Defense Against Rising Waters: A New Era for Louisville's Flood Control

In early 1937, the Ohio River elevated to its highest levels leading to devastating flooding in Louisville, Kentucky. Today, that historical flood, also known as the Great Flood of 1937, is still the flood of record for the area. In an effort to re- duce flooding risk to the population, the Flood Control Act of 1937 was passed to strengthen Louisville's re- silience against future flooding. This triggered the U.S. Army Corps of Engineers (USACE) to construct the Louisville Metro Levee System, which comprises 26.1 mi (42 km) of concrete floodwalls and earthen levees with 16 flood pump stations. One of those flood pump stations was the Paddy's Run Flood Pump Station, which was built in the 1950s, in the western portion of Louisville. That flood pump station was located at an existing stormwater outfall that conveys the stormwater from the western metro- politan area under the levee to the Ohio River. The stormwater flows through the outfall by gravity when the Ohio River is not elevated. When the river is elevated, the flood pump station becomes active after a flood gate at the end of the outfall closes. This is necessary because with- out the flood gate, the Ohio River would backflow into the outfall causing inland flooding. When the flood pump station is active, the stormwater gets pumped over the levee embankment through discharge pipes into the Ohio River. Stormwater can collect in a ponding area and backup during intense rainfall events when the inflow to the flood pump station exceeds the capacity. Recently, Louisville and Jefferson County Metropolitan Sewer District (MSD), which now operates and main- tains the levee system, determined the need to upgrade the existing Paddy's Run Flood Pump Station's capacity to reduce the risk of interior flooding. MSD determined the new flood pump station would need to increase existing capacity from 875 million to 1,900 million gal (4 to 8.6 billion L) a day to account for a 2035 projected storm event, which is a 10-year, 24-hour storm event of 5.0 in (127 mm) in 24 hours. Due to the age and complications associated with up- grading the existing pump station, a new pump station was selected as the preferred approach. In 2021, MSD