1. Water quality.
Water pollution
Basic parameters of water
Inorganig chemicals
Waterborne diseases
Water quality management
Each component of the hydrologic cycle-precipitation, surface water and groundwater
storage, and evaporation-changes the quality of a water body. For example,precipitation in the from
of rain or snow can carry airborne pollutants to the earth’s surface; surface water runoff can cause
erosion and transport sendiment; groundwater recharge can leach chemicals into aquifers; and
evaporation cant elevate concentrations of pollutans in bodies of water by reducing the total volume
of stored water. Each natural component of the hydrologic cycle cant have a negative effect on
surface and groundwater quality.
Humans also have a tremendous effect on water quality. All of us contribute waste to the
environment through the consumption of resources such as food, clothing, housing, and fuel for
transportation. The rapidly growing world population is contributing to the deterioration of our
existing water quality and is creating significant challenges for water managers, industry and fish and
wildlife agencies. This capter will explore problems and solutions that are currently addressed
throughout the world.
Water pollution.
Pollution ( from the latin word pollutus meaning “to soil or defile” ) can occur either naturally. Water
is considered to be polluted if it is unusable for a particular purpose. Natural processes such as
chemical reactions between rocks and water , errosion and sendimentation caused by flowing water,
percolation of survace water into groundwater aquifers, and the residence time of water stored in
rivers, lakes, wetlands, and aquifers, can all create or compund pollution. In some locations, water is
naturally of such poor quality that plants and animals cannot survive.
Unfortunately, humans have caused incredible levels of water pollution. According to the
national water quality inventory: 2000 report to congress, as reported by the U.S environmental
protection agency, only 61 percent of the streams, lakes, and estuaries that were assessed (19
percent of all rivers and streams, and 43 percent of all likes, ponds, and reservoirs in the united
states) met the water quality standards evaluated. Leading pollutants in these impaired waters
included sediments, bacteria, nutrients, and metals (primarily mercury). Runoff from urban areas
and agricultural lands were the primary sources of these pollutants.
The national water quality inventory showed that 78 percent of the state-assessed shoreline
miles of the great lakes were impaired. This classification was given, in part, because of the high level
of pollutants found in fish tissue that could be harmful to human health if eaten. The inventory
made no report on ground-water, but in 1998, it reported to congress that groundwater quality was
generally “good” in the united states (see figure 5.1), meaning that the water quality sampled would

2. support all designated uses. However, measurable negative impacts have been detected from
leaking sources such as underground storage tanks, septic systems, landfills.