MSD is required, under a 2005 Consent Decree agreement with the U.S. Environmental Protection Agency, to reduce sewer system overflows that released both stormwater and untreated wastewater into local waterways during periods of heavy rain. The overflows primarily result from early sewer design that routes wastewater and stormwater together in a Combined Sewer System. These combined sewer systems were the industry standard in Kentucky until 1955 when they were banned by the state.
Projects created since then are Sanitary Sewer Systems that carry only wastewater, and Separate Storm Sewer Systems that carry only stormwater.
Existing Combined Sewer Systems across the country, such as the one inside the Interstate 264 Watterson Expressway in Louisville, were required to reduce the polluting Combined Sewer Overflows (CSOs) and mitigate their effects on the environment. They are also required to eliminate any Sanitary System Overflows (SSOs) from newer systems like those outside the Watterson in Jefferson County.
Original terms of the Consent Decree resulted in an MSD plan to reduce CSOs and eliminate SSOs at a cost of $1.15 billion for projects to be completed by 2024. The vast majority of MSD capital improvement spending was dedicated to those remedies while other general capital needs went unmet. A 2022 amendment to the Consent Decree built in those previously unmet needs and extended the completion period to 2035.
Projects added under the 2022 amended agreement
- Morris Forman Water Quality Treatment Center -- $198 million upgrade will replace an outdated biosolids processing system to increase capacity and decrease pollutants discharged to the Ohio River. Projected completion, 2030.
- Paddy's Run Pump Station -- $124 million to replace this 59-year-old facility to better protect against Ohio River flooding and combined sewage discharges. Projected completion, 2026.
- Interceptor Rehabilitation -- $70 million to replace critical large sewer lines (interceptors) that are up to 75 years old. Projected completion, 2025.
Completed Consent Decree projects and accomplishments
- $1.2 billion spent through June 2022 on storage basins, including the 4-mile Waterway Protection Tunnel, green infrastructure and other projects to reduce sewer overflows.
- 5.85 billion-gallon typical rainfall year reduction in CSO volume
- 72 percent elimination of projected 2-year storm SSOs and 82 percent elimination for 5-year storm projections
- 76 percent reduction in Ohio River fecal coliform concentration
- Nearly 18,000 plumbing modification projects to remedy residential basement backups
Additional Consent Decree Information
The MSD Project Win website includes a map of consent decree projects, a list of reports and more.