Water is the common name applied to the liquid form of the hydrogen and oxygen compound H2O. Pure water is an odorless, tasteless, clear liquid. Without freshwater of adequate quantity and quality sustainable development will not be possible. Water pollution threatens development projects and makes water treatment essential in order to main the water quality level. Water quality describes the condition of the water, including chemical, physical, and biological characteristics, usually with respect to its suitability for a particular purpose such as drinking or swimming. In the Florida Keys, good water quality is essential to a healthy marine ecosystem. Environmental water quality, also called ambient water quality, relates to water bodies such as lakes, rivers, and oceans. Water quality standards for surface waters vary significantly due to different environmental conditions, ecosystems, and intended human uses. Toxic substances and high populations of certain microorganisms can present a health hazard for non-drinking purposes such as irrigation, swimming, fishing, rafting, boating, and industrial uses. These conditions may also affect wildlife, which use the water for drinking or as a habitat. Modern water quality laws generally specify protection of fisheries and recreational use and require, as a minimum, retention of current quality standards.