The City of Sioux City is served by a municipally-owned, 28.73 million gallon per day wastewater plant located at 3100 South Lewis Blvd. near the intersection of Interstate Highway 29 and U.S. Route 20.

Originally constructed in 1961, the Sioux City Regional Wastewater Treatment Plant serves five communities from three different states, including:

• Sioux City, IA
• Sergeant Bluff, IA
• South Sioux City, NE
• North Sioux City, SD
• Dakota Dunes, SD