Water Quality
Quality water in a stream or river is indicative of a healthy stream with lots of aquatic activity. As you take a closer look with a microscope at a water sample from the river, you can see how healthy the stream is by the number of species you have caught. Identifying them is one of the tests.
Turbidity is a measure of water clarity and another one of the tests. Unhealthy water can be murky, but sometimes natural substances, not pollution, can cause the murky water. A turbidity test measures the amount of suspended particles in the water. More of these free floating particles, algae or other materials, cause greater turbidity resulting in less light penetration through the water. Less light inhibits photosynthesis, necessary for aquatic plant growth and production of dissolved oxygen.
Dissolved oxygen is necessary for both aquatic plants and animals to survive and a very valuable part of the test. Oxygen is a clear colorless, odorless gas that dissolves in water. Although only small amounts of it are dissolved in the water, they are important amounts. These amounts are supplied by diffusion of atmospheric (air) oxygen into the water and by the projection of oxygen from photosynthesis by aquatic plants. Lack of dissolved oxygen can cause aquatic animals (e.g., fish, macroinvertebrates) to quickly leave the area or face death.
The suspended particles in the water absorb heat, which warms the water. Warmer water holds less dissolved oxygen than cold water. also, the faster the stream flows, the more energy it has and the more sediment it can carry. Dissolved oxygen levels are reduced by excessive amounts of organic matter, such as sewage, manure, or leaves that wash into the stream. Warm water released from industrial outlets, flowages, or storm sewers can also reduce dissolved oxygen levels.
Information presented here was taken from UW extension study guides. If you would like more information about the testing process or would like to become more involved in this important testing project, email watchdogviews@watershedwatchers.org