Abstract

A record-breaking 24-h rainstorm on 17–18 July 1996 was centered on south Chicago and its southern and western suburbs, areas with a population of 3.4 million. The resulting flash flooding in Chicago and 21 suburbs broke all-time records in the region and brought the Illinois and Mississippi Rivers above flood stage. More than 4300 persons were evacuated from the flooded zones and 35 000 homes experienced flood damage. Six persons were killed and the total estimated cost of the flood (losses and recovery actions) was $645 million, ranking as Illinois’ second most costly weather disaster on record after the 1993 flood. Extensive damages and travel delays occurred on metropolitan transportation systems (highways and railroads). Commuters were unable to reach Chicago for up to three days and more than 300 freight trains were delayed or rerouted. Communities dealt with removal of flood-damaged materials, as well as damage to streets, bridges, and sewage treatment and water treatment plants. Reduced crop yields in adjacent rural areas represented a $67 million loss of farm income. Conflicts between communities developed over blame for the flooding due to inadequate storage capacity resulting in new regional flood planning. Federal and state aid ultimately reached $265 million, 41% of the storm costs. More than 85 000 individuals received assistance, and 222 structures have been relocated under the federal Hazard Mitigation Grant Program at a cost of $19.6 million.

Introduction

Record-setting rainfall during 24 hours on 17–18 July 1996 produced a wide variety of physical and socioeconomic impacts. The major direct physical effect was the excessive flooding along four rivers and their tributaries in northeastern Illinois. High rainfall rates and flood waters eroded soils and damaged existing structures such as bridge abutments and roadways. Damaging flooding was recorded in south Chicago, in a sizable suburban area west and south of the city, and in several small rural communities across northern Illinois. Flood damages were maximized because this record-setting event occurred across a densely settled metropolitan area.

Other forms of severe weather also included four tornadoes, excessive cloud-to-ground lightning, large hail in numerous locales, and damaging surface winds throughout the heavy rain area. Lightning and the ensuing flooding caused six deaths. Hundreds of thousands of people endured severe emotional stress related to flood damage, delays in transportation, evacuation from residences, life in temporary residences, and their efforts to rebuild their lives after the event. Storm losses were estimated to be$645 million, making this weather disaster in Illinois second (in damages) only to the flood of 1993.

There are several limitations in the compilation of the costs of impacts, responses, and recovery to a flood event. Costs of a sizable event such as the July 1996 flood cannot be measured with a high degree of accuracy for several reasons. Some costs simply are not available. A highly detailed analysis of costs from an event of this magnitude would require intensive studies by several investigators lasting over two or three years after the event to capture all costs related to delayed recovery activities. Hence, the reported values herein relating to losses due to impacts (damages) and costs of responses and recovery activities made a year after the 1996 flood are best estimates based on reports from several individuals and institutions; thus, they are only approximations of the real costs.

This assessment of storm impacts, responses, and recovery actions was based on available urban and regional loss data, accounts in local newspapers, and on information provided by state and federal emergency management agencies. The text is arranged in chronological order beginning with impacts of the storm and floods, the immediate responses to actual and threatened damages, and the recovery actions, some of which persisted more than a year after the event.

Part I: Impacts

Flooding and erosion

Magnitude of river flows

A record short-duration rainfall typically produces record, or near-record, streamflows on rivers and streams affected by the heaviest rains, and such was the case in this storm. All basins shown in Fig. 1 had flows much above flood stage. Fortunately, prior to the rainstorm, the levels of flow in these basins were relatively low.

Fig. 1.

The total storm rainfall for 17–18 July 1996 and major river basins in the storm area. Many of the rivers and tributary streams in these basins experienced flooding as a result of the storm including the Kishwaukee, Fox, Sable, Des Plaines, DuPage, and Kankakee Rivers.

Fig. 1.

The total storm rainfall for 17–18 July 1996 and major river basins in the storm area. Many of the rivers and tributary streams in these basins experienced flooding as a result of the storm including the Kishwaukee, Fox, Sable, Des Plaines, DuPage, and Kankakee Rivers.

Just three hours after the rains had ended (1600 LST 18 July), record flow peaks had already occurred at 14 stream gauges. At 2200 LST 18 July, the flow in the Des Plaines River near Joliet was a record 940 cm3 s−1 with a mean velocity of 1.8 m s−1. By 19 July, the flows of all flooded rivers were at record highs, with velocities of 3–4.3 m s−1.

Figure 2 shows the stage hydrographs for two small streams in the flooded region and their rapid response to the heavy rains. Water levels rose 3 m or more in just a few hours and created flash floods.

Fig. 2.

Stage hydrographs for river flows on (a) the south branch of the Kishwaukee River at DeKalb, (b) Blackberry Creek near Yorkville, and (c) the south branch of the Kishwaukee River near Fairdale. These show the sudden increases in flows during the storm and just after the heavy rains ended. Data provided by the U.S. Geological Survey.

Fig. 2.

Stage hydrographs for river flows on (a) the south branch of the Kishwaukee River at DeKalb, (b) Blackberry Creek near Yorkville, and (c) the south branch of the Kishwaukee River near Fairdale. These show the sudden increases in flows during the storm and just after the heavy rains ended. Data provided by the U.S. Geological Survey.

Table 1 presents the peak stages of rivers that exceeded their flood stage and the dates of the peak value. Peaks on the Fox, Des Plaines, DuPage, and Kishwaukee Rivers set new records (their locations appear in Fig. 1). All peaks occurred between one and four days after the rainstorm, with the delay dependent upon basin size and the time to accumulate the floodwaters. A smaller basin, the Des Plaines River at Riverside (1640 km2) peaked on 18 July, whereas a larger basin, the Kankakee River at Wilmington (13 390 km2), peaked on 22 July, four days after the rains ended. Accumulated flood flows caused the Illinois River at Marseilles to exceed flood stage, and heavy rains in northern Illinois brought the Mississippi River above flood stage at Keokuk, Iowa, by 22 July.

Table 1.

Selected rivers that exceeded flood stages after the 17–18 July 1996 rainstorm.

Selected rivers that exceeded flood stages after the 17–18 July 1996 rainstorm.
Selected rivers that exceeded flood stages after the 17–18 July 1996 rainstorm.

Excessive runoff also brought the monthly river flows for July 1996 to levels much higher than normal. Table 2 shows the July 1996 mean flows and the long-term averages at selected rivers. July 1996 flows of the Rock, Fox, and Kankakee Rivers had chances of exceedance of 4% or less.

Table 2.

July 1996 streamflows for flooded rivers.

July 1996 streamflows for flooded rivers.
July 1996 streamflows for flooded rivers.

Residential flooding

Excessive overland flows and the record river flows created excessive residential flooding in 21 communities plus Chicago, areas with a population of 3.4 million. Extensive residential and commercial development during the past 40 years had occurred in the areas with the heaviest rainfall. Considerable suburban flooding occurred well beyond floodplains in areas where detention ponds had filled and excess water flow occurred overland in gulleys, ditches, and streets. Table 3 provides examples of the types of flooding that occurred. The Federal Emergency Management Agency (FEMA) estimated that more than 35 000 residences were flooded by the 17–18 July rainstorm (Changnon 1996a).

Table 3.

Examples of the types of residential flooding during July 1996.

Examples of the types of residential flooding during July 1996.
Examples of the types of residential flooding during July 1996.

Business/industry flooding

Several businesses and industries along the Fox and Des Plaines Rivers experienced damaging flooding. For example, a nursery incurred losses of $1.5 million after floodwaters swept away all of its plants and trees. In Aurora, where a record 43 cm rain fell, half of the commercial establishments experienced flood damage.

Businesses selling water pumps sold out at all area stores. Although construction firms could not build homes in the region for four to six weeks after the July rainstorm, they later achieved increased business from the extensive repairs to the many flooded homes (Changnon 1996a).

Flooding of highways and streets

Country roads, city streets, state and federal highways, and interstates were flooded, leaving many damaged. This flooding brought major delays in human and freight movement through the region, particularly on 17–19 July, and damages to streets and highways. Floodwaters submerged more than 1200 vehicles because the flooded area encompassed numerous, extremely busy transportation arteries that center on Chicago, including four interstates that were closed for one to three days, trapping many vehicles and forming what was labeled as “Illinois’ largest parking lot” (Changnon 1996a). Flooding of major highways also closed off access to six suburban communities for one to two days.

Widespread damages to streets and highways occurred because of the erosive powers of the floodwaters. The force of the flash floodwaters also eroded the fill around the abutments of many bridges, causing the collapse of eight bridges. Another result of the flooding, particularly during the rainstorm, was a 280% increase in automobile accidents. Two persons died when their vehicles were swept away and inundated by floodwaters.

Flooding of railroads

Four railyards were flooded and five railroads experienced major flooding and damages. Canceled or rerouted trains and delayed travel had serious repercussions since Chicago is the nation’s rail hub with vast amounts of freight exchanged among the 13 railroads entering the city.

Flooding and blockage of the rail lines stopped Amtrak service and halted Chicago’s extensive METRA commuter service west and southwest to the suburbs for one to three days. On 18–19 July, 46 000 commuters could not use METRA service to reach their workplaces. Amtrak also stopped 14 trains operating daily through the flooded area (Changnon 1996a).

Damages to the railroads included erosion of road beds, erosion and damage to bridges, and mudslides. Six bridges had to be replaced, and 19 miles of track were washed out. The railroads responded by moving several special trains of ballast (rock) from the western and southwestern United States to rebuild their lines, and most main lines reopened on 19 July. Considerable water damage to signal systems also stopped train movements. The railroads had to reroute 368 trains at a cost of $12 million, and in total railroads incurred losses of$48 million due to direct damages, train delays, and train reroutings.

Impacts on city governments

Many city governments were severely impacted as 21 communities experienced severe flooding of residences and 9 of these communities experienced extensive flooding of businesses. These problems included damaged streets and bridges; removal of flood-damaged materials; and the flooding of city-operated facilities, including sewage treatment and water treatment plants. For example, one county spent $1.3 million to repair damaged roads and bridges, while another town spent $1.8 million to repair damaged streets and city structures. Most urban expenditures related to response and recovery actions.

Agricultural impacts

Heavy rainfall rates and rapidly moving floodwaters produced two major impacts on regional agriculture. First, the high waters flooded croplands, particularly those poorly drained or in and near river valleys, causing serious yield reductions or total crop losses. Second, the force of the high rain rates and swift floodwaters caused a considerable amount of soil erosion on uplands and river lowlands. Research has shown that extensive erosion occurs with heavy rainfall (Bhowmik et al. 1980), and the excessive rainfall rates on 17–18 July, particularly during the nocturnal storm, created sizable amounts of soil erosion. Numerous dairy farms in the rural areas west of the Chicago metropolitan area suffered flood damage to their facilities and losses of stored feed.

Yields of corn and soybeans in 1996 from the 13 600 km2 area that experienced rains greater than 15 cm during the storm were compared with those of eight adjacent counties with rains less than 5 cm. Corn yields were examined for regional differences in 1996 and in 1995. The 10-county area with heavy rains had an average yield change of +15 bushels per acre in corn from 1995 to 1996, whereas the eight adjacent counties experienced an increase +22 bushels per acre (Changnon 1996a). Thus, the counties without the heavy July rains had yield increases that were nearly 50% (22 bushels versus 15 bushels) greater than in the flooded counties. The corn loss of 7 bushels per acre represented a farm income loss of $23 million.

Soybean yields in the 10 counties with heavy rains averaged 32.5 bushels per acre, whereas yields in the eight adjacent counties without heavy rains averaged 42 bushels per acre (Changnon 1996a). The lower yield, a reduction of 23%, represents an income loss of $44.5 million, bringing total crop losses to farmers of $67.5 million. This does not count other losses suffered by grain handling and storage companies.

Societal impacts

Widespread concern quickly developed over the effect of the heavy rains and ensuing flooding on the health and welfare of the 3.4 million Illinois citizens living in the area. Six persons died as a result of the storm: three drowned (one in a flooded basement); two died from heart attacks while working during the flood;and one person was electrocuted by lightning (Changnon 1996a). Health concerns resulted in free tetanus shots provided by the Red Cross. There was also considerable concern over possible encephalitis outbreaks due to feared massive development of mosquitoes in the flood areas, but this did not occur.

High stress among more than 35 000 flood-stricken families was a major impact and the flood forever altered the lives of many flood victims. Life savings were often used to pay for damages, and many mothers reportedly went back to work to help recoup family finances. With as many as 4000 persons evacuated, there was enormous stress due to loss of homes and personal possessions, as well as being displaced in various types of housing. Floodwaters brought snakes into several homes, giving rise to fears of snake bites. Social workers predicted an increase in the “homeless” among people who were barely scraping by before the flood and then made homeless by flood damages. Flood workers, including police and fire departments, worked overtime and were also under great stress from the excessive hours.

Conflicts also resulted, producing further stress. For example, two engineers working for Orland Park were arrested for pumping water out of Orland Park into Tinley Park. Residents in Aurora and Joliet claimed their cities were giving greater help in affluent neighborhoods than in less affluent neighborhoods, producing conflict between residents and city managers. In addition, the flooded residents of flooded areas blamed upstream suburban developments for their plight.

Severe storm damages

The sequence of thunderstorms that produced the excessive rainfall on 17–18 July also produced high winds, hail, and frequent lightning. Lightning caused widespread power outages that affected 23 000 service units in the area (Changnon 1996a). Lightning-set fires burned several homes. Winds in excess of 96 km h−1 in several urban locations extensively damaged trees and structures. Winds also caused trees to block some railroads and highways in and near the Chicago area. Hail damaged crops in DeKalb and Ogle Counties, producing 50% crop losses across 23 km2.

Water quality effects

Excessive rains and flooding produced several problems affecting water quality. Faced with flooded basements and excessive water in the Chicago River system, the Metropolitan Water Reclamation District of Chicago had to release polluted water into Lake Michigan to ease the urban flooding. This action led to Chicago beach closures for several days after the storm (Changnon 1996a).

Many sewage treatment plants were unable to handle the rush of floodwaters and diverted raw sewage into local streams and rivers. At Sugar Grove, the flood damage caused the sewage treatment plant to be out of commission for eight weeks and repairs cost $250 000. Sewage treatment plants in DeKalb and Plainfield were also seriously damaged, representing a repair cost of$350 000 at Plainfield (Changnon 1996a). Damaged water treatment plants in some rural communities were out of commission for a few days, causing a loss of drinking water to an estimated 8000 residents.

Beneficiaries

Every weather disaster provides a certain number of “winners” who benefit from the event (Changnon 1996b), and the July 1996 storm was no exception. Businesses selling water pumps made record sales. Materials from flooded buildings and residences had to be hauled away, a boon for waste haulers. For example, 75 000 tons of water-damaged material in Aurora were hauled to landfills in three days, with a total of more than 100 000 tons removed by 24 July (Changnon 1996a). Homebuilders and construction firms also reaped benefits in the aftermath of the flood due to the rebuilding of businesses and residences. The widespread rains on 17–18 July also affected the Chicago Board of Trade: corn futures fell 10%, from $3.82 on 12 July to $3.45 on 19 July (Changnon 1996a). Some investors won and others lost from this action.

Part II: Responses

The July rainstorm and ensuing flooding produced immediate responses ranging from the simple act of walking out the door of a flooded home to declaring most of northeastern Illinois a disaster area. There is some overlap between “impacts,” “responses,” and “recovery acts” associated with disasters. An impact is the physical damage and disruption; a response is an action taken quickly to adjust to an impact; and recovery involves actions taken weeks, months, and years after the event to ameliorate the impacts.

Responses to the flooding problems were classified into two general areas: actions of individuals and actions of government agencies. Damaged private sector firms such as the local railroads also responded to make repairs to their facilities.

The principal response during the storm and three days thereafter was the evacuation of individuals from flooded homes and communities. The number of persons who left their homes by boat, helicopter, or other means was extensive: 900 in Aurora, 800 in Orland Park, several hundred in Kirkland, 700 from a subdivision near Lisle, and 1200 in Grundy County communities. In addition, several other towns reported evacuations ranging from 50 to 300 persons. Altogether, it is estimated that more than 4000 people had to be evacuated from flooded residences and businesses (Changnon 1996a).

Evacuations were handled by local police, fire departments, and state police. Governor Edgar sent three national guard units to assist with evacuations, traffic direction, and other forms of assistance. Immediately after the storm, the Red Cross and the Salvation Army established shelters for the evacuees, provided food, and clothing. Many of the evacuees were allowed to return to their homes by 22 July.

The other major area of immediate responses concerned actions of government bodies. On 18 July, Governor Edgar declared 15 counties in northeastern Illinois as State Disaster Areas (Changnon 1996a). The Gubernatorial Proclamation is a requirement prior to requesting federal assistance. The initial state estimate was $24 million for low-interest loans. As a result of the governor’s letter requesting assistance for 11 of the 15 counties, President Clinton designated these as major disaster areas on 25 July. Federal programs that provide assistance to individuals, businesses, and jurisdictions (village, cities, and counties) or other public entities include personal and business (low-interest) loans, rental assistance, temporary housing, and up to 26 weeks of unemployment pay.

FEMA, working in concert with the Illinois Emergency Management Agency (IEMA) and the Small Business Administration (SBA), formed 16 teams to perform preliminary damage assessments to determine whether federal assistance was required. These groups began going house to house on 22 July to assess damages and check flood insurance coverage. Ironically, results showed that only 1% of those with flood damage had flood insurance, continuing a trend far worse than that found in the 1993 Midwestern flood (Changnon 1996b).

A major activity of city governments in severely flooded locations involved the removal of damaged materials such as ruined household goods and damaged house materials from the flood zones. For example, 75 000 tons of material, the equivalent of more than two months of garbage, were hauled to Aurora landfills during three days following the flood. Seventy-five trucks were used for several days to haul away flood-damaged materials in Naperville, and the city of Chicago loaned 50 garbage trucks to Plainfield to help that city dispose of flood debris.

The mayor of Aurora, the city with the greatest amount of flood damage, declared a city-wide emergency at 0200 LST on 18 July, and directed fire trucks and the police to help evacuate people from flooded areas while the intense rains were still in progress. Many volunteer actions also occurred. For example, students at Northern Illinois University helped fill sandbags to protect their school from the flood in DeKalb. DuPage County’s Trauma and Disaster Team went to work on 19 July, providing information, giving tetanus shots, and counseling flood victims.

Part III: Recovery activities

Recovery activities continued for weeks, months, and years after the flood. The Salvation Army kept several mobile units in the flood areas to feed flood victims for three months. Several communities used local schools, unoccupied in the summer, for temporary shelters lasting into August. The Red Cross organized and set up emergency shelters and provided food in Rockford, DeKalb, and Frankfort for six weeks. Furthermore, several food stores and area food chains provided free food to shelters for many weeks.

Another continuing activity for up to four weeks after the flood was the removal of flood-damaged materials. By 24 July, debris removal in Aurora had amounted to more than 100 000 tons. Aurora added 100 trucks to haul waste, and it took three weeks to get all the ruined materials to local landfills.

Along with the losses and misery, the flood produced a variety of interesting conflicts. Frequently, the victims of the flood and local municipal leaders became deeply concerned about the causes of the flooding, concerns that were expressed for many weeks after the flood. Cities blamed other cities, regional authorities, and state agencies for many of their ills. In many cases, upstream communities were thought to be at fault. Claims of inadequate water storage facilities, such as detention basins, in various communities were often stated. The flood’s magnitude, well in excess of 100-yr design levels [see Angel (1999)], exceeded the design criteria for urban and suburban detention facilities. When this information became widespread, most debates ended and many called for regional flood planning. However, there was no central regional authority to deal with flood control and developments affecting flooding. The U.S. Army Corps of Engineers identified the need for flood planning in Chicago and requested additional funds for such planning (Changnon 1996a).

Another major long-term recovery action relates to government activities in two broad categories: 1) aid and assistance by federal, state, and local agencies and 2) changing rules, regulations, and laws, largely at the local scale, in response to the flooding.

Aid and assistance by government agencies

Shortly after the flood, IEMA estimated federal flood relief funding needs as follows: $72.8 million in SBA loans, $32.9 million for housing aid and individual grants, and $28.1 million for public assistance to local governmental entities. Thus, the initial scope of funding seen as needed from the federal government amounted to $133.8 million. Ultimately, the federal total relief funds for these programs grew to $241 million, more than $100 million above the early estimate. This reflects a commonly observed problem with floods in that early damage estimates are typically much too low (Changnon 1996b).

FEMA established a Disaster Field Office in the region, and an estimated 200 staff members were assigned there full-time from late July 1996 until it closed in late October. Assistance provided through FEMA, as a result of the president’s declaration for major disaster status in 11 counties, included three federal programs:

  1. Individual Assistance (IA) Program, including SBA low-interest disaster loans and the Individual and Family Grant Program;

  2. Public Assistance (PA) Program for state and local governments and certain private, nonprofit organizations to cover debris removal, protective measures, and repairs to facilities; and

  3. Hazard Mitigation Grant Program (HMGP) for state and local jurisdictions that sponsor a mitigation project that will eliminate or lessen the impact should the hazard/disaster reoccur.

All 11 counties were eligible for the Individual Assistance and Hazard Mitigation Programs, and all counties except Winnebago were eligible for the Public Assistance Program, which provides 75% of the funds for eligible projects. Actions pursued under these three federal programs are now described.

  1. Individual Assistance Program. For all types of assistance, individuals were directed to contact FEMA in person or by telephone. FEMA established 10 recovery centers throughout the region by 27 July. There, individuals could receive counseling and guidance about the various aid programs. More than 10 000 persons visited the centers during the first month after the flood, and more than 72 000 applications for funding assistance were ultimately received. Cook County had more than 52 482 applications, which represented 70% of the total received. Other counties with many applications included DeKalb (1500), Du Page (2900), Kane (7500), and Will (5890). Each of the remaining six counties had less than 1000 applicants.

    Table 4 shows the applications taken in three major IA programs, the eventual eligible numbers, and the dollar amounts of the grants disbursed as of 30 September 1996. Individuals who qualified for SBA loans were ineligible for the Individual and Family Grant (IFG) Program; however, many individuals received temporary housing assistance in addition to SBA and IFG. Data in Table 4 reveal that the greatest number of applicants, both applying and eligible, applied for the Temporary Housing Program (more than $128 million disbursed), followed closely by SBA loans ($95 million). The total federal funding dispersed under these three programs was $226.8 million.

  2. Public Assistance Program. Government payments included grants to local and state government entities to cover 75% of the costs of debris removal; emergency measures taken during the flood; and permanent repair of facilities such as roads, bridges, and public facilities. Since PA is a matching program, IEMA administered the federal reimbursement of the 75%, and the local entity was responsible for providing the other 25% in funds. Federal funding to Cook County was $3.0 million, Will County got$2.9 million, and Kane County got $2.5 million, reflecting the suburban communities that were most severely impacted by the flood. In addition to receiving the 75% grant, the public entity received administrative costs on the total project. There were 267 applicants for PA funds and they received a total of $13.8 million in federal funds and provided $4.6 million themselves.

  3. Hazard Mitigation Grant Program (HMGP). The federal government has recognized the importance of hazard mitigation, defined as taking action to reduce or permanently eliminate the long-term risk from natural hazards. HMGP involves the acquisition of homes, mobile homes, businesses, churches, and vacant lots from the floodplains, and turning private property into public ownership. The program’s aim is to end the cycle of “damage–repair and damage again.” HMGP is a voluntary program on the part of the property owner and consists of 75% federal funding and 25% nonfederal (local) funding. Jurisdictions must apply on behalf of their affected residents who have experienced repetitive flooding. HMGP was administered by IEMA for the July 1996 flood, and all flooded jurisdictions were invited to apply for participation in the HMGP acquisition program. Five counties and 19 communities responded with potential projects totaling $48 million of which$14 million was for structural projects. After review, the structural projects were denied, and 14 other applicants were invited to submit formal applications for their proposed projects. The HMGP flood expenditures totaled $19.6 million, and Table 5 shows the projects with structures and properties relocated and related expenditures.

Table 4.

Number of applications for aid under three federal programs as of April 1997.

Number of applications for aid under three federal programs as of April 1997.
Number of applications for aid under three federal programs as of April 1997.
Table 5.

Projects and related expenditures under the Hazard Mitigation Grant Program.

Projects and related expenditures under the Hazard Mitigation Grant Program.
Projects and related expenditures under the Hazard Mitigation Grant Program.

Changes in rules, regulations, and laws

Certain communities in the severely flooded areas made interesting changes in rules and regulations. For example, Aurora, Naperville, and Montgomery chose to temporarily waive future permits and fees for the repair and rebuilding of flood-damaged homes. DuPage County also joined in the waiving of construction permits. Aurora decided on 22 August to limit future development of the city in certain areas, required that the Burlington Northern Railroad improve its viaducts to minimize flooding, and also established requirements that new housing developments had to increase their stormwater retention capabilities by 25% above the previous design values required. Naperville commissioned two firms to prepare new and improved contour maps in settling future flood insurance claims. Will and Kane Counties formed a joint committee to develop a regional approach to handle flooding.

Summary: Losses and costs

The July 1996 rainstorm resulted in six deaths and flooded more than 35 000 homes. However, precise assessment of the total costs of the 17–18 July rainstorm is not possible.

Two approaches were used to estimate the storm losses. One was based on a combination of federal payouts ($255 million), state and local matching payouts ($10 million), costs to the railroads ($48 million), losses in crops ($67 million), costs to repair roads and bridges ($226 million), and costs for housing and business losses not covered by government assistance ($39 million). Total costs using this approach, based on data from a variety of sources, were $645 million.

Another approach to estimate the storm costs used the estimated losses reported by the counties. These values included $140 million (Kane County), $134 million (DuPage County), $130 million (Will County),$160 million (Cook County), $26 million (DeKalb County), $15 million (Kendall County), and $31 million (all other nine counties combined). The sum of these estimates is $635 million, slightly less than the sectoral approach.

Since both approaches represent estimates from a variety of sources, it appears reasonable to assume that the flood costs ranged between $600 and $700 million. IEMA concluded that this was the second most damaging weather disaster in the state’s history, behind only the flood of 1993, which produced $1.4 billion in losses and costs for Illinois (Changnon 1996b).

Acknowledgments

This paper was funded in part by a grant/cooperative agreement from the National Oceanic and Atmospheric Administration (NOAA). The views expressed herein are those of the authors and do not necessarily reflect the views of NOAA or any of its subagencies. The review of Eva Kingston and the typing of Jean Dennison are appreciated, as is the considerable assistance of the Illinois Emergency Management Agency and U.S. Geological Survey.

REFERENCES

REFERENCES
Bhowmik, N. G., A. P. Bonini, W. Bogner, and R. Byrne, 1980: Hydraulics of Flow and Sediment Transport in the Kankakee River in Illinois. Illinois State Water Survey, 49 pp. (Report of Investigation 98.)
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Changnon, S. A., 1996a: Impacts and response to the storm. The Record Rainstorm on July 17–18, 1996, in Northern Illinois, S. Changnon, Ed., Illinois State Water Survey, 121–140. (Misc. Rep 182.)
.
——, 1996b: Losers and winners: A summary of the flood’s impacts. The Great Flood of 1993, S. Changnon, Ed., Westview Press, 276–299.

Footnotes

Corresponding author address: Stanley A. Changnon, Applied Climatology Office, Illinois State Water Survey, 2204 Griffith Dr., Champaign, IL 61820.