Page 79 - Water and wastewater engineering

2-22 WATER AND WASTEWATER ENGINEERING

FIGURE 2-7
Land subsidence in the San Joaquin Valley,
16 km southwest of Mendota, CA.
(Source: US Geological Survey Professional
Paper 1401-A, Ground Water in the Central
Valley, California—A Summary Report.
Photo by Dick Ireland, USGS, 1977.)

initial means of extending a fully exploited water source. A half dozen cities, including El Paso,
Texas and Los Angeles, California, are using treated wastewater to recharge potable aquifers.
Los Angeles has been doing so since 1962 (Pinholster, 1995).

2-3 WATER QUALITY
The following four categories are used to describe drinking water quality:

1. Physical: Physical characteristics relate to the quality of water for domestic use. They
include color, turbidity, temperature, and, in particular, taste and odor.
2. Chemical: Chemical characteristics of waters are sometimes evidenced by their observed
reactions, such as the comparative performance of hard and soft waters in laundering.
Most often, differences are not visible. However, in some cases, such as the oxidation of
iron, the reactions result in highly objectionable color.