Environmental Engineering Reference
In-Depth Information
TAble 10.1
Total Residual
l Chlorine (TRC)
Level (mg/L)
Effect
0.06
Toxic to striped bass larvae
0.31
Toxic to white perch larvae
0.5 to 1.0
Typical drinking water residual
1.0 to 3.0
Recommended for swimming pools
• Introduced pollutants, such as pesticides, metals, and oil
• Constituents found naturally in water that can nevertheless be
affected by human sources, such as dissolved oxygen, bacteria, and
nutrients
The magnitude of the effects of these constituents is influenced by proper-
ties such as pH and temperature; for example, temperature influences the
quantity of dissolved oxygen that water is able to contain, and pH affects the
toxicity of ammonia.
The second factor to be considered is that the only valid way to answer
this question is to conduct tests, the results of which must then be compared
to some form of water quality standards. If simply assigning a “good” and
“bad” value to each test factor were possible, the meters and measuring
devices in water quality test kits would be much easier to make and use.
Instead of fine graduations, they could simply have a “good” zone and a
“bad” zone.
When you get right down to it,
water quality
—the difference between good
and bad water—must be interpreted according to the intended use of the
water. For example, the same perfect balance of water chemistry that pro-
vides a sparkling clear, sanitary swimming pool would not be acceptable
for drinking water and would be a deadly environment for many biota (see
Table 10.1
). In another example, widely different levels of fecal coliform bac-
teria are considered to be acceptable—depending on the intended use of the
water.
State and local water quality practitioners as well as volunteers have been
monitoring water quality conditions for many years. In fact, until the past
decade or so (until biological monitoring protocols were developed and
began to take hold), water quality monitoring was generally considered the
primary way to identify water pollution problems. Today, professional water
quality practitioners and volunteer program coordinators alike are moving
toward approaches that combine chemical, physical, and biological monitor-
ing methods to achieve the best picture of water quality conditions. Water
quality monitoring can be used for many purposes:
