The MWRD's main purposes are the reclamation and treatment of wastewater and flood water abatement in Cook County to protect the health and safety of citizens and of area waterways.

The MWRD is governed by a nine-member Board of Commissioners elected at large from throughout Cook County, Illinois for six-year terms.

There are eight departments: Engineering, Finance, Human Resources, Information Technology, Law, Maintenance and Operations, Monitoring and Research, and Procurement and Materials Management.

Heads of these departments report to the Executive Director as do the staff and support units of Administrative Services which includes the Diversity, Environmental Justice, Management and Budget, and Public Affairs sections.

Public meetings are held twice per month (except during July and August) in the board room at 100 E. Erie Street, Chicago, IL.

Although the District's first assignment in reversing the flow of the river and constructing a vast network of waterways was clear, establishing itself was the first hurdle.

The chance to promote economic development linking the Great Lakes to the Gulf of Mexico ultimately persuaded the rest of the state to adopt legislation.

On May 29, 1889, the General Assembly approved “an Act to Create Sanitary Districts and to Remove Obstructions in the Des Plaines and Illinois Rivers.” The Enabling Act required a referendum establishing the boundaries of the District, roughly covering 185 square miles from the lakefront west to Harlem Avenue and from Devon Avenue on the north to 87th Street on the south.

The MWRD constructed 560 miles of intercepting sewers and force mains ranging in size from 6 inches to 27 feet in diameter.

The water flowing through the facility is harnessed by 2 turbines to provide a safe and environmentally friendly hydroelectric energy source that is sold back to Commonwealth Edison.

It also shares responsibility with the Army Corps of Engineers for the Chicago Area Waterway System (CAWS), including the Chicago Sanitary and Ship Canal and approximately 76 miles (122 km) of waterways, part of a national system connecting the Atlantic Ocean, Great Lakes, and the Gulf of Mexico.

It includes over one hundred miles of tunnels, 9 to 33 feet (10 m) in diameter, each part of an extensive flood mitigation and pollution control project.

Located along interstate 80 in southern Cook County, the Thornton Composite Reservoir, an important component of the MWRD's TARP, went into operation on December 31, 2015.

The Thornton Composite Reservoir came online at the same time as disinfection facilities at the MWRD's Calumet Water Reclamation Plant in Chicago, which also serves the southern area of the county.

The WMO provides uniform stormwater management regulations for Cook County in order to prevent future commercial, municipal, and residential development and redevelopment projects from exacerbating flooding.

By March, 2012, the MWRD selected the optimal technology for disinfecting the treated water at the Calumet and O'Brien Water Reclamation Plants after a blue ribbon task force evaluated all available disinfection technologies using a triple bottom line approach that considered economic, environmental and social criteria.

[12] On Sept. 16, 2013 former U.S. Environmental Protection Agency Region 5 Administrator Susan Hedman, former Illinois Environmental Protection Agency Director Lisa Bonnett, State Rep. Robyn Gabel, Skokie Mayor George Van Dusen and other area representatives joined the MWRD Board of Commissioners to break ground on the disinfection facility at the O’Brien WRP.

Senators Richard Durbin and Mark Kirk and Congressman Mike Quigley toured the Chicago area waterways and announced their support for the disinfection projects.

Algae naturally uptakes phosphorus and nitrogen from water to support its growth through photosynthesis, utilizing the sun as its energy source.

The algae could remove at least 50 percent of phosphorus from wastewater and can be harvested and commoditized for production of bioplastics, biochemicals, biofuels, pharmaceuticals and dyes; or used as fertilizer or as aquaculture feed.

This could potentially stimulate the Chicago regional economy by locating a plastics partner near the treatment plant and reduce reliance on petroleum.

The MWRD is supporting leading-edge research in this field to help make algae technology a practical and sustainable approach to nutrient management for urban wastewater treatment plants.

During the water treatment process, the greenhouse research facility at the O’Brien WRP employs a technology called revolving algae biofilm reactors designed by Iowa State University scientists who originally applied it for agricultural applications.

Biosolids are an environmentally friendly product of the water treatment process that supplies organic matter and improves soil structure and porosity to allow plants to more effectively utilize nutrients.

Under the Illinois Environmental Protection Act, signed into law in 2015, biosolids were formally recognized as a safe, beneficial and renewable resource that should be used locally.

Air-dried biosolids look and feel like dark, fine-textured topsoil, and are used on turfgrass at golf courses, athletic fields, parks and other recreational areas, and for restoration of brownfields and other disturbed lands.

The compost is produced in windrows that are maintained at a temperature of at least 131 degrees for a minimum of 15 days and are turned five times during the period as required in USEPA protocol.