Certified Storm Water Operator Practice Exam

What is the function of check dams in roadside ditches?

1. Increase water temperature

2. Reduce water velocity

3. Enhance sediment build-up

4. Support plant growth

The correct answer is: Reduce water velocity

Check dams are specifically designed to reduce water velocity in roadside ditches. This reduction in velocity is crucial because it helps manage the flow of water, preventing erosion of the ditch and the surrounding areas. When water flows too quickly, it can erode the soil, leading to loss of material and potential damage to the roadside infrastructure. By placing check dams at intervals, the flow is slowed down, allowing particulate matter and sediments to settle out of the water column. This sediment settle-out process is essential in improving water quality, as it diminishes the amount of sediment that could wash into larger water bodies, thereby reducing sediment pollution. By effectively maintaining lower velocities in these channels, check dams contribute to the overall stabilization of the ditch environment. While there are some connections to the enhancement of sediment build-up and supporting plant growth, those functions are more indirect consequences of water velocity reduction rather than the primary purpose of check dams. The main focus remains on the control of water flow to promote better erosion control and sediment management.