More than 5 billion gallons of untreated combined rainwater and wastewater overflowed into our waterways each year before a 2005 federal consent decree required MSD to develop and implement a plan to reduce sewer overflows. The Waterway Protection Tunnel is the largest of multiple basins MSD built in response.
When the volume of rain and wastewater exceeds the capacity of our Water Quality Treatment Centers, the resulting overflows are stored in the basins instead of being allowed to flow untreated into area waterways. As capacity becomes available, the water is pumped to the centers for treatment before being released to the Ohio River. The Waterway Protection Tunnel is a $201 million marvel of engineering that was completed and put into service in June of 2022.
Waterway Protection Tunnel Facts:
- Four miles long
- Part of it is below the Ohio River
- 220 feet below ground (approximately 18 stories)
- Diameter is 20 feet plus a 12-inch concrete shell
- Can hold 55 million gallons at once, equal to 83 olympic swimming pools
- Prevent 439 million gallons of overflow in a typical year
