Tunnel and Reservoir Plan

This combined with a temperate wet climate and the human development of open land, leads to substantial water runoff.

[dubious – discuss] Between 1864 and 1867, under the leadership of Ellis S. Chesbrough, the city built the two-mile Chicago lake tunnel to a new water intake location farther from the shore.

The primary benefit of wastestream separation is that storm water requires less treatment than sewage before being returned to the environment.

Flood damage grew markedly after 1938, when surrounding natural drainage areas were lost to development and human activity.

Phase 2, creation of reservoirs primarily intended for flood control, remains underway with an expected completion date of 2029.

Severe weather events have forced water management agencies to pump excess wastewater into the lake and river in order to prevent flooding.

Long considered an open sewer, the Chicago River now hosts more than 60 fish species and increased wildlife along its shores.

On October 3, 1986, a heavy thunderstorm drenched the southern portion of the Deep Tunnel area with several inches of rain in a short period of time.

A 30 feet (9 m) geyser erupted downtown at the corner of Jefferson and Monroe, trapping a woman inside her car as it filled with water.

[citation needed] Since the tunnels became operational, combined sewer overflows have been reduced from an average of 100 days per year to 50.