Combined Sewer Overflow (CSO)
Definition
A system where stormwater runoff and sewage flow through the same pipes to treatment plants. During heavy rain, these combined systems overflow, releasing untreated sewage and polluted stormwater directly into rivers and streams. Louisville has one of the nation’s largest CSO problems with 55 overflow points that discharge approximately 9 billion gallons of untreated sewage and stormwater into the Ohio River annually.
Louisville Context
Louisville’s CSO system was built 100+ years ago when this design was standard practice. A 2005 federal consent decree requires Louisville to reduce overflows by 98% by 2025. MSD is spending over $1 billion on the Waterway Protection Tunnel and other infrastructure to meet this deadline, with costs passed to ratepayers through sewer bills.
Why It Matters
CSOs contaminate Louisville’s waterways with raw sewage, creating public health risks and environmental damage. The massive infrastructure investments to fix this problem directly impact your monthly sewer bills, which have tripled since 2005 and will continue increasing.
Dave’s Proposal
Dave supports completing CSO elimination on schedule while maximizing green infrastructure solutions that provide community benefits (parks, rain gardens, tree canopy) rather than only underground tunnels. He’ll advocate for MSD to pursue federal infrastructure grants to reduce ratepayer burden.