Water Quality

The five following parameters are basic to life within aquatic systems. Impairments of these can be observed as impacts to the flora and or fauna with a given water body.
  • Dissolved Oxygen:
  • It is the amount of oxygen dissolved in water. Most aquatic organisms need oxygen to survive and grow.
  • Some species require high DO such as trout and stoneflies. Other species do not require high DO, like catfish, worms and dragonflies.
  • If there is not enough oxygen in the water the following may happen: Death of adults and juveniles, Reduction in growth, Failure of eggs/larvae to survive, Change of species present in a given water body.
  • Temperature: Temperature is a measure of the average energy (kinetic) of water molecules. It is measured on a linear scale of degrees Celsius or degrees Fahrenheit. It is one of the most important water quality parameters. Temperature affects water chemistry and the functions of aquatic organisms. It influences the: amount of oxygen that can be dissolved in water, rate of photosynthesis by algae and other aquatic plants, metabolic rates of organisms, sensitivity of organisms to toxic wastes, parasites and diseases, and timing of reproduction, migration, and aestivation of aquatic organisms.

  • Electrical Conductivity/Salinity:
Salinity is a measure of the amount of salts in the water. Because dissolved ions increase salinity as well as conductivity, the two measures are related. The salts in sea water are primarily sodium chloride (NaCl). They also have a critical influence on aquatic biota, and every kind of organism has a typical salinity range that it can tolerate. Moreover, the ionic composition of the water can be critical. For example, cladocerans (water fleas) are far more sensitive to potassium chloride than sodium chloride at the same concentration. Conductivity will vary with water source: ground water, water drained from agricultural fields, municipal waste water, rainfall. Therefore, conductivity can indicate groundwater seepage or a sewage leak.
  • pH: pH is a measure of how acidic or basic (alkaline) the water is which means strength of the hydrogen). It is defined as the negative log of the hydrogen ion concentration. The pH scale is logarithmic and goes from 0 to 14. For each whole number increase (i.e. 1 to 2) the hydrogen ion concentration decreases tenfold and the water becomes less acidic. As the pH decreases, water becomes more acidic. As water becomes more basic, the pH increases
- Many chemical reactions inside aquatic organisms (cellular metabolism) that are necessary for survival and growth of organisms require a narrow pH range.
- At the extreme ends of the pH scale, (2 or 13) physical damage to gills, exoskeleton, fins, occurs.
- Changes in pH may alter the concentrations of other substances in water to a more toxic form.
  • Turbidity: Turbidity is a measure of the amount of suspended particles in the water. Algae, suspended sediment, and organic matter particles can cloud the water making it more turbid Suspended particles diffuse sunlight and absorb heat. This can increase temperature and reduce light available for algal photosynthesis. If the turbidity is caused by suspended sediment, it can be an indicator of erosion, either natural or manmade.
Suspended sediments can clog the gills of fish. Once the sediment settles, it can foul gravel beds and smother fish eggs and benthic insects. The sediment can also carry pathogens, pollutants and nutrients.
- Non-point source pollution does not come from a specific source.
- Examples of non-point sources of pollution include the following:
  • Point source pollution is defined as “any single identifiable source of pollution from which pollutants are discharged, such as a pipe.”
  • Examples of point sources include:
- discharges from wastewater treatment plants, factories and oil spills;
- operational wastes from industries; and
- combined sewer outfalls.
Non-Point Source Pollution
  • Non-point source pollution does not come from a specific source.
  • Examples of non-point sources of pollution include the following:
  • Sediments from construction, forestry operations and agricultural lands;
  • Bacteria and microorganisms from failing septic systems and pet wastes;
  • Nutrients (from fertilizers and yard debris) and pesticides from agricultural areas, golf courses, athletic fields and residential yards;
  • Oil, grease, antifreeze, and metals washed from roads, parking lots and driveways;
  • Toxic chemicals and cleaners that were not disposed of properly
  • Litter thrown onto streets, sidewalks and beaches, or directly into the water by individuals.
  • Ex: Acid deposition, runoff of chemicals into surface water from croplands, livestock feedlots, logged forests, urban streets, lawns, golf courses and parking lots.

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