428RESTORING URBAN STREAMS recovery plants that will produce effluents with a quality on par with, or better than, the water quality in good-quality receiving waters IX.1 INTRODUCTION 429 the cities, as occurred frequently in London and many other places during the first 60 years of the last century. Consequently, after cleanup, people in the U.S. who left the cities for the suburbs have begun rediscovering urban rivers and have been slowly returning to central city living, with the real estate near the water resources at a high premium. Many cities are now calling themselves "Water Cities" and use this distinction in urban development. Chicago (Illinois) and Milwaukee (Wisconsin) on Lake Michigan, Toronto (Ontario) on Lake Ontario, Sydney (Australia), and Singapore in Asia have opened their architecture to their water bodies by preserving and restoring their waterfronts, including beaches, parks with bike and pedestrian paths, architectural monuments, museums and entertainment facilities (e.g., opera in Sydney, an art museum in Milwaukee designed by the renowned Spanish architect Calatrava, and museums in Chicago), restaurants and piers, and so on. Historically, Paris has had its Seine River, Prague has had the Vltava (Moldau) River, London is renowned for the Thames River, and Boston (Massachusetts) has the Charles River; Amsterdam, Bangkok, Venice, and several cities in China all have arch bridges and famous canals. These rivers and canals have been the lifelines of the cities, providing transportation for people and commerce, water and energy for industries developed on the shores, enjoyment and recreation opportunities for the people-but they also became a medium for disposing of wastes from the city, overwhelming their pollution-carrying capacity and, for some, leading to their demise.Today, cities are also beginning to rediscover the high economic and social value of their water bodies, large and small, transecting the urban areas. Citizens and city governments have realized that streams buried by unrestricted developments during the third paradigm, and of poor quality, have no social or economic value. As a matter of fact, the areas above and around the buried streams in most cases have deteriorated to the point of social injustice and left disadvantaged populations in the dilapidated neighborhoods. This occurred in the watershed of Stony Brook in Boston, as well as in the watershed of the Cheonggyecheon River in Seoul, Korea (see Box 9.1).
BOX 9.1 DAYLIGHTING THE CHEONGGYECHEON RIVER IN SEOUL, DEMOCRATIC REPUBLIC OF KOREAThe name Cheonggyecheon means in Korean "clean water stream," and for centuries the river provided the Korean capital city with clean water from nearby mountains and washed its waste to the much larger Han River. But at the beginning of the 20th century, when the river received its current name, it was far from clean, and plans were made a hundred years ago by Japanese colonial occupying authorities to cover the river. These plans failed because of lack of funding and wars.During the Kor...