ABSTRACT
Maintenance of water quality is sought to avoid impacts of pollution on water users. A primary category of impacts are threats to life through transmission of infectious diseases such as cholera. Other impacts include reduced benefits for recreation, diminished health of aquatic ecosystems, and increased treatment costs for other water users. Urban settlements were highly polluted during the Middle Ages, causing epidemics that wiped out entire populations of people and reduced the lifespan of those who survived. Recognition of the linkage between human waste, water supply, and public health did not occur until the 19th century. John Snow’s classic epidemiological study of cholera deaths in London in 1849 identified the Broad Street pump as the source of contamination; removal of the pump handle eliminated the contamination source, and the epidemic subsided. Interestingly, Snow developed a map identifying the residences of the people who contracted the disease as a primary tool to pinpoint the cause of the epidemic (Figure 10.1). This was a clear case of the utility of a GIS-like investigation tool in environmental monitoring. Since that time, efforts to identify, control, and mitigate water pollution have advanced, although somewhat slowly and with varying degrees of commitment by the governing societies.
