Water conservation practices are just one component of a sustainable and resilient water system. The public’s relationship with and influence on their water system extends far beyond the boundaries of improved efficiency. In particular, land use practices are closely related to water supply availability, ecosystem health and water quality. Looking to the future, communications around land use issues will be an increasingly important touch-point between water managers and their customers, and it is an area of growing interest in the broader environmental community.
Land use patterns are a leading cause of urban water pollution in the United States. Large amounts of paved and impermeable areas in cities and suburban communities lead to large pulses of storm water runoff when it rains, which is associated with a multitude of cascading issues:
- Combined sewage and storm water pipes combined with large precipitation events regularly cause wastewater volumes to exceed capacity. This leads to discharge of untreated sewage and storm water into nearby water bodies.
- For separate storm water and sewage treatment systems, storm water carries fertilizers, pesticides, garbage and urban contaminants through storm drains directly to surrounding rivers, drinking water reservoirs and coastal areas. This causes degradation of recreational water bodies and drinking water supplies.
- In cities with adjacent rivers and streams, pulses of storm water moving quickly into stream channels often overwhelm the system’s ability to deal with the excess water, which triggers local flooding events. These storm water pulses can also cause erosion and manipulation of streams channels, which degrades habitat for critical aquatic species.
In the United States, an estimated 10 trillion gallons of untreated storm water runs off roofs, roads, parking lots and other paved surfaces each year. For example, a one-inch rainstorm in Los Angeles County can result in more than ten billion gallons of runoff flowing into the urban storm drain systems, and most of that water flows into the Pacific Ocean. That’s over 30,000 acre-feet of water, or about 5 percent of the region’s total annual water consumption, from just one modest rain event. While storm water is typically treated as a waste stream, onsite retention of storm water presents a unique opportunity to utilize local water supplies while reducing environmental damage and cutting infrastructure costs. This management technique is frequently referred to as green infrastructure.
Green infrastructure uses vegetation, soils and natural processes to manage water and create healthier urban environments. Examples of green infrastructure include green roofs, street trees, rain barrels, rain gardens and permeable pavement. Onsite retention of storm water through green infrastructure simultaneously improves water quality, reduces water waste and protects neighboring water bodies.