Water pollution refers to the introduction of foreign substances to a water source that is either toxic to life forms within the water, or which creates excessive oxygen demands, thus depriving indigenous life forms of necessary oxygen.
Regular Websites
Association of State and Interstate Water Pollution Control Administrators
The ASIWPCA is a national professional organization consisting of state, interstate, and territorial officials responsible for the implementation of surface water protection programs throughout the United States. An overview of the organization is available, along with meeting notices, policy statements, and task force program areas. - Association of State and Interstate Water Pollution Control Administrators
http://www.asiwpca.org/
As part of the National Academy of Science, educational material relating to water quality in the natural environment, water pollution, and related topics can be found here, including drinking water basics and safe water for developing nations. - NAS Water Information Center
http://dels.nas.edu/water/pollution.php
Although published in the United Kingdom, this guide to water pollution will be applicable to anyone anywhere, at least to a large extent. The various types of water pollution are described, and the causes, dangers, steps to prevention, and treatment of polluted water are discussed. - Water Pollution Guide
http://www.water-pollution.org.uk/