For a complete perspective on overall water quality and description of the freshwater ecosystem, it is important to complete a stream profile. A stream profile contains information on many physical aspects that affect the water quality in a freshwater ecosystem. These factors, which are both in and out of the water, may include stream transects (contour & substrate analysis), temperature, colour, odour, surrounding vegetation, landscape and developments (roadways, buildings, etc.). Each of these factors will be briefly discussed below.
In addition to these factors, an important consideration is to take note of the temperature and weather conditions outside at the time of testing as these may have an important impact on many of the other parameters being investigated in the freshwater study. Note the time of day that testing occurs.
The contour and substrate of the streambed gives a very clear indication of the general physical dynamics of stream flow. Streams in the upper reaches have the highest flow rates and consequently the greatest amount of kinetic energy relative to stream volume. The potential of the water to erode is at its highest. Gravels and sediments are easily carried causing the stream substrate to be well sorted. If the current speed is variable, the substrate will consist of a wide range of gravel sizes and will be poorly sorted. Downstream, the kinetic energy of the stream is reduced. Consequently the stream contour will be less incised and the substrate, consistently, will be poorly sorted. Silts, sands, and muds will be more evident in the lower reaches of the stream.
Note: With safety being of foremost priority, this procedure may not be possible for all freshwater streams.
Stream Transect Contour Map
Water temperature has an effect on water quality. The biological, physical, and chemical aspects of a freshwater ecosystem can be affected by temperature. For example, temperature influences the amount of oxygen that can be dissolved in water , the photosynthetic rate of algae and aquatic plants, the metabolic rate of aquatic organisms and the sensitivity of aquatic organisms to diseases, wastes, and parasites. As stated earlier, water temperature can be influenced by human activity. Soil erosion contributes to an increase in water temperature because of increased turbidity (clarity). Industrial activity often influences water temperature. The addition of relatively warm water to a stream often results in thermal pollution. Dramatic changes in water temperature influence both plant and animal life. Most aquatic organisms have adapted to survive within a range of temperatures. This tolerance range is represented in figure 9 below.
Temperature Tolerance Levels of Aquatic Organisms
The appearance / colour of the water is an important indicator of water quality. The following table explains some of these indicators.
Water Appearance as an Indicator of Water Quality
| WATER APPEARANCE | INDICATES |
| Green | May indicate an overabundance of algae caused by enrichment of the stream. Fertilizer runoff from fields, inadequate sewage treatment, and animal wastes are common causes. |
| Orange/Red | May indicate acid mine drainage, oil well runoff, natural staining due to source headwaters in swamps rich in tannin or iron, or blood from processing plants. |
| Foam | If white and higher than 7-8 cm above water surface, foam is generally caused by detergents. Thinner surface foam may be a mixture of natural oils and soil particles or pollen. |
| Muddy/Cloudy | May indicate erosion and sedimentation in those streams and rivers that are not naturally muddy. Construction sites, dredging activities, activity of bottom feeders like carp, farmland erosion, loggin, and road building are common contributers. |
| Milky/White | May indicate glacial sources of water, pulp and paper mill discharges, or dairy operations |
| Multi-Colour | May indicate oil floating on the surface from human dumping or oil well operations. |
| Dark Reds, Purples, Blues & Blacks | May indicate dyes from leather tanning, printing operations, clothing manufacturing etc. |
The odour of the water is an important indicator of water quality. The following table explains some of these indicators.
Water Odour as an Indicator of Water Quality
| WATER ODOUR | INDICATES |
| Rotten Egg (Sulphur) | Indicates sewage pollution. |
| Musky | Indicates the presence of untreated sewage, livestock waste, or excess algal growth and decay. |
| Harsh/Bitter/Acrid | Indicates industrial wastes. |
| Chlorine | Indicates excessive chorination of waste effluent. |
The landscape surrounding the freshwater also has an important impact on the freshwater quality. The amount of vegetation and slope of the land around the stream effects how much soil erosion occurs and is deposited into the stream. Human activity around the freshwater stream also has an impact on the water quality and should be noted. Is the stream close to industrial buildings, roadways, sewage / drainage pipes, or even public parks? All of these may be sources of pollution that will affect the water quality. Make note in your stream profile of any of these factors and others that you may feel impact on the water quality of the stream.
© 2004 Manitoba Waterways Project
Site Developed by: J. Cook
Questions or comments: Contact the Manitoba Waterways Project
Many files on this site are best viewed with the Adobe Reader.
To download the Adobe reader, visit the Adobe website.