In Charleston, a rising tide works its way up a low-lying storm drain from the nearby harbor - taking with it oils, debris, and other forms of pollution as it eventually subsides. This video was taken during a period of flood conditions in the region. The water seen is not rain water, but instead, it is salt water intruding up the city's drainage system.
It is not uncommon for Lowcountry residents to experience flooded streets during heavy rains. Because of the sheer amount of pavement, concrete, and developed surfaces along the region's waterfront (also known as impervious surfaces), stormwater and floodwater does not naturally absorb into the ground; instead, it gathers pollutants in the process and recedes back to our waterways slowly contaminating our rivers, creeks, and harbor.