Air
and Water Temperature
Water temperature is one of the most important water quality
parameters and has direct effects on water chemistry and the
functions of aquatic organisms. Temperature influences the
dissolved oxygen content of the water; the rate of photosynthesis
by algae and other aquatic plants; the metabolic rates of
organisms; the sensitivity of organisms to toxic wastes, parasites
and diseases; and the timing of reproduction, migration and
aestivation of aquatic organisms. Factors which can affect
temperature include sunlight energy, seasonal and daily changes,
shade, air temperature, stream flow, water depth, inflow of
groundwater or surface water, and the color and turbidity
(cloudiness) of the water. Other factors include soil erosion,
storm water runoff, and alterations to stream morphology,
substrate and flow. In the Firelands region, the water quality
objective is that the water be less than 35 degrees Celsius.
pH
pH is a measure of how acidic or basic (alkaline) the water
is. As the pH decreases, water becomes more acidic and as
the pH increases, water becomes more basic. At the extreme
ends of the pH scale, (2 or 13) physical damage to gills,
exoskeleton, and fins occurs. Changes in pH may also alter
the concentrations of other substances in water to a more
toxic form. In fresh water, increasing temperature decreases
pH. Because limestone is common in our area are water has
a pH range between 7.3 and 8.8.
Dissolved
Oxygen
Dissolved oxygen (DO) refers to the amount of oxygen dissolved
in water. The dissolved oxygen concentration in water can
directly affect reproduction, incubation, changes in species,
and death of adult and juvenile fish and other organisms.
Factors which affect the dissolved oxygen concentration in
water include temperature, DO sources such as photosynthesis,
DO sinks such as respiration and breakdown of organic material,
and salinity. Low dissolved oxygen levels usually result from
algal blooms, human waste and animal waste. When DO drops
below 4mg/L the water column no longer has enough oxygen to
support most aquatic life which may result in fish kills.
Conductivity
Conductivity is a measure of the ability of the water to conduct
an electrical current. This ability is affected by the nutrients
and minerals in the water as well as various pollutants. Generally,
the conductivity of rivers in the United States ranges from
50-1500 u³S/cm and inland fresh water studies indicate a range
between 150 to 500 u³S/cm for supporting good mixed fisheries
(EPA 2003). Local geology can also affect conductivity. In
our area we have limestone bedrock found on the western side
of the Firelands and shale and sandstone to the east. Dissolved
limestone in the water column due to groundwater influences
in the stream increase the conductivity of the water naturally.
Turbidity
Turbidity is a measure of the amount of suspended particles
in the water. Watersheds in general have a natural turbidity
level with inputs from natural erosion, organic decay and
algae. Turbidity can be an indicator of erosion, excessive
nutrient loading and algal growth. Because of the number of
suspended plants and animals (plankton) found within stream
systems, turbid water can also be considered natural. The
level of turbidity will vary from stream to stream depending
on the nutrient loading, geology and stream dynamics. Local
streams in the Firelands area become very turbid (coffee like
appearance) after storms due to agricultural run-off and streambank
erosion caused by urban development.
Nitrates
Nitrate is a nutrient that occurs naturally in water bodies
and promotes aquatic plant growth. Excessive nutrient levels
can lead to algal and aquatic weed growth that in turn depletes
the available oxygen in the water column. Runoff containing
detergents, fertilizers, animal waste, industrial waste, or
sewage, contributes to elevated nutrient levels as does excess
dumping of vegetative material. High levels of nutrients can
cause hypoxia and eutrophication in water. When nitrates reach
higher levels than 3mg/L, the result may be hypoxia (extreme
loss of dissolved oxygen) and eutrophication (excessive aquatic
plant growth in response to high levels of nutrients).
Ammonia
Nitrogen
Ammonia is excreted by animals and produced during decomposition
of plants and animals. Its natural breakdown thus returns
nitrogen to the aquatic system. It is rapidly oxidized in
natural water systems by special bacterial groups that produce
the ions of nitrite (NO2), nitrate (NO3), and ammonia nitrogen
(NH3–N), which are then used by plants; therefore ammonia
is an additional source of nitrogen as a nutrient which may
contribute to the expanded growth of undesirable algae and
other forms of plant growth that overload the natural system
and cause eutrophication. The un-ionized form of ammonia (NH3)
is the preferred nitrogen-containing nutrient for plant growth
and is also one of the most important pollutants because it
is relatively common, but can be toxic to animals, causing
lower reproduction and growth, or death to fish and other
aquatic life. The water quality objective, according to the
U.S. EPA, is less than .025 mg/L. Concentrations of ammonia
(NH3) should not exceed .05 mg/L to ensure that sensitive
aquatic organisms are not harmed.
Orthophosphate
(Soluble Reactive Phosphorus)
Many forms of phosphate exist in the water, but only orthophosphate
is readily taken up by the algae and aquatic plants. It is
also the only form that is easily measured. Phosphate is a
nutrient that is not found in large quantities in streams.
As a result, modest increases in it can lead to large changes
in the stream conditions. Some effects of phosphates are:
accelerated plant growth, algae blooms, low dissolved oxygen,
and the death of certain fish, invertebrates, and other aquatic
animals. Human sources of phosphate are: “wastewater
treatment plants, runoff from fertilized lawns and cropland,
failing septic systems, runoff from animal manure storage
areas, disturbed land areas, drained wetlands, water treatment,
and commercial cleaning preparations.” (Source: U.S.
EPA) There is no formal water quality objective for Orthophosphate,
but the level for total phosphorus (Recommended by the US
EPA, 1986) is less than 0.10 mg/L for streams that do not
empty into reservoirs.
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