Youth water quality tests – Part 1 – Temperature

Teach students about science by playing in the river! You can learn about the health of a river by studying the temperature of the water and how it changes.

This is the first article in a series by Michigan State University Extension about testing water quality with students.  By conducting some simple tests, students can learn about how clean or polluted nearby streams are.  By doing further investigation, the students can identify the problem and help to improve the river. There is an international program called GREEN (Global Rivers Environmental Education Network) which began in the spring of 1984 with a group of concerned students at a high school located along the polluted Huron River in Ann Arbor, Michigan.  Their teacher contacted Dr. William Stapp at the University of Michigan, and together they developed a comprehensive educational program called GREEN. These articles discuss the water quality tests conducted as part of GREEN.


Water temperature influences many systems in the watershed including the amount of oxygen that can be dissolved in the water, the sensitivity of animals to pollution, parasites and diseases.  Some animals can only live in cool water, like trout. One of the ways that humans can raise water temperature is by factories adding warm water to a river or lake.  Another source may be runoff from warm streets, roofs and parking lots.  Another source of temperature increases may be soil erosion.  Soil erosion raises water temperatures because the dirt in the water makes it darker making it heats up more.  Stream shading also affects water temperature; a tree lined stream will be cooler than one with no shaded areas. 

A coldwater fishery has a temperature range of less than 70 degrees Fahrenheit.  Most trout prefer a coldwater fishery.

A coolwater fishery has a temperature range of 65-75 F.  Walleye and perch prefer a coolwater fishery.

A warmwater fishery has a temperature range of greater than 75 F.  Bass and bluegill prefer a warmwater fishery.

The Test

This is one of the simplest tests to conduct, and most people already have the equipment for it.  Use a simple weather thermometer to test the water or any thermometer with a range of -5 to 150 F. Next, take another reading a mile upstream from the site.  Ideally there should be no more than a five degree difference between the two sites.

When you take the temperature, try to get the middle of the stream.  Not too close to the top, bottom or sides of the stream.  This will give you a more accurate reading.

Looking at the data and what kids can do to make it better

If there is a temperature change of more than five degrees between the two locations, the students can make guesses about what caused the temperature change and what they can do about it.  Possible explanations include:

  1. Lack of stream shading – Students can work with a local watershed group or conservation district to plant trees along the edge of the stream and cool down the water.
  2. Runoff from the road, parking lot or roof – Do roadside ditches or parking lot drains go into the river?  Does water run off the edge of a parking lot or a roof downspout quickly to the river?  If so, creating a buffer or rain garden to slow down the water before it enters the stream can help cool things down.
  3. Thermal pollution from a commercial, industrial or agricultural source – Occasionally, a business might be discharging warm water directly to a stream.  This process is regulated to protect our waters, but the regulators and enforcers can’t be everywhere at once.  If you suspect that this is happening, call 1-800-292-4706 to report the incident.
  4. A smaller stream enters the creek bringing water of different temperature – You can use the above measures on the smaller stream.

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