges. The report includes the methodology of the Index.

CMAP created two versions of the FSI to reflect the different causes and factors that contribute to urban and riverine flooding. The riverine FSI pertains to developed areas of the region within the Federal Emergency Management Agency (FEMA) 100-year floodplain or Metropolitan Water Reclamation District (MWRD) 100-year inundation layer within Cook County, and the urban FSI includes all developed areas of the region outside of those 100-year zones.


Publication Date: October 10, 2018

Author or Affiliated User:

Related Organizations:

  • Chicago Metropolitan Agency for Planning


Resource Category:

Resource Types:

  • Assessment
  • Policy analysis/recommendations

States Affected:


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