Determining The Health of a Stream/River

Stream Discharge - is the total amount (volume) of water flowing in the stream. It is important to know how much water is flowing in a stream because it affects many things about a stream, for example: * Salmon need slower flowing areas of a stream to lay their eggs. * Other aquatic animals (like macroinvertebrates) and algae can’t live in a stream that has water moving too fast.

Stream Discharge – how to measure Stream discharge is measured by multiplying the area of the stream by its velocity. Stream discharge is measured in cubic feet per second (cfs). Visualize cutting a stream like I’m cutting this banana to understand what a cross-section is. You measure the area of a stream at a cross-section slice of the stream. cfs (cubic foot per second) – visualize a box 1 foot by 1 foot by 1 foot filled with water; that’s a cubic foot of water.

Water Quality Parameters Dissolved Oxygen Oxygen in the water comes from the air/ atmosphere and the aquatic plants (through photosynthesis). All plants (terrestrial and aquatic) make their food through the process of photosynthesis; one of the by-products of photosynthesis is oxygen.

Water Quality Parameters Dissolved Oxygen Aquatic organisms – plants and animals – need to breathe oxygen, just like people. Caddis fly larvae and aquatic plants on a stream bed.

Water Quality Parameters Dissolved Oxygen Dissolved oxygen levels change throughout the day based on water temperature and photosynthetic activity. The gold line is dissolved oxygen (DO). See how it forms a 24-hour cycle with the highest DO levels during the summer typically occurring during the late afternoon/ early evening. This is because the aquatic plants have been photosynthesizing all day putting oxygen into the water. After the sun goes down, the plants go into respiration where oxygen is taken from the water and CO2 is given off as a by-product. The graph shows a 24-hour clock; 21:00 equals 9pm

Water Quality Parameters Temperature Stream temperature controls how plants and animals live. Warm water contains less dissolved oxygen than cool water. Plants and animals have different ranges of temperatures that they prefer to live in. Some can only live in cool water while others can live either in warm or cool water.

Water Quality Parameters Temperature Young salmon need temperatures of around 9°Centigrade; adult salmon need water that’s 12°Centigrade. An easy way to calculate Fahrenheit from Centigrade is to double the Centigrade and add 30. For example, 9 degrees Centigrade is 9 X 2 plus 30 = 48 degrees Fahrenheit.

Water Quality Parameters pH A pH measurement tells us whether a stream is acidic or alkaline. pH values range from 0 to 14; values from 0 to 7 are considered acidic, 7 is neutral and above 7 is considered alkaline or basic. The pH of a stream is determined by what kind of rocks the stream flows over and sometimes by humans. In Washington, the pH of water on the west side of the mountains tends to be either neutral or slightly acidic. On the east side of the mountains, the water tends to be more basic or alkaline. This is because the rocks and geology is so different on the west side versus the east side. Human caused changes in pH can come from failing septic systems or stormwater or other types of pollution.

Water Quality Parameters Nutrients Nitrate is one of the nutrients which is used as food by plants . Nitrates can come from decomposing plants and animals, human sewage, fertilizers and stormwater run-off. Excessive amounts of nitrates can cause too much algae growth. This lowers the dissolved oxygen levels when the algae die and decompose. Nutrients are another name for food. Plants use oxygen in the decomposition process. Low oxygen levels are bad in a stream because it can cause fish and other animals to die.

Water Quality Parameters Turbidity Turbidity is a measurement of how clear or cloudy the water looks. Water becomes cloudy when it contains solid material. This solid material can be a combination of sediment, algae, aquatic animals - anything that can be suspended in the water. Turbidity can affect the ability of fish to live by clogging their gills. Turbidity is a measurement of the scattered light in a water sample (the light that bounces off of any solid material in the water sample).

Water Quality Parameters Bacteria Not all bacteria are harmful to humans but some are, like fecal coliform. These “bad” bacteria produce toxins which make people sick. It is important to protect humans from these harmful bacteria which could occur both in our drinking water as well as in the lakes and rivers where people play and have fun. Bad bacteria, like fecal coliform, come from the intestines of warm blooded animals and are spread to people by contact with the feces of dogs, birds, and other humans.

What can you do to help a stream? Collect data as part of a student monitoring team. Don’t litter! Educate other people about how important streams are to people and animals. Educate yourself about how streams work and what makes a stream healthy. Give a presentation to local officials (city and county officials) about the stream you monitor. These are the people who make decisions that affect the health of streams. If you have an on-site septic system at your house, make sure it is operating properly. Pick up your pet waste. Other ideas???