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Flooding Mitigation FAQs

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.

Frequently Asked Questions 

What is Stormwater Management?
Stormwater management is the method of channeling rainfall through pipes and sewers away from a property to an appropriate body of water or outfall. Excess stormwater requires careful management as the ramifications, like flooding, can negatively affect the City and residents. Typically, stormwater is managed through an underground storm sewer system. However, extreme rain events may overwhelm this type of municipal infrastructure. Excess water that travels on impervious surfaces (e.g. surfaces that do not absorb water), such as roads, may also become contaminated before reaching the outfall location.

Why Do We Flood?
With the ground already saturated to heavy rains, additional rainfall inundates the storm sewers and the two rivers, Skokie River and Middle Fork, overflows. It is simply too much rain in too short a time. The low lying areas, adjacent to the two rivers, including floodplain areas are at risk of flooding with the overtopping of banks and sewers surcharges.

What is the Short-Term Solution to Mitigate Flooding on my Property?
Unfortunately, the risk of flooding cannot be completely prevented, especially for those living in the floodplain areas, but there are certain things that can be done to your property to help mitigate the flooding and help alleviate some damage.

  • Inspect flood protection devices such as backflow preventers, sump pumps, and battery backups, check valves, standpipes, etc., to be in good working condition.
  • Storm (rainwater) and sanitary (wastewater) lateral service pipes (running from home to street) should be free of roots and debris. Have these lateral services inspected and cleaned by authorized licensed plumbers.
  • Storm lateral service pipe should not be connected to sanitary lateral service pipe or vice-versa. These two lateral pipes should remain separate and be connected separately to City storm and sanitary main pipes. Contact an authorized licensed plumber for inspection and verification. If a cross connection exists, obtain a building permit for corrected work.
  • All exterior drains, such as window well drains, outside yard drains, gutters, street drains, etc., should be clear of debris, leaves, and other obstructions.
  • Install an overhead sanitary system to alleviate sewer backups. 

Does the City Have Programs to Assist Residents with Flooding?
Rain gardens, Rainbarrels and Retrofitting
The City has investigated and implemented alternative methods to assist with stormwater management. The rain garden is designed to temporarily detain stormwater during heavy or prolonged rain events in order to reduce the rate of surface runoff. In 2017, the City initiated a rain barrel program to help residents obtain low-cost rain barrels. These alternatives are gaining acceptance as measures that can aid in onsite stormwater management. To learn more about residential stormwater management techniques that may have aesthetic and functional benefits, please see the following brochure, Discovering the Benefits of OnSite Stormwater Management.

The City has worked with Northwestern University to develop a Green Infrastructure Summary sheet assisting residents with sustainable alternative programs to assist with urban flooding. A copy of the summary sheet is available here

Another option residents may consider to mitigate potential flooding is retrofitting. Retrofitting involves initiating changes to an existing property in order to protect it from future hazards. Homeowners can make various types of structural changes to existing property by implementing improved construction technology. To determine if retrofitting is a viable solution, view FEMA's Homeowner’s Guide to Retrofitting.

Voluntary Sewer Lateral Cost Share Program
The purpose of the Voluntary Sewer Lateral Cost-Sharing Program is to assist homeowners in minimizing house and property flooding due to sanitary sewer surcharges by addressing the condition of the private sewer lateral, through full lining or complete replacement, or overhead plumbing or other approved sewer backflow-preventing devices.  If approved for the Program, residents would be eligible for up to 20% or a maximum of $1,260 reimbursement, whichever is less of the total cost of the private sewer lateral rehabilitation. Learn more.

What is the City Currently Doing to Address Flooding?
The City of Highland Park has been working with both Lake and Cook Counties, Illinois Department of Natural Resources and the US Army Corps of Engineers (ACOE) on a long-term flood mitigation solution following several floods that devastated parts of Highland Park and dozens of communities throughout the region. The mitigation solution would be effective for the residents of Highland Park and other area residents who live along the Skokie and Middle Fork Rivers. A comprehensive regional study is necessary to identify opportunities to mitigate flooding occurring in the community. 

The Highland Park City Council approved an agreement with ACOE for a preliminary study related to regional flood mitigation solutions. 

The Skokie River, East Fork of North Branch Chicago River, is under the jurisdiction of US Army Corps of Engineers (ACOE) and flows through Lake and Cook Counties.  Highland Park is at the downstream end of Skokie River within Lake County and the river eventually flows into Skokie Lagoons. Part of the preliminary study, to be undertaken by ACOE, is to determine if a feasibility study is required that will entail flood protection solution for all communities along this river. If a final feasibility study is undertaken, the potential solutions could result in a combination of storage basins, retaining walls, pump stations, buy-outs, and other measures. Any structural solution, if implemented in the long-run, should not adversely impact both downstream and upstream properties. At this juncture, ACOE is scheduled to begin the preliminary study in September 2018. The preliminary study will take approximately nine months to complete. 

Storm and Sanitary Sewer Master Plan
The City of Highland Park, in conjunction with various third-party engineering consultants, has developed master plans for both the City’s storm and sanitary sewer systems that identify future capital projects that are scheduled for completion. The purpose of these master plans is to develop a comprehensive approach to operating, maintaining and improving the City’s storm and sanitary sewer systems. 

Since the mid-1990s, the City has completed improvements to over 27 miles of its storm and sanitary sewer lines. The City’s long-term neighborhood infrastructure improvement program has identified seven priority areas requiring a significant reduction of inflow and infiltration into the City’s sanitary sewer system. City storm sewers are designed and constructed for a 10-yr storm. A 10-yr rain event is classified as a storm possessing an intensity that has a 10% chance of occurring in any given year.

In addition, City has lined City-owned and maintained sanitary sewer mains to extend their life cycle and functionality. And to prevent stormwater infiltration on sanitary sewers.  

Has the City Considered Dredging the Skokie River?
Dredging is a major undertaking that must be initiated by the ACOE. The Skokie River has multiple jurisdictions such as ACOE and Drainage Districts along with all municipalities through which the river flows. The Skokie River begins up north (around Washington St in Waukegan) and ultimately discharges into Wilmette Golf Course where it merges with Middle Fork of North Branch Chicago River. The ACOE-initiated projects typically take multiple years to plan and study. The construction phase takes anywhere from 7-10 years after initiation of a study. ACOE is reviewing all long-term flood solutions including potential dredging. 

Has the City Considered a Buy-Out Program? 
The City has explored the FEMA Buy-Out program, administered by Lake County. The program is strictly a volunteer program. Lake County seeks grant funding from FEMA on these buy out programs, and, if successful, 75% of the cost is paid by FEMA and 25% is paid by the municipality.

If a home qualifies (there are very specific criteria to meet), then Lake County will work with the City and FEMA to administer the buyout. City Council has committed to supporting the Buy Out program for qualifying homes. Each year, Lake County will accept applications from homeowners interested in participating in the program. The timeline, if successful in receiving FEMA funds, could range between 2 to 3 years from the initial submission of an application.

Are There Other Programs Available for Homeowners who Experience Flooding?
The City belongs to the National Flood Insurance Program (NFIP) that requires the City to apply and enforce floodplain regulations in compliance with FEMA, IDNR, and Lake County Watershed Development requirements. FEMA under the Increased Cost of Compliance (ICC) coverage provides up to $30,000 to help cover the cost of mitigation measures that will reduce flood risk. To qualify for ICC coverage, a building has to be substantially damaged or meet the criteria of a repetitive loss structure. For additional details, please review the ICC coverage Fact Sheet

Is There a Valve that Can Be Opened in the Chicago Botanic Garden?
There is no valve to be opened.

In the 1960’s, the Chicago Botanic Garden constructed a structure called a weir (resembling a wall) on the Skokie River just downstream of the Lake Cook Road Bridge (in Cook County). The weir was intended to keep the low flows of the Skokie River, and associated pollutants, out of the ponds in the garden. A “diversion channel” was also constructed at this time to maintain/direct the low flows of the Skokie River around the garden; avoiding the ponds. When the Skokie River rises to the top elevation of the weir, it overflows into the garden. Once the river reaches the top of the weir, no valves or locks are necessary. The river flows into the garden unrestricted. The flow in the diversion channel continues unrestricted.  There is nothing at the garden that can be “opened” to lower the level of the river. The Skokie River will begin receding as the rain stops and the flow from “upstream” passes through Highland Park.

What is a Floodplain?
A portion of Highland Park, the low-lying areas adjacent to the two rivers, falls into the floodplain. Properties within the floodplain are susceptible to flooding. The flooding greatly impacts residential properties located near the Skokie River and the Middle Fork as water flows from north (Old Elm Road) to the south (Lake Cook Road) within Highland Park. The Skokie River discharges into the Chicago Botanic Garden, whereas the Middle Fork drains into the Northbrook Court pond. Both these rivers ultimately merge and flow through Cook County Forest Preserve property, west of Wilmette Golf Course. By their very definition, these areas are governed by Federal, State, and local regulations. The City adopted two floodplain regulations, one is the FEMA floodplain that is required to provide subsidized flood insurance and the City’s floodplain. The City floodplain area is a higher threshold than FEMA’s to protect the homes.  The floodplain map can also be viewed on the City’s website under Interactive Maps (click "Layer" on the top right, select your community, and then select the floodplain layers you wish to view).

Highland Park Flood Plains 
A copy of FEMA floodplain areas are seen in Highland Park Flood Plain Map.  The City of Highland Park (CHP) floodplain zone provides added security (higher flood protection elevation) than FEMA floodplain area. Please see map above showing the limits of City of Highland Park floodplain area (light blue color) and City’s storm sewer system (red color). You can view any property within FEMA floodplain areas by going to FEMA Map Service Center.

 The Illinois Residential Real Property Disclosure Act
The Illinois Residential Real Property Disclosure Act requires that all home sellers disclose whether or not the home for sale is in a floodplain. Residents who are unsure if their property is in a floodplain can visit the FEMA website.

Most of the street flooding occurs in low lying areas and most of the homes impacted are the ones built before the adoption of CHP or FEMA floodplain maps and stormwater management ordinances. All new developments (commercial or subdivisions) are to comply with Lake County watershed development ordinance whereby detention and floodplain compensatory storage is required to be stored on property equaling 100-year event in a 24-hour rainfall.  As the Skokie River rises, the outfall of City storm sewer system is surcharged thereby causing water to back up into the pipes and ultimately releasing out of inlets on streets. The creek overtopping occurs when too much rain falls in short duration or too much persistent rain falls over a long time. 

Has the Flooding on My Property Has Worsened?
The reason properties are experiencing increased flooding is because the area has experienced frequent events of record-breaking rainfall in a shorter amount of time. Flash floods in 2017 broke records for the wettest days in recent history. Over 4 inches of rain fell nonstop, on an already saturated ground, resulting in flooding throughout the area. 

What Should I Do If I Am Experiencing Flooding?
Residents experiencing flooding should:

  • Use reasonable precautions to protect your family from contaminated or flooded waters;
  • Restrict use of plumbing appliances until rains subside including dishwasher, showers, toilets, laundry and other appliances;
  • Identify the source of flooding and call an appropriate licensed professional;
  • If you are experiencing a sanitary sewer backup, in addition to calling a licensed plumber please also contact Public Works Department at 847.432.0807 (during business hours) or 847.432.7730 (after-hours).

Sandbags are available to be filled at the City Of Highland Park Public Works Facility, 1150 Half Day Rd.  

Are There Health Risks Related to Floodwater Contact?
The Lake County Health Department has provided important health and safety information to protect individuals in the event of a flood. Read their comprehensive tips about how to stay safe when and after flooding has occurred.

How Do I Dispose of Items Damaged by the Flood?
If you have items that need to be removed due to flood damage, please call Lakeshore Recycling at 773.685.8811 for pricing and to schedule a pickup.

How Do I Find Street Closure Information?
For updated road conditions, please visit Lake County PASSAGE at

Where Can I Report and Find Out What Streets are Flooded in a Storm?
Flooded streets can be reported 24/7 by using the City’s Non-Emergency Request Tracker on the City website. This feature can be used to report flooding and view streets that have already been reported.   This link can also be used to report other service requests to the City.

Residents can also report street flooding by calling Public Works at 847.432.0807 during business hours or calling police non-emergency after-hours at 847.432.7730.

Where Do I Sign-up for City Communication Regarding Flooding? 
eNews & Social Media
The City issues communication alerts via eNews, the website, and social media.   When the City receives an alert from the Lake County Emergency Management Agency, the alert is then sent out through the City’s Public Safety Alerts eNews, posted on the City website, and posted on our social media pages (Facebook and Twitter). Residents are encouraged to sign up for the City eNews and Public Safety Alerts eNews at

 Emergency Notification System
The City of Highland Park has an Emergency Voice Notification System, a high-speed telephone communication service for emergency notifications. The system allows the City to telephone the entire community or a targeted area in the event of an emergency that requires immediate action. The system is only used in emergency situations such as a boil order notification, missing persons, evacuation notices, gas leaks or other emergencies where rapid notification is essential for public safety. Published residential and business telephone numbers are automatically downloaded into the system. Residents with unlisted numbers or cell phones should register to ensure they receive notification. Sign up at

Storm Recovery Contact Information

 City Public Works Dept.  847.432.0807 
 City After-Hours 847.432.7730
 ComEd       800.334.7661
 North Shore Gas    866.556.6004
 Lake County Health Dept. 847.377.8000
 AT&T Landline Service   800.288.2020
 Lakeshore Recycling Systems     773.685.8811
 Emergency Assistance   911

Find helpful flood information on the Lake County Emergency Management Agency website.