The Monarch-Chesterfield Levee was built to protect Chesterfield and nearby communities from flooding by the Missouri River and its tributaries. During the Great Flood of 1993, which inundated the Midwest, more than 1,000 levees failed, 70,000 buildings were damaged, 50 people died, and losses reached at least $12 billion. On July 30, 1993, at 10:17 p.m., the Missouri River ruptured the Monarch Levee, and floodwaters poured through a 100-foot break, filling Chesterfield Valley with more than eight feet of muddy water and debris. In 1994, work began to raise the levee from 100-year protection to 500-year protection by increasing its height, widening it, and adding seepage berms, gates, and flood walls. After the flood, some businesses left, but others stayed, and Chesterfield created a tax-increment financing district to rebuild the levee and revive the valley, which later became a major retail area. The Monarch-Chesterfield Levee Trail became a central part of the city parks, recreation, and trail system and of the Missouri River Greenway, with a planned 17-mile route, about 12 miles of it on the levee within the 4,100-acre Chesterfield Valley, linked to on-street bike paths, sidewalks, and walking paths. Along the river, Chesterfield and the Monarch-Chesterfield Levee District also sponsored a 130-acre wetland mitigation project, completed over two years, that created wetland sites north of Highway 40 and was monitored to ensure success. These wetlands help regulate river flow, absorb and store water, filter pollutants, control erosion, support wildlife habitat, generate nutrients for freshwater life, and replenish groundwater. The area supports migrating waterfowl, wintering bald eagles, the endangered American bittern, endangered fish including the pallid sturgeon, the endangered Indiana bat, wetland trees such as black willow, cottonwood, sycamore, slippery elm, green ash, and silver maple, and many mammals, reptiles, and amphibians typical of wetland habitat. Stewardship efforts in the broader floodplain include the Big Muddy National Fish and Wildlife Refuge, established in 1994 to preserve and restore Missouri River floodplain habitat, its Boone's Crossing unit, and restoration work by the Zahniser Institute. The valley also includes major recreational facilities such as the 142-acre Chesterfield Valley Athletic Complex, used by more than 350,000 people each year and home to Miracle Field for children with disabilities.