Metropolitan Water Reclamation District of Greater Chicago

The Metropolitan Water Reclamation District of Greater Chicago (MWRD) is an independent special-purpose government agency responsible for treating wastewater and managing stormwater across Cook County, Illinois. Established under Illinois state law, the MWRD operates one of the largest water reclamation systems in the world, serving approximately 10.35 million residents across 133 municipalities (MWRD About Us). This page explains the agency's legal structure, operational mechanisms, the scenarios in which its authority is most directly felt, and the boundaries separating its jurisdiction from that of other regional bodies.

Definition and scope

The MWRD is a unit of local government organized under the Metropolitan Water Reclamation District Act, codified at 70 ILCS 2405, enacted by the Illinois General Assembly. The agency is governed by a nine-member Board of Commissioners elected to staggered six-year terms, making it one of the rare special-purpose districts in the Chicago region with direct voter accountability rather than appointive governance.

The district's core mandate covers two primary functions:

  1. Wastewater treatment — collecting and treating sanitary sewage from residences, commercial properties, and industrial facilities throughout its service area before discharge into area waterways.
  2. Stormwater management — planning, constructing, and operating infrastructure to reduce flooding caused by surface runoff, particularly through the Tunnel and Reservoir Plan (TARP), colloquially known as the "Deep Tunnel."

The MWRD operates seven water reclamation plants, the largest of which is the Stickney Water Reclamation Plant in Cicero, Illinois — the largest wastewater treatment plant in the world by design capacity, rated at 1.44 billion gallons per day (MWRD Stickney Plant).

Scope limitations: The MWRD's jurisdiction is coextensive with Cook County's boundaries. It does not govern drinking water supply — that function falls to the Chicago Department of Water Management for the City of Chicago, and to individual municipal utilities elsewhere in the county. The MWRD does not serve DuPage, Lake, Kane, Will, or McHenry counties; stormwater and wastewater governance in those collar counties is handled by separate county and municipal authorities covered in the collar counties overview.

How it works

The MWRD's wastewater collection process begins not at the treatment plant but at the municipal sewer systems that discharge into its intercepting sewers — large underground pipes that route combined and separated sewage flows toward one of the seven treatment facilities. From there, treatment proceeds through a staged process: preliminary screening, primary settling, biological secondary treatment, and disinfection before effluent is discharged into the Chicago River system, the Calumet River, or the Des Plaines River.

TARP, the stormwater control infrastructure initiated in the 1970s and largely completed in phases through 2015, consists of 109 miles of tunnels bored through dolomite rock as much as 350 feet below street level, connecting to three reservoir sites with a combined storage capacity of 20.33 billion gallons (MWRD TARP Overview). When major storm events exceed sewer capacity, TARP absorbs the overflow and releases it gradually to treatment plants, sharply reducing combined sewer overflow (CSO) events into Lake Michigan and the river system.

Funding for operations comes primarily from property tax levies on Cook County parcels, supplemented by user fees charged to industrial dischargers. The MWRD sets its levy annually through a budget process subject to Illinois Property Tax Extension Limitation Law (PTELL) constraints.

Common scenarios

The MWRD's authority becomes operationally significant across a range of situations that residents and municipalities encounter:

  1. Basement flooding complaints — When a homeowner experiences sewer backup during heavy rain events, the question of jurisdiction depends on whether the failure is in the private lateral, the municipal sewer, or the MWRD interceptor. The MWRD handles failures in its own intercepting sewer infrastructure; municipal systems and private laterals fall under separate responsibility.

  2. Industrial pretreatment permits — Manufacturers, food processors, and other industrial facilities that discharge effluent to the sewer system must obtain permits from the MWRD under its Industrial Waste and Pretreatment Program, which sets discharge limits aligned with U.S. EPA regulations under 40 CFR Part 403 (EPA Pretreatment Standards).

  3. Municipal stormwater planning — Municipalities within Cook County coordinate with the MWRD on local stormwater ordinances, floodplain regulations, and infrastructure projects, since the district's Watershed Management Ordinance (WMO) establishes minimum standards for development-related runoff and retention.

  4. Biosolids and resource recovery — Treated sludge from the reclamation process is converted into biosolids and marketed commercially under the brand name "Biosolite" for agricultural and landscaping use, representing both a disposal solution and a revenue stream (MWRD Biosolids Program).

Decision boundaries

The MWRD and the Chicago Department of Transportation both interact with street-level infrastructure, but their authorities diverge sharply: CDOT governs street surfaces and combined sewer inlets as capital improvements, while the MWRD governs what happens to flow once it enters the interceptor network.

A key distinction separates the MWRD from the Illinois Environmental Protection Agency (IEPA). The MWRD operates under National Pollutant Discharge Elimination System (NPDES) permits issued by the IEPA under authority delegated from the U.S. EPA. The MWRD is the permittee and must meet effluent quality standards; the IEPA is the permitting and enforcement authority that can compel compliance if discharge standards are violated.

Compared to the Chicago Metropolitan Agency for Planning, which coordinates land use and transportation planning across a six-county region, the MWRD has narrower geographic scope (Cook County only) but deeper operational authority within that footprint — holding rate-setting power, taxing authority, and direct infrastructure ownership that a planning body does not possess.

Residents and civic stakeholders seeking context on how the MWRD fits within the broader network of Chicago-area special-purpose districts and elected governments can find foundational orientation at the site index, which organizes coverage across the region's institutional landscape.

References

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