In the past, wetlands were considered wastelands because people could not build homes or other buildings on them. During the early settlements, people drained many swamps in order to build railroads and roads or to develop farmland, thereby destroying the natural wetland environment. As conservation practices have become more widely accepted, and people have learned more about their natural environment, the true value of wetland resources has begun to be recognized. Wetlands have the ability to help control flooding. Because they act like giant, shallow bowls, water collects in them and slows down as it spreads out, making flood management much easier. They then slowly release floodwaters back into streams, lakes, and groundwater, making flooding impacts less damaging. One acre of wetlands can store more than 360,000 gallons (1,362,748 liters) of water if flooded to a depth of one foot (0.3 m). This helps reduce property damage and loss of life in the United States when winter snow melts and becomes spring runoff.