Official website for the National Water Program. Water is the common element that links ecosystems. It links forest ecosystems of the interior mountains with the bays and estuaries along the coasts. It transports food, nutrients and other biologically important materials and organisms. It dilutes, moves and removes wastes; it cools organisms and the land, maintaining the climactic conditions that support and sustain life. Finally, water supplies energy to ecosystems because, through cooling and its motion, water saves energy that organisms and ecosystems would otherwise need to expend.