During this portion of the trip the teachers will be doing water quality testing. Although it would be better to test water quality above and below drainage points, this is simply not possible on this trip. We will be testing below a drainage point.
| Temperature
Most aquatic organisms are ectothermic requiring that the the temperature of the water remains consistent. Water temperature also influences the amount of dissolved oxygen. The higher the temperature the less soluble oxygen is which makes the oxygen less available for aquatic species. The state of Alabama requires the water temperature of lakes and streams used for public water supply not to exceed 90 degrees Fahrenheit. |
| pH
pH describes how acidic or basic a water supply is. pH ranges from 0 which is very acidic to 14 which is very basic. The EPA requires a pH range for a river to be between 5-9. The buffering capacity of the Cahaba is quite high due to the large amount of limestone and chalk found in the areas it flows through. pH is not usually a problem in the Cahaba. |
| Turbidity
Turbidity refers to the clarity of the water. Turbidity is influenced by the amount of suspended solids in the water. Clear water is not only important for safe recreational use, it is also influences the ability for aquatic organism to survive. If water has too many suspended solids the growth rate of fish is reduced and the ability for eggs to survive is decreased. Very turbid water also decreases the light penetrating ability and decreases primary productivity. Changes in primary productivity disrupt the food chains making less food available for all organisms. |
| Dissolved oxygen
Dissolved Oxygen (DO) is a necessity for aquatic organisms. Low amounts of DO usually indicate poor water quality. The amount of DO can be decreased during times of drought. Moving water helps keep DO values higher by allowing mixing a atmospheric oxygen into the water. A river can have too much DO as well. This may be result from increased amounts of photosynthesis which sometimes occurs when nutrients such as fertilizers are added to a river by runoff. 15% of the land area covered by the Cahaba is made up of pastures and crops. The state standard value for DO is 5 mg/L. Low DO values are most common is the summer months. |
| Phosphates
Phosphates are required for the growth of plants and animals. Excessive phosphates can allow for plants to grow out of control and cause eutrophication to occur. Phosphates are added to rivers by runoff from crops and urban areas. The typical concentration of phosphates in the Cahaba is between .5-1 mg/L which exceeds the amount recommended by the EPA. |
| Total Dissolved Solids
Water is an excellent solvent which means that materials readily are dissolved in it and can allow for impurities to accumulate. The amount of dissolved solids is related to water hardness. Some dissolved solids found in rivers are heavy metals which are toxic to organisms even in low concentrations. Other dissolved solids are calcium, potassium, chloride, nitrate and fluoride. Water with high amounts of dissolved solids usually have high conductivity. |
| Hardness
Hardness of water is rated by the amount of calcium carbonate found in a body of water. The main ions that contribute to water hardness are magnesium, calcium, and manganese. Water is considered to be soft when it has a concentration of calcium carbonate between 0-75 mg/L and water is considered to be hard when the concentration of calcium carbonate is higher than 300 mg/L. Hard water allows for metal ions to precipitate out and makes these metals unavailable to aquatic life. The average value for hardness in the Cahaba is 74 mg/L. These means that heavy metals such as lead and zinc do not precipitate out. These heavy metals can collect in fish tissue making the fish undesirable and toxic to eat. |