In 1993, DuPage County began converting an old quarry in Illinois into a reservoir for Salt Creek floodwater threatening communities; the facility can hold 8,300 acre-feet, or about 2.7 billion gallons

DuPage County, Illinois, began converting the former Elmhurst-Chicago Stone quarry into a flood-control facility in March 1993, creating a reservoir designed to store excess water from Salt Creek during periods of high water. According to DuPage County Stormwater Management, the reservoir can hold water up to 8,300 acre-feet, equivalent to approximately 2.7 billion US gallons. After the county purchased the quarry in 1992, the facility became operational in 1996, and it is located south of North Avenue along Illinois Route 83 in Elmhurst.The flood that changed the quarry’s purposeAfter severe flooding in Elmhurst in August 1987, the decisions to acquire the quarry were set in motion. Oak Brook Magazine reported that within the 12 hours on August 13 and 14, 9.5 inches of rain fell, which caused the Salt Creek to rise from its average level of 2.4 feet to 12.85 feet. The resulting consequence included an estimated damage of $33 million at the time, with roads, homes, and businesses being affected.According to the same report, the Elmhurst History Museum recorded more than 50,000 sandbags filled by the Department of Public Works, while the fire department and police department handled 1,745 and 2,000 calls, respectively. Governor Jim Thompson issued a disaster declaration, while President Ronald Reagan authorised federal emergency assistance. In addition, the National Guard and Red Cross had also responded.The Elmhurst History Museum, as cited by Oak Brook Magazine, estimated that the facility had helped save approximately 4,000 homes from flooding. The quarry's earlier industrial history began in 1883, when, during well drilling, limestone was discovered near the surface. The Hammerschmidt family developed the Elmhurst-Chicago Stone Company, which supplied limestone for building foundations and walls. The company later pivoted towards creating ready-mixed concrete from crushed stone, which was used in regional infrastructure, including major expressways. The county's acquisition changed the quarry's function without removing its existing geological structure. Its two excavated sections, known as the east and west lobes, became the principal storage areas in the flood-control system.Inside the quarry’s floodwater systemWhen Salt Creek approaches flood stage, excess water goes through a diversion channel that leads to a drop shaft,then it falls into a 400-foot tunnel beneath Route 83 and enters the west lobe. From that point, the water passes through a rock opening known as the keyway into the east lobe, which has an average depth of 200 feet, with its deepest point reaching 240 feet.A high rock wall separates the two sections and supports West Avenue, except where the keyway lets the water pass between them. A seven-foot-square steel sluice gate controls the diversion of water from Salt Creek, which officials can operate on site or remotely. The system also includes a concrete barrier, known as a weir, over which water can flow when creek levels rise sufficiently.Once stored in the quarry, the water remains there until creek levels recede, after which it is returned to Salt Creek by pumping through an aerating structure. The system is designed to manage the release of stored water at controlled flow rates as part of the wider flood-control operation. The facility also supports flood management beyond Elmhurst as Salt Creek is part of a wider watershed, so managing excess water at the quarry contributes to conditions further downstream. Its role extends beyond storing water within the excavation and may provide a means of managing high flows across a connected system of communities.You use AI every day. Now get your AI Quotient. Take the AIQ test.