BACKGROUND

In the late 1980s and 1990s, the U.S. EPA, through the Clean Water Act, called for eliminating sanitary sewer overflows (SSOs) and reducing combined sewer overflows (CSOs) into local waterways. This action affected every wastewater utility in the country, including MSD.

 

Increased scrutiny in the late 1990s from the U.S. Department of Justice (DOJ) and U.S. EPA brought the issue to the forefront as they 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. These negotiations resulted in two Consent Decrees and a Wet Weather Improvement Plan (WWIP), which are collectively known as our Wet Weather Program.

 

CONSENT DECREES

MSD is under two Consent Decrees:

 

• Global Consent Decree (2004) On June 9, 2004, the the City of Cincinnati and Hamilton County entered into a Global Consent Decree with the U.S. EPA, Ohio EPA, and the Ohio River Valley Water Sanitation Commission (ORSANCO). This global decree covered Combined Sewer Overflows (CSOs), Wastewater Treatment Plants, and Implementation of Capacity Assurance Program Plan for Sanitary Sewer Overflows. The decree was lodged with the United States District Court for the Southern District of Ohio, Western Division.
  • Global Consent Decree (2004)
  • Exhibits
• Interim Partial Consent Decree (2002) On February 15, 2002, the City of Cincinnati and Hamilton County entered into an Interim Partial Consent Decree on Sanitary Sewer Overflows (SSOs) with the U.S. EPA, Ohio EPA, and the Ohio River Valley Water Sanitation Commission (ORSANCO). The decree was lodged with the United States District Court for the Southern District of Ohio, Western Division.
  • Interim Partial Consent Decree (2002)
  • Exhibits

 

WET WEATHER IMPROVEMENT PLAN (WWIP)

In August 2010, the U.S. EPA approved MSD's Wet Weather Improvement Plan (WWIP), a >$3.1 billion (in 2006 dollars) roadmap for reducing CSOs, eliminating SSOs, and addressing sewer backups.

 

• Original Wet Weather Improvement Plan (2010)

 

 

 

The WWIP is being conducted in phases:

 

• Phase 1 (2009-2020): Phase 1 began in 2009 and was substantially completed in January 2020 at a cost of $1.08 billion (in 2024 dollars). Phase 1 included 133 wet weather projects ranging from sewer replacements and sewer separations to pump station eliminations and treatment plant upgrades. Of those projects, 20 were focused on the lower reaches of the Mill Creek where a disproportionate number of CSO outfalls are located, including CSO 5, then the largest volume overflow point in MSD’s service area. The most recognized project, the Lick Run Greenway in South Fairmount, looks like an urban park with a surface stream but significantly reduces overflows from CSO 5. In total, Phase 1 has eliminated nearly 8 billion gallons annually of sewer overflows from across MSD's service area. VIEW THE LIST OF PROJECTS COMPLETED DURING PHASE 1 
• Bridge Plan (2018-2024): The Bridge Plan, an interim phase between Phase 1 and Phase 2A, began in 2018 and was substantially completed in 2024. The Bridge Plan included 26 wet weather projects ranging from CSO eliminations and sewer separations to improvements to the SSO 700 high-rate treatment facility and pump station upgrades. Information on the Bridge Plan can be found in the Consent Decree Quarterly Reports on our Progress page. BRIDGE PLAN INFO 
• Phase 2A (2023-2024): Phase 2A began in 2023 and was substantially completed in 2024. Phase 2A included the construction of three projects: the Mill Creek WWTP Diversion Chamber, CSO 402-406 Regulator Improvements, and the Little Miami WWTP Standby Power project. It also included design of two projects: a new influent pump station at the Mill Creek WWTP to serve a future High-Rate Treatment (HRT) facility and planning for improvements to the East Branch Muddy Creek Interceptor and associated pump stations. Information on Phase 2A can be found in the Consent Decree Quarterly Reports on our Progress page. PHASE 2A INFO 
• Phase 2B: A proposed Phase 2B plan was submitted by Hamilton County to the Regulators on June 28, 2024 View the proposed Phase 2B plan