MSD's Consent Decree

Water Through Trees

MSD is under a federal mandate to reduce combined sewer overflows into local streams and rivers and eliminate sanitary sewer overflows (SSOs) during a typical year of rain (41 inches).

To date, MSD has reduced combined sewer overflow (CSO) volume by 6 billion gallons a year and invested more than $1 billion in infrastructure improvements. This is about a third of the work necessary to achieve full compliance. This initative is anticipated to take decades to complete.

Overview of Consent Decrees

To address the issue of sewer overflows and achieve compliance with the Clean Water Act, the City of Cincinnati and Hamilton County entered into two federal Consent Decrees and developed a $3.1 billion Wet Weather Improvement Plan (WWIP):

  • Interim Partial Consent Decree on SSOs, 2002
  • Global Consent Decree on CSOs and Treatment Plants, 2004
  • Wet Weather Improvement Plan (WWIP), 2010
  • Wet Weather Improvement Plan

    The Wet Weather Improvement Plan is being conducted in two phases: Phase 1 (2009-2018) and Phase 2 (after 2018).

    Phase 1 of the plan was rebranded as Project Groundwork in 2009, with a separate website and logo. Project Groundwork (click for Project Groundwork website) MSD is currently finishing up Phase 1, which includes 133 projects. Phase 1 also includes the Lower Mill Creek Partial Remedy, which is designed to reduce overflows into the Mill Creek by 1.78 billion gallons a year, primarily through the Lick Run Project. Click here for Phase 1 accomplishments to date.

    Phase 2 of Project Groundwork, which is expected to start in 2020, will be implemented in phases over multiple years, starting with Phase 2A. MSD submitted a proposed Phase 2A schedule to the U.S. EPA on June 28, 2018 on behalf of the City of Cincinnati. In the interim period between Phase 1 and Phase 2a, MSD is working on 26 wet weather projects known as the "bridge."


    In the late 1980s and 1990s, the federal government, through the Clean Water Act, called for the elimination of sanitary sewer overflows (SSOs) and a reduction of discharges from combined sewer overflows (CSOs). This action affected every wastewater system in the country, including MSD. Increased scrutiny from the U.S. Department of Justice (DOJ) and U.S. Environmental Protection Agency (EPA) brought the issue to the forefront in the late 1990s as these government bodies began enforcing the ruling in large cities and leveling heavy civil penalties on those out of compliance.

    In 1999, MSD, which had already begun eliminating SSOs and reducing CSOs, entered into negotiations with the EPA, DOJ, and the State of Ohio to establish a formal remediation program that would be recognized and supported by the government, but also was affordable for local ratepayers. These negotiations resulted in the two Consent Decrees and the Wet Weather Improvement Plan (WWIP).

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