MARBLE ROCK WWTP - Secondary Treatment Plant in Floyd County, Iowa

MARBLE ROCK WWTP is a municipal wastewater treatment facility located in Floyd County, Iowa, United States. The plant serves a small population of 361 residents, reflecting its role in a rural community. It is situated near the Upper Greene Road area, within the state's agricultural landscape. The plant provides secondary treatment, a standard biological process that removes organic matter and suspended solids. With a designed capacity of 227.12 megaliters and an annual discharge volume of 189.27 megaliters, it operates below its capacity. As a U.S. facility, it is subject to the Clean Water Act and National Pollutant Discharge Elimination System (NPDES) permitting, which sets effluent limits to protect water quality. The treated effluent is discharged into local waterways, likely tributaries of the Cedar River or the Iowa River, which eventually drain into the Mississippi River. This contributes to the broader Mississippi River Basin, supporting downstream ecosystems and water resources in the Midwest.

The plant's discharge enters local streams in the Cedar River watershed, which flows into the Iowa River and then the Mississippi River. This region supports diverse aquatic life, including fish and macroinvertebrates, and the Mississippi River is a critical migratory corridor for birds and fish. The secondary treatment helps reduce nutrient loads, protecting downstream water quality in the Gulf of Mexico.