Montana Earth Science Picture of the Week

Storm drains like the one shown in this photo are a common site in all of Montana's cities and some of its smaller towns. This one is located near Helena High School. The gym can be seen in the background.

The purpose of a storm drainage system is to drain water off of the streets during periods of rainfall or snowmelt. Paved streets, parking lots, buildings, and driveways reduce the area where water can soak into the ground. A s result of this decreased infiltration, runoff is increased. This can lead to flooding, especially in lower parts of town,

Storm drainage does not go to a wastewater (sewage) treatment facility. Instead, pipes deliver it to a nearby river or area of land set aside to receive it. . . In Helena pipes deliver the water to an area north of K-Mart where it soaks into the ground. Cattails and other wetland plants soak up the water. As the water runs off of streets, driveways, and parking lots, it picks up motor oil, and antifreeze, taking them to the stream. In order to protect the health of streams and wetlands, it is important not to dispose of unwanted liquids by pouring them into the street or into a storm drain.

Terms: infiltration, wetland