Water Quality Testing
The health of a stream can be measured using many different techniques. Scientists look at the physical and chemical condition of the water as well as the presence and health of the critters that reside there. They use instruments like Secchi disks, probes, nets gauges and meters to determine how healthy the water is. Water samples are taken from the middle of lakes and the smallest of streams. Scientists observe what's happening along the stream banks to see if it has an impact on the water quality. They collect all sorts of things including fish, plants, dirt, and bugs, all of which can tell the scientists about the quality of the stream.
Temperature:
Scientists use temperature to determine what kind of animals can survive. If the temperature gets too hot or cold for some organisms, they die. Temperature also affects the chemical makeup of the water. For example, warm water contains less oxygen than cold water. A healthy stream bank full of trees and vegetation can help keep stream temperatures cool for trout and other fish.
Dissolved Oxygen:
Just like us, fish and other aquatic organisms need oxygen to breath. A high level of dissolved oxygen in the water is an indicator of a healthy stream although some areas, like swamps, have naturally low levels of DO. Lots of factors affect how much DO is in the water. These include temperature, the amount and speed of flowing water, the number of plants and algae, and pollution. The composition of the stream bottom can also affect the level of DO. Gravelly or rocky bottoms stir up more water than muddy ones do and create bubbles, putting more oxygen in the water.
pH:
The p stands for "potential of" and the H is hydrogen. pH levels range from very acidic (0) to very basic (14). Most waters range from 6.5 to 8.5 and are considered "neutral". High levels of pH can be deadly to fish and other aquatic organisms.
Nutrients:
Everyone needs nutrients to survive. However, sometimes you can have too much of a good thing. too many nutrients can hurt aquatic organisms by causing algae blooms, or fast growing algae that absorbs needed oxygen from the water. The main nutrients scientists are concerned with are phosphorous and nitrogen. Nutrients are found in residential and agriculture fertilizers, pet waste, waste-water treatment plants, sewage plants, and other sources.
Toxic Substances:
Scientists also determine the health of a stream by testing for things like oils, metals, and pesticides. Vehicle traffic, maintenance and fueling, leaks and spills, and manufacturing processes all contribute to our polluted waterways. Heavy metals are also considered toxic substances. These include copper, lead, zinc, arsenic, chromium and cadmium and are typically found in urban stormwater runoff. Metals come from automobiles, paints, preservatives, motor oil and household and industrial chemicals.
Turbidity:
Turbidity refers to the clarity of the water. To determine the turbidity, scientists measure how many particulates (little bits of stuff) are floating around. If you can see the bottom of the pond from the dock, the water has low turbidity. If you can't see your hand a foot under water, the water has high turbidity. Turbidity is often the result of erosion and high nutrient levels.
Bacteria:
Scientists sample for certain types of bacteria that are found in the stomachs and intestines of warm-blooded animals and humans. Although this type of bacteria is not necessarily harmful, it can indicate the presence of pathogenic (disease-causing) bacteria, viruses, and protozoans. Wastewater treatment plants, on-site septic systems, domestic and wild animal manure, and stormwater runoff are all sources of fecal bacteria.
