AS water flows into rivers, lakes, and estuaries, or into the ground, it collects in low areas, forming marshes, swamps, and bogs. Water overflows riverbanks during storms, saturating neighboring land. And most rivers, lakes, and estuaries naturally have undefined boundaries. Instead of stopping at a packed bank, like canals, natural water bodies tend to merge slowly and irregularly into land.The areas that are not deep but only saturated and temporarily inundated are the nation's wetlands. Legal protections have evolved to protect them for one simple reason: Wetlands are essential to preserve aquatic life and pure water. Aquatic animals need to eat. Their food chain begins with the wetlands, which include some of the most biologically productive areas on the planet. Coastal salt marshes created by the flooding of ocean tides produce four times more food per acre than the most highly productive wheat fields. Fish also need areas in which to breed. Most of the commercial fish eaten in the United States depend on wetlands. The vast majority of waterfowl also need wetlands to feed and breed. Wetlands also maintain the natural purity of the water. As rainwater flows off the land and into the lakes, rivers, and bays, it carries sediment, phosphates, and nitrogen, and more recently, artificial pollutants created by man. Wetlands absorb many of these pollutants which could choke the water body. Just as industrial waste in water can pollute an estuary or river, so can elimination of wetlands surrounding it. Indeed, as wetlands have been filled and drained, industry and homeowners have had to spend more money to clean up their sewage just to compensate for the loss of natural pollution control. The new Bush administration proposal to redefine wetlands would eliminate protection for roughly 30 million acres, according to preliminary estimates by government scientists. The Environmental Defense Fund has calculated that equivalent, artificial pollution control would cost a minimum of $100 billion. Wetlands serve a variety of functions in physically controlling how water flows. They provide nature's flood protection; after developers fill in wetlands, localities often find themselves turning to government to construct expensive flood control systems. Many wetlands allow rainwater to filter into the ground and to replenish drinking water aquifers. Wetlands also control shoreline erosion, protecting against losses of land, reduced navigation, and burial of wildlife habitat. When Congress passed the Clean Water Act in 1972, its broad goal was to "restore and maintain the chemical, physical, and biological integrity of the nation's waters.Integrity," the US Supreme Court has stated, "refers to a condition in which the natural structure and function of ecosystems [are] maintained." Wetlands were included in the Act, not as a separate category, but simply as part of US water bodies. Since 1972, scientists have provided more and more evidence of how wetlands are "integral parts of the aquatic environment," and "inseparably bound up with 'waters' of the United States," as the Supreme Court has written. Congress has explicitly rejected efforts to eliminate wetlands protection in the Clean Water Act. Despite the legal protections of the Clean Water Act and similar state statutes, America continues to lose wetlands to filling and draining at a rate of 30 acres per hour. Lax government enforcement of the Clean Water Act is primarily responsible. The continental US has already lost more than half of its original 221 million acres of wetlands. In 1987, industrialists, environmentalists, and politicians brought together to study the problem recommended a policy of no further overall loss of wetlands. This policy was endorsed by the National Governors' Association in a bipartisan resolution, and it formed the core of President Bush's campaign platform on the environment. Common sense and the public good seemed to prevail. But the oil companies, who find the restrictions burdensome in some states, and developers, who covet cheap land, have mounted a counterattack. Farming is largely exempt from wetlands laws, but some farmers who wish to sell their wetlands to developers have given their support. These interests have gained support from some members of Congress and persuaded Bush to abandon his campaign pledge and to propose defining away 30 percent of the nation's wetlands. Lost areas would include large portions of core ecosystems, like the Florida Everglades, the saturated forests of the east coast, and possibly the forested wetlands of the Mississippi Valley. Wildlife in drier western areas, which have even fewer remaining wetlands, may suffer even more. Recent publicity has started to slow the industry attack. This country can only fulfill the goals of the Clean Water Act by strengthening wetlands protection, not gutting it.