TRANSPORTATION - BTS - Bureau of Transportation Statistics

Invasive Species: Transportation influences water resourcesnot only as a result of physical infrastructure, but also as ameans by which species can be transferred between distinctecosystems. One example of this type of problem is the zebramussel. Zebra mussels are part of an environmental threat ofinvasions by non-indigenous species brought on, in part, bythe increasing level of global commerce. Zebra mussels arethumbnail-sized freshwater mollusks that arrived in theUnited States through ship ballast water in 1986 and areprojected to cause $5 billion in economic disruption to theGreat Lakes region by the end of the year 2000. Since theirdiscovery in Lake St. Clair in 1988, zebra mussels havespread throughout the Great Lakes; the Arkansas, Hudson,Illinois, Mississippi, Mohawk, Ohio, St. Lawrence, andTennessee rivers; and other waters of southern Canada andthe eastern United States. They also have been intercepted onboat trailers at four points in California.“In its path, sprawl consumesthousands of acres of forests andfarmland, woodlands and wetlands.It requires government tospend millions extra to build newschools, streets, and water andsewer lines. In its wake, sprawlleaves boarded up houses; vacantstorefronts; closed businesses;abandoned, and oftencontaminated, industrial sites;and traffic congestion, stretchingmiles from urban centers.”Maryland GovernorParris N. GlendeningA New Smart Growth Culture for MarylandThe mussels attach themselves to various surfaces, such as rocks, aquatic weeds, and industrialand residential water intake pipes. They rapidly form large reefs, reducing or blockingwater flow through pipes used for municipal drinking water facilities, electric power generation,and industrial plants. By competing for the food and habitat of native species, themussels can alter local aquatic ecosystems. They have also affected navigation, fishing, andthe recreational use of beaches.Earlier invaders, such as the lamprey and alewife, continue to affect Great Lakes fisheries.New England waters, such as Long Island Sound, are being invaded by new species on theaverage of one species every 36 months. The most common method of transport is via ballastwater in oceangoing ships; although the organisms also can travel between lakes and riverson boat hulls, on aquatic weeds caught in propellers, on boat trailers, and invisibly in baitbuckets in their larval form. Other aquatic examples of species that have invaded U.S. ecosystemsinclude:Asian clams, which filter the equivalent of the entire volume of northern San FranciscoBay more than once per day, severely disrupting the food chain;hydrilla, an aquatic plant that clogs waterways in 40 states and costs Florida $14million per year to control; andpurple loosestrife, another aquatic plant that has invaded 40 states, where it displacesnative vegetation and disrupts ecosystems.Urban Sprawl: Urban sprawl is a response to individual preferences and market signals.However, it also is the primary cause of numerous social and environmental problems,including the loss of farmland, forests, wetlands, and other natural habitats. Sprawl also iscostly for government because the resulting development usually is served by new roads andsingle-occupant vehicles rather than more efficient transportation modes, such as masstransit, bicycling, or walking.Sprawl is a complex, multidimensional phenomenon, with no easy solutions. There is noconsensus about the severity and breadth of the problem because many of the contributingfactors, such as single-family homes on large lots, low industrial and commercial structures,and abundant parking availability, are considered desirable.5-47