Every day is a great day for water quality testing! Students from Kevin Zerzan’s classes at Gladstone High School visited Rinearson Creek and pond to take a peek at how healthy the waterway is through water quality and macroinvertebrate testing.
In the morning, two classes joined us for macroinvertebrate testing. The first group tested in a very silty section of the pond and found the water quality to be poor; they found a damselfly nymph, scud, water boatmen and aquatic earthworms. The second class tested a different part of the pond and found more sensitive species like stoneflies, mayflies, caddisflies as well as damselfly nymphs, scud, aquatic sowbugs, beetle larvae, snails, water boatmen and aquatic earthworms.
In the afternoon, groups of students tested stream temperature at several points of the waterway and found that it measured 13.15 degrees Celsius in the creek at the waterfall and 18.25 degrees Celsius in the pond. This is a substantial 5.1 degree difference between the two areas, with the cooler water in the flowing creek rather than in the more stagnant pond.
Students also measured the dissovled oxygen, or D.O., of the water’s composition, finding that it measured at 7 mg/L DO with a 67% saturation bove the waterfall and 13.3 mg/L with a 142% saturation in the pond. SO, what does this even mean?
Dissolved oxygen analysis measures the amount of gaseous oxygen (O2) dissolved in an aqueous solution. Oxygen gets into water by diffusion from the surrounding air, by aeration (rapid movement), and as a waste product of photosynthesis.
Total dissolved gas concentrations in water should not exceed 110 percent. Concentrations above this level can be harmful to aquatic life. Fish in waters containing excessive dissolved gases may suffer from “gas bubble disease”; however, this is a very rare occurrence. The bubbles or emboli block the flow of blood through blood vessels causing death.
Adequate dissolved oxygen is necessary for good water quality. Oxygen is a necessary element to all forms of life. Natural stream purification processes require adequate oxygen levels in order to provide for aerobic life forms. As dissolved oxygen levels in water drop below 5.0 mg/l, aquatic life is put under stress. The lower the concentration, the greater the stress. Oxygen levels that remain below 1-2 mg/l for a few hours can result in large fish kills. (from KY Water Watch)
Students also tested the same areas for macroinvertebrates, or insects that indicate stream health. When doing this testing, we use something called the Pollution Tolerance Index which assigns points to different species and determines whether a stream is healthy depending on the sensitivity of the species found.
Most macroinvertebrate tests showed up ‘poor’ or ‘fair’ in regards to water quality with the exception of a few up at the creek that were ‘good’:
Rinearson Creek: Aquatic Sowbugs, Caddisfly larva, Mayflies, Stonefly, Leech, Threadworm, Scuds, Snails, Water Boatman
Rinearson Pond: Water Boatmen, Dragonfly larva, Water Mites, Scuds