Nitrates are important nutrients that plants and animals depend on for survival. Nitrates appear in water systems in the form of bacteria from chemicals and septic tank leaks. Nitrates are a major ingredient in fertilizer. Nitrates from fertilizer enter the water supply by run off from farm land, gardens, lawns, herbicides and animal feces.
Nitrates are important for water quality because excess amounts increase the growth of algae . Large growths of algae reduce the oxygen level, making the water unsuitible for water animals. Nitrate levels over 10 ppm are dangerous.

Turbitidy is a measure of the cloudiness of the water. Turbidity is measure in nephelometric turbity units (NTU). The more turbid the water, the cloudier the water. It is measured by passing light through the water and seeing how much is reflected off particles in the water. Turbidity increases as a result of suspended soild from clay, silt, plankton, and wastes. These particles flow into the water most often during storms. Murky water cannot support aquatic life such as fish.

Phosphates enter water systems from soils with a high phosphate content, phosphate based detergents, and runoff from farms , gardens, and lawns. Phosphate concentrations are high in waste waters from homes and industries. Most water contains .01 -.05 ppm. Phosphate is an essential element for life, an important nutrient for plants to grow .The number of aquatic plants growing in a particular area is dependent on the amount of phosphate available. In an aquatic ecosystem, inorganic phosphate is rapidly taken up by algae and larger plants, resulting in algae blooms. The algae bloom uses up all the oxygen and impacts water quality.

pH Water contains both H+ [hydrogen] ions and OH- [hydrall ions]. The pH test measures the H+ ions concentration of liquid or subtances. Each measure of the liquid or substance is given a pH value on a scale from 0 to 14.

Pure deionized water contains equal numbers of H+ and OH- ions , and has a p.H . Pure deionized water is considered neutral, neither acidic or base. If the water has more H+ than OH- ions , it is acidic and has a pH less than 7. If the water is too acidic, the fish will experience stress and die. Water with more OH- than H+ ions , is considered basic and has a p.H greater than 7.

Dissolved oxygen is essential for a healthy stream. Although water molecules contain an oxygen atom, the oxygen is not what is needed by aquatic life in water. A small amount of oxygen, up to ten molecules of oxygen per million of water is dissolved in water. Aquatic plants and animals use this oxygen for respiration. Consistently high dissolved oxygen is usually considered optimal. Oxygen can be used up by decomposing material or excessive plant growth due to fertilizers. This is often in the form of an algae bloom. Algae gets fertilized., there is sgrowth., and the oxygen is used up.

Fecal coliform bacteria is naturally present in the human digestive tract, but is rarely found in unpolluted waters. If present, it indicates contamination. Although coliform bacteria in itself is not pathogenic, it occurs with other forms that are dangerous to humans. Contamination may be due to sewage, or septic tank leaks.
Cattle waste has bacteria that may wash into streams and ponds. This may cause pathogens resulting in diseased birds or aquatic animals.

Salinity is the total amount of salt dissolved in water. This determines which plants can tolerate more salt. Salinity in an estuary changes with the tides and season. Rainfall usually reduces salinity. Salinity is measured in parts per thousand (ppt). If you had 1000 cups of water and one cup was filled with salt, that would be 1 ppt salinity.