BioSITE staff train high school students to carefully collect and test water samples from the river then use results to help determine the health of the stream. The high school students then mentor fourth graders in performing water quality tests, recording data, and interpreting results throughout the year.
Measures the amount of oxygen available in the water. Fish, plants, and invertebrates all need oxygen to survive. Oxygen enters water from the air and is produced by aquatic plants. Dissolved oxygen levels less than 4 ppm (parts per million) are stressful to organisms and 6 to 11 ppm are optimal for most fish.
Measures how acidic or basic water is. Water below 7 is acidic, while over 7 is basic. Most organisms thrive in the 6.5-8.5 range.
Causes of pH change:
Rate of Flow
Measures how fast the water is flowing. Fast moving water has more oxygen and is usually cooler than slow moving water. If water flows too quickly over a long period, animals and plants can be swept downstream. Rate of flow is affected by the slope and composition of the bank, dams, in-stream obstacles, rainfall, and curviness of the river’s path.
Measures how deep the center of the river is. Water levels change depending on rainfall and obstructions. Water is higher during the rainy season and lower during the dry season. Humans can also affect river height by damming rivers. Dammed rivers may be lower than usual downstream but flooded above the dam. Dams periodically release water which can also cause sudden flooding.
High temperatures increase plant growth and bacterial growth, decrease the amount of oxygen in the water, and cause organisms to become more sensitive to pollutants and diseases. Unusual changes in temperature can trigger plants and animals to deviate from their normal cycles by migrating, mating, or hatching at the wrong time.
Factors that affect temperature:
Total Dissolved Solids
Total Dissolved Solids measures how many tiny particles of minerals and metals are in the water. Too few or too many minerals can be unhealthy for plants and animals. Increased pollution and runoff can increase total dissolved solids.
Turbidity measures the clarity of the water. Cloudy water is caused by suspended particles like soil, plant matter, and small organisms. Turbid water can result from erosion, urban run-off, and disturbance of bottom sediment. Water with abnormally high turbidity can damage fish gills and lead to the suffocation of fish eggs and small aquatic insects.
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