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Flooding Mitigation

stormwaterThe City of Highland Park has a unique drainage system in that stormwater can either make its way through to two of the three “forks” of the North Branch of the Chicago River: the Middle Fork and the East Fork – better known as the Skokie River – are both located in Highland Park. The third drainage area for the City of Highland Park is Lake Michigan. Your residential location will determine your drainage location. The adjacent map depicts the City’s drainage areas. Each body of water is a regional asset since each flows through neighboring municipalities in addition to Highland Park. The Lake County Stormwater Management Commission (SMC) serves as the County’s central agency to facilitate regional stormwater management coordination.  The City of Highland Park operates and maintains storm sewer mains throughout the City.  There are separate drainage districts that are responsible for maintenance of the Skokie River (East Skokie Drainage District) and the Middle Fork (Union Drainage District).

A partnership between the City and its residents is necessary to advance the success of the community’s environmental goals. Homeowners are reminded that all projects must comply with City codes and ordinances, and to obtain necessary permits before construction begins. City values protecting residential and commercial buildings and structures from flooding as part of its goal of stormwater management.

It is important to distinguish between the different types of flooding events that can occur during rainfall events. These include:

  •  Flash flooding: Occurs after a short rainfall event that has a high level of intensity.
  • River flooding: Occurs when river basins overflow, possibly due to the combination of melting snow and spring rains.
  • Urban flooding: Occurs when natural surfaces are paved and lose their ability to absorb rainfall; the excess stormwater fills parking lots, yards and may flood basements.

Rainwater can enter basements through several means, such as leaks in the service line, or blockage in the service line, window wells blockage or cracks in basement floors or foundation walls. Poor lot drainage and plugged downspouts also contribute to seepage. In addition, flooding could be attributed to power failure, sump pump failure, a blocked connection between the home and the main sewer line in the street on service line or other related means.

Excess stormwater may also impact the sanitary sewer system that conveys wastewater from residential and commercial structures to the regional wastewater treatment plant, operated by the North Shore Water Reclamation District (NSWRD), on Clavey Road. This facility serves all of Highland Park, Highwood, Lake Forest, Lake Bluff, North Chicago, and portions of other communities north of Highland Park. The NSWRD receives wastewater via large “interceptor” sewer lines that accept wastewater from the collector sewer mains in the communities along its route. Because Highland Park is located at the “downstream end” where water flows, the City may experience flooding resulting from excess stormwater in the respective sanitary sewer systems.

Stormwater can enter into the sanitary sewer system in two ways: inflow and infiltration. Inflow is stormwater that enters the sanitary sewer system through points of direct connection to the system, such as downspouts or basement stairwells. Infiltration is when stormwater enters the sanitary sewer system through cracks or defects in sanitary sewer pipes. Wet weather can magnify inflow and infiltration sources. Once the sanitary sewer system reaches capacity, water may back up and potentially flood basements. As a result, inflow and infiltration can reduce a sanitary sewer’s ability to transport wastewater to the treatment facility.

Find helpful flood information on the Lake County Emergency Management Agency website. You may also enter a specific address into FEMA's "Flood Map" to see if your property is in a flood zone. To learn more visit FEMA's website.

Click here for a list of FAQs and additional information and tips on flooding prevention.