In addition to the creation of more wastewater, urban areas add to poor water quality in a number of ways. The high concentration of impervious surfaces increases runoff from roads and can carry numerous pollutants such as oils, heavy metals, rubber, and other automobile pollution into waterways and streams. The reduction in water percolation into the ground can also affect the quantity and quality of groundwater. Stormwater runoff in urban areas can overwhelm combined stormwater and wastewater treatment systems when high volume flows exceed treatment capacities. With more people, there will be a need for increased agricultural productivity. Enlargements in irrigated.
