Water quality refers to the physical, chemical and biological characteristics of water. We evaluate water quality from the standpoints of whether water is safe to drink, safe to come in contact with, and for ecosystem health. A general perception of water quality monitoring is that it tells us whether water is polluted or not. In fact, water quality is a very complex subject, in part because water is a complex medium. It is intrinsically tied to the ecology of the Earth. Industrial pollution is a major cause of water pollution, as are runoff from agricultural areas, urban storm water, and discharge of untreated sewage.

The U. S. Environmental Protection Agency is responsible for protecting public health by ensuring safe drinking water and protecting ground water. It provides information about safety of public drinking water, standards of safety, quality of local drinking water, and other useful information through maps and other resources.

The National Sustainable Agriculture Information Service is managed by the National Center for Appropriate Technology (NCAT) and is funded under a grant from the United States Department of Agriculture's Rural Business-Cooperative Service. It provides useful information about water quality, drought, conservation, and soil moisture management through documents and presentations.

The U. S. Department of Agriculture's National Agricultural Library is also a good source of information on water quality. Their web site provides access to a wide variety of resources.

The American Society of Mechanical Engineers convened the First Water Quality, Drought, Human Health & Engineering Conference in October 2006 at Las Vegas, Nevada. The conference papers are a useful resource.

The U.S. Department of Agriculture's Natural Resources Conservation Service provides information, data, software, and support contacts.