Let’s begin by looking at the color of the water. Water color can be affected by soils, clay, plant and animal matter, algae, and microorganisms such as bacteria. If the water is brown and cloudy, it is most likely a soil erosion problem. If the water is green, it is most likely caused by algae. Be sure to make a note if you see algae, especially globs of bright green, slimy looking algae on the surface of the water. Look closely at the surface of the water to see if there is an oily sheen or oily rainbow colors (similar to what you see running off a parking lot in a rainstorm). Clear water is most desirable, but be aware that clear water does not mean the water is clean. Some of the worst polluting chemicals do not change the color of the water. It is also important to remember that not all bodies of water will be naturally clear, even if there is no pollution at all. Many streams and rivers in Kansas are naturally turbid (cloudy due to sediment particles suspended in the water – you may think of this as a “muddy” look), and many native Kansas species such as catfish and sturgeon are adapted to “muddy” streams. If you have a muddy stream, be sure to make a note on your field sheet whether you think it is due to non-point source pollution (lots of crops and fields around) or if you think it is natural.
There is more information about non-point source pollution on the Friends of the Kaw website, and we will talk about this type of pollution throughout our lessons.
Observe the water in the stream, and record your observations on the field sheet. Then gather a sample in your clear container to more closely examine the color of the water. Note if there is any silt or sediment settling out of the water on the bottom of the container.
Ideally, you should record your observations at the site. However if you choose to wait until you are back in the laboratory to observe the color of your sample, be sure to gently shake the container to mix up the sample so it appears as it did naturally.
Keep in mind that water systems change constantly, and it may not be the same color tomorrow, or even in a few hours. You may wish to take multiple samples from the same site over a period of time for comparison.
On your field sheet, rate your water quality according to the scale below.
Record the color and rating on the data sheet.
Next we will consider the odor at the sample site. Odor, like color, is a qualitative measurement, instead of quantitative. This means our result is an observation (for example, on a scale from poor to good) instead of a numeric measurement (for example, ounces or inches).
Most samples may not have a distinguishable odor. However, some may have a detectable smell that can tell you information about pollution sources that may be present. The human nose is very sensitive at detecting many different odors, even in small concentrations.
First, observe and record the smells in the air at the water-sampling site. Then you may collect a sample in your jar and secure the lid. Once you are back in your classroom or another place where there is no detectable odor, you may open the jar and note the smell.
Swirl the water gently in the container and sniff. If you detect a strong smell, do not put your nose close to the container opening. Instead, use your hand to move air across the open container towards your nose (we refer to this as wafting). If you are dealing with a sample that may contain bacteria such as E.coli, be careful to not splash it on your face.
The sample may smell fishy or like algae, or it may smell like manure if livestock or wildlife have been in the stream or pond recently. Smells that may be described as fishy, soil-like, or musky are most likely natural smells. You may pick up non-natural smells, such as chlorine (similar to a chlorinated swimming pool), sulfide (smells like rotten eggs), sewage, manure, or chemicals.Record the odor of the sample on the field sheet. Also note if there is an absence of smell. Record ranking (qualitative) data on the data sheet using the chart below. Later, you can evaluate whether the odor relates to the other data you have recorded.
A feature that many people notice about rivers and lakes is the presence of foam. Foam can be pillowy or look like suds, brown or cream-colored or white, and smell grassy or soapy. The appearance of foam will indicate whether it is natural or the result of pollution.
Foam often results from the natural process of decomposition. Autumn leaves, fish, plants, and other aquatic life that has died decomposes in the water, releasing fatty acids and oils. These compounds are similar to the foaming agents in soaps and detergents. When water is agitated by wind or by the natural flow of the river or stream, these foaming agents create bubbles. You may see natural foam on a windswept lake or near the bank of a fast flowing stream. Foam appears more often at certain times of year, such as fall, after trees lose their leaves, or spring, after trees and flowers lose their buds. When temperatures rise, the process of decay occurs more rapidly, increasing the release of the fatty acids and other organic substances. This natural foam is white, brown or cream-colored, and smells earthy or grassy. It is usually more “pillowy” than “sudsy.”
Certain types of pollution, such as detergents containing phosphorus can create foam or bubbles. This foam is usually white, sudsy, and may smell like soap or perfume. If this type of foam is present, it is important to determine the source of the pollution so that it can be resolved.
Observe and record the presence or absence of foam. Be sure to write down a detailed description of the location, appearance, and the smell if possible. It may not be possible to get close enough to determine the smell, or it may not be advisable to get your nose close to the water if the site seems heavily polluted. Always use your best judgment!
From your notes describing the foam, determine some characteristics of the water. For example, decide whether you think the foam indicates a small or large amount of decaying organic material. Where do you think the organic material is coming from (for example, are there a lot of deciduous trees hanging over the water? Do you see crop rows falling into the water?) Maybe it indicates the presence of detergents or other pollution (look around – it may be possible to follow a stream of suds back to a pipe or other point source).