Civil Engineering Professional Engineer Practice Exam 2025 - Free PE Practice Questions and Study Guide

The purpose of a retention basin in stormwater management is primarily to hold stormwater runoff and release it slowly. This controlled release helps mitigate the risk of flooding and reduces the potential for erosion and water quality degradation by allowing sediment and pollutants to settle before the water is discharged into natural waterways.

Retention basins are designed to hold water for a longer duration, thereby providing both temporary storage and treatment of stormwater. This slow release is crucial because it aligns with the natural hydrological cycle, allowing for groundwater recharge and improving overall water quality by reducing peak flow rates and the volume of pollutants carried into surrounding ecosystems.

Other options such as quick-release features, agricultural irrigation, or solely pollutant filtering do not reflect the primary function of a retention basin in managing stormwater. Each of these choices highlights different aspects of water management, but they do not capture the essential role retention basins play in promoting gradual drainage and enhancing water quality.