Water Quality Standards

Mrs. Ashley

Carbon dioxide: Added to water by respiration of plants and animals in water, microbial decomposition of dead animals. Makes water a weak acid and increases the ability of water to pick up materials that are slightly alkaline. In areas that are forested and have fallen leaves, as the fallen leaves decompose, a weak acid is formed and this then takes the alkaline materials from the soil called leeching.

Carbon dioxide is needed for photosynthesis and it is water is used to create the organic compounds of growing plants

pH: Rain water may be between 5.6-6.0 When slightly acid rain water reacts to soils and minerals that are slightly alkaline it may become 8.0 -8.5. Naturally occurring water ranges from 5.0 to 8.5. Decomposition of organic matter in water increases the carbon dioxide content and reduces the pH of water. Fish cannot take up oxygen as rapidly in low pH waters containing carbon dioxide as in high pH waters with low carbon dioxide. Acceptable pH for drinking water is 6.5 -8.5. Natural sea water has a pH of 8.1. Fish grow best in the 6-9 range.

Dissolved Oxygen: Polluted water is usually low in oxygen. Slightly acidic water that contains oxygen will be corrosive to pipes. Oxygen is more soluble in cold water. Fish are more active in warm water and therefore require more oxygen. Organic matter consumes oxygen less rapidly in cold water than in warm water. Oxygen shortages cause changes in the bacteria causing decomposition. Eventually if all oxygen is missing as happens in a very eutrophic lake at the deep layers, methane forming bacteria pull oxygen from the carbon dioxide and water to produce methane and hydrogen in the organic rich muds at the bottom of the lake. Low oxygen amounts result in many of the bacteria that normally use oxygen will first extract it from Nitrite, then Nitrate, and then sulfate. Release of nitrogen gas and hydrogen sulfide will occur (rotten egg odor). Levels for warm water fish should not be less than 0.4 ppm and for cold water fish not less than 0.5 ppm

Biochemical Oxygen Demand: Water is kept in a closed container and the concentration of oxygen that is lost to the container due to the decomposition of organic matter . Clean water looses less than 0.5mL of oxygen per Liter of water.

Ammonium nitrogen: Clean waters rarely contain more than 0.1 ppm.N. Community sewage usually contains 15 t0 50 ppm N. Ammonia is rapidly oxidized in natural water to nitrate and nitrite, so if ammonia is present in high concentrations, it means that pollution is recent. High ammonia levels kill fish and lower levels may produce excess growth of algae. Presence of ammonia is a sign of sanitary pollution.

Phosphorous (Phosphates): This is an important nutrient for aquatic plants. Agricultural runoff and pollution from waste water sources causes excess concentrations. The excess concentrations causes increase in algae and weeks, as the excess dies, oxygen is used up by bacteria in the lake drops in oxygen and fish die. This process is called eutrophication. There may be an increase in algae scum, and hydrogen sulfide gas may be produced.

Water Hardness: Calcium and Magnesium ions comprise hardness. Calcium sulfate and magnesium sulfate contribute to the hardness of water. Hardness should be above 50 to 300 ppm in lakes and streams.

EPA Drinking Water Quality Standards (do not exceed these amounts) :

Flouride 2.0 ppm

Iron 0.3 ppm

Manganese 0.05 ppm

Chloride 250.0 ppm

Nitrate 10.0 ppm

Sulfate 250.0 ppm

Foaming Agents 0.5 ppm

Total of all dissolved solids 500.0 ppm