Temperature is a critical water quality and
environmental parameter because it governs the kinds and types of aquatic life,
regulates the maximum dissolved oxygen concentration of the water, and
influences the rate of chemical and biological reactions. The organisms within
the ecosystem have preferred temperature regimes that change as a function of
season, organism age or life stage, and other environmental factors. With
respect to chemical and biological reactions, the higher the water temperature
the higher the rate of chemical and metabolic reactions.
Seasonal variations in stream temperature may be caused by changing air
temperature, solar angle, meteorological events, and a number of physical
aspects related to the stream and watershed. These physical features include
stream origin, velocity, vegetation types and coverage, stream configuration,
land-use, and percentage of impervious area. For example, a narrow, deep
well-shaded shoreline reduces the impact of warming by the sun; whereas, a wide
shallow stream would be more impacted by solar heating.
In a warm water streams, the temperatures should not exceed 89 degrees
Cold water streams should not exceed 68 degrees (Fahrenheit). Often summer heat
can cause fish kills in ponds because high temperatures reduce available oxygen
in the water.
Temperature (Water Quality Index Calculator)
Based On Temperature Change from a Reference Site
At the control site place the thermometer about 0.5 inches from the bottom
or a few inches below the water surface. Keep the thermometer in the
water until a constant reading is attained (approximately two
minutes). These try to collect temperature in a portion of the stream
that is shaded.
Record your measurement in Celsius. (To convert from Fahrenheit to
Celsius, subtract 32 and multiply by 5/9.)
Repeat the test temperature at your test site.
Subtract the upstream temperature from the reference site from the temperature downstream and record the result as temperature change (C).
Try to collect temperature data under similar conditions and using the same
thermometer- thermometer should be readable to 0.1 C.
from the graph.