| The Storm
Drain Detectives are conducting six water quality tests each month to monitor the storm
drain run-off. The tests are:
Dissolved Oxygen
Water Temperature
Electrical Conductivity
pH
Turbidity
Nitrates
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| Dissolved
Oxygen (D.O.)
>This is the amount of oxygen dissolved in the water.
>D.O. is important because aquatic organisms need oxygen
to survive and grow. Too much or too little D.O. can be
dangerous to the river ecosystem. For example, for water to
support cold water fish, such as trout or salmon, the D.O. level
should not fall below 6.0 to 8.0 mg/L.
>D.O. levels can increase and decrease when dead organic
matter, sewage, yard waste, and oil and grease enter the river.
>D.O. data is collected using two different
instruments, the CheMet kit, which samples water removed from
river in sampling can, and the D.O. meter, which actually
dangles a probe into the river to sample the ambient water. Only
the D.O. meter's probe data is posted on this web-site.
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CheMet Kit-
Manual D.O. color scale. |
Digital D.O. meter - probe
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Water
Temperature
>This is a measure of the average kinetic energy of water molecules. The faster or slower water molecules
move increases and decreases the temperature respectively.
>Temperature is important because it affects water
chemistry and functions of aquatic life. It influences the
rate of plant photosynthesis, metabolic rates
of organisms, sensitivity of organisms to waste and pollution,
and the reproduction and migration of river
animals, especially fish.
>Temperature can change with the removal of vegetation
around and in the river, soil erosion, storm water run
off, and alterations to the river’s flow.
>Water temperature is also measured using a digital probe. It
is this information, taken from digital probes, that is posted
on this website.
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Digital thermometer (also
D.O. meter). |
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TDS/
Electrical Conductivity
>TDS (Total Dissolved Solids) is the amount of
dissolved solids (i.e. salts) in the water. TDS can be
measured indirectly by measuring the electrical conductivity.
The more dissolved salts in the water, the more electricity the
water will conduct.
>Electrical conductivity is the ability of the water to
conduct an electrical current.
>Conductivity is important because it directly effects the
quality of the water used for drinking and irrigation.
Because conductivity measurements are based on the ionic
composition of the water, many organisms
can be hurt or helped by a small imbalance of these ions.
>Conductivity will vary depending on the source of the
water. Tap water, which in Lodi is pumped from groundwater
aquifers, has naturally occurring TDS up to
400 mg/ L.
>Conductivity will also vary with the source of run-off,
whether it be rainfall, water drained from agricultural fields,
or waste water drainage. This means conductivity can indicate
ground water seepage or a sewage leak.
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Electrical conductivity probe. |
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| pH
>This is a measure of how acidic or basic the water is.
These measurements identify the hydrogen ion concentration.
This concentration is translated into a pH scale that ranges
from 0 to 14 and reveals the hydrogen
ion levels in the water. A pH level of 7 is neutral. A level
between 0 and 7 is acidic, and a level between
7 and 14 is basic.
>pH is important because many chemical reactions inside
aquatic organisms depend on a very narrow, specific
pH range. pH changes may also alter the concentrations of other
substances in the water so they become
toxic.
>pH changes can come from the input of manmade and natural
acidic or basic substances from run off that flows
into the river.
>The pH in the water collected from the river is tested using
two different protocols. The first test is done using
a pH test strip paper, followed by a second test with pH
probe meter. Only the pH meter's data is posted of this
web-site.
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pH paper. |
pH probe. |
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| Turbidity
>Turbidity is a measure of the amount of suspended
particles in the water. Algae, suspended sediment, and organic
matter in the water increase turbidity to unhealthy levels for
certain organisms.
>Turbidity is important because a high level of suspended
particles in the river can diffuse sunlight and absorb
heat, which increases temperature and reduces the light
available for plants. High levels of suspended
sediments can also clog fish gills and smother fish eggs.
>Turbidity increases with bank erosion, excessive algal
growth, and changes in the river’s flow.
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Digital turbidity meter.
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Nitrates (NO-3) >Nitrogen is an
element needed by all plants and animals to build protein.
In aquatic ecosystems, nitrogen is naturally present in many
forms.
>Urban and farming run-off to the river can
significantly increase nitrates levels in the water.
Sewage can also be a source of nitrates if added by humans to the
river. Nitrates can be an indication of high levels of
fertilizers, animal waste, or other run-off contamination.
>A color wheel nitrate test kit is used.
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Nitrates meter |
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