ULI examines connection between land use, water use

The shrinking supply of water in many areas of the United States points to the need for more efficient land use and sustainable development techniques that help conserve water and encourage replenishment of water resources, according to participants at a December urban growth forum sponsored by the Urban Land Institute.

The forum, which focused on the impact of urban development on water quantity and quality, included observations from a variety of real estate industry professionals, including developers, urban designers, architects, academics and public sector officials.

Participants agreed that while there is no national water crisis, regional and local problems with both water quantity and quality will continue without a broad-based cutback in public water consumption and a change in development patterns.

Charles Groat, director of the U.S. Geological Survey in Reston, Va., opened the forum with an overview of the nation's water supply, showing how the way land is used whether for agricultural purposes or urban purposes directly affects the availability of usable water.

"It's clear that over the past 50 years, the urban footprint has had an impact that rivals the forces of nature in changing the environmental landscape," Groat said.

USGS data shows that between 1950 and 1980, U.S. water use rose from about 160 billion gallons per day to about 370 billion gallons per day, far outstripping the U.S. population growth, which rose during that period from 150 million to a little more than 200 million people. Since 1980, water use has declined, leveling off to about 330 billion gallons per day, even though the population has continued to rise to more than 288 million people. However, Groat noted, the decline is due to conservation measures for irrigation and thermoelectric power production; domestic and public water use has continued to rise.

As more land becomes urbanized and less land is used for agriculture, water use is certain to increase, straining fresh water sources both above and below ground, he said. Moreover, inefficient water use leads to saltwater intrusion in rivers and aquifers, and to land subsidence, in which the absence of water in the soil causes it to crack and sink several inches, Groat said.

"As urban areas spread outward, we'll see increased challenges in maintaining water quality and quantity," he said. "Even in areas where replenishment is not now a problem, (the ability of the water source to replenish itself) will be diminished by paving over the ground."

While the scarcity of water has long been acknowledged in the arid West, Groat said several urban areas in the East are showing signs of a diminished supply, as more wells on the East Coast are abandoned due to high salt content, and more desalination projects are built.

Susan A. Maxman, president of Susan Maxman and Partners Architects in Philadelphia, described alternative building and drainage strategies that mimic nature's ways of returning water to the earth, and reduce the creation of impervious surfaces, which hamper the ability of water to seep back into the ground.

Such processes include using wetlands as natural water filtration systems; using only indigenous vegetation for landscaping so the plants don't need extra water; using more porous material for pavement, and using more French drains and fewer curbs and gutters, to channel more runoff directly into the ground, rather than into storm drains. These methods and others are examined in detail in ULI's publication "Toward More Sustainable Development," which Maxman co-authored with other environmental and land use experts.

"We need to be doing more to work with the land, not against it. Returning water back to the land and not having it go down a sewer pipe is an issue we all have to think about," Maxman said. "If developers understood more about the natural process, that a natural fix is better than a man-made fix, they would see that natural solutions (such as the inclusion of a constructive wetland) can serve as a true amenity to a development," she said.

Forum participants agreed that water quantity and quality are critical issues that support "smarter" development clustered, mixed-use projects that decrease the amount of land needed for live-work-play space. The prevalence of low-density, segregated use, auto-dependent development in the United States is putting pressure on the water supply systems, just as this type of development is straining the transportation and infrastructure systems, they noted.

"We will likely see more emphasis on smart growth techniques as they apply to water conservation," said A. Dan Tarlock, professor of law and co-director of the program in environmental and energy law at Chicago-Kent College of Law, Illinois Institute of Technology in Chicago.

According to Tarlock, as municipalities find themselves searching for new water sources to serve their growing populations, more collaborative approaches to providing water are likely.

"Cities need to realize they are part of a larger aquifer and watershed then new relationships with other jurisdictions can be formed so they can work together to conserve water," he said.

Despite the rising concerns over water quantity and quality in the United States, water remains less expensive here than in other countries. Increased pricing would act as an incentive to conserve use on individual, project development and municipal consumption levels, forum participants concluded.

The Urban Land Institute is a nonprofit education and research institute supported by its members. Its mission is to provide responsible leadership in the use of land in order to enhance the total environment.