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Crooked Creek Chemistry (FBCEC)

TopicLaboratory and Hands-on Activities - General
Water quality is important. Participants will chemically test the water condition of a section of Crooked Creek to give them a picture of the stream’s health. Note: This lesson is most meaningful when combined with physical stream measurements and biological sampling.
Grade Level7 - 12
Recommended SettingCrooked Creek
LocationFred Berry Conservation Education Center, Yellville, AR

Education Program Coordinator, 870-449-3484

Duration1 - 2 hours
Suggested Number of ParticipantsUp to 15
Special Conditions
Water conditions and weather permitting
  • Measure the stream’s chemical conditions using Hach test kits, as used by AGFC stream teams.
  • Record and analyze chemical data to determine the quality of the stream.
  • Explore possible reasons for any surprising results.
  • Become aware of AGFC’s stream team program and how to get involved.
Key Terms*

Dissolved oxygen


pH scale


Stream Teams

Total dissolved solids



Chemical data sheets/pencils

Distilled water (for “blanks”)

Hach test kit and manual

Waste container (plastic, wide mouth)

The chemical parameters can be measured to determine the stream’s quality. Water quality test kits vary but typically measure pH, dissolved oxygen and nitrate and phosphorus levels. Other measurements include turbidity and total dissolved solids. Water samples can be measured accurately if collected properly, and with biological and physical data, the story is  more complete.
  1. Choose a sampling site on Crooked Creek. This may depend upon creek conditions at the time.
  2. Find a safe location (out of foot traffic and bright sunlight) to place the thermometer for measuring air temperature. Record the temperature on the data sheet after a few minutes. (Glass thermometers are not recommended because they are fragile.) Measure the water temperature in a safe location as well and record results on the data sheet.
  3. Collect water samples and perform the following tests as described in the Hach manual: (Use a sample bottle with distilled water for the “blanks.”)
    • Nitrate, high range (cadmium reduction method), page 215
    • Dissolved oxygen, high range (HRDO method), page 323
    • Phosphorus, reactive (PhosVer 3 – ascorbic acid method), page 345
    • Turbidity (absorptometric method), page 429
    • Readings should be taken with the pH and total dissolved solids meters. Record results.
  4. Additional tests may be performed as time allows.
  5. Wrap up with discussion of results and whether they were expected or surprising. Pose some hypothetical questions. What could cause turbidity to be high or dissolved oxygen to be low?
  6. Provide information about AGFC’s stream team program.
  • What natural or man-induced factors can affect nitrate levels in a body of water?
  • What is the relationship between temperature and dissolved oxygen? What other factors influence dissolved oxygen?
  • How might low dissolved oxygen levels affect the organisms in a body of water?
  • What are some possible sources for an elevated phosphorus level in water?\
  • What is turbidity and what factors affect it?
  • Arkansas Stream Team. Arkansas Game and Fish Commission.
  • http://www.agfc.com/fishing/special-programs-fish/stream-team.aspx
  • Dobson, Clive and Gilpin Beck, Gregor (1999). Watersheds – A Practical Handbook for Healthy Water. Firefly Books, Ltd., Buffalo, NY.
  • Murdoch, Tom, Cheo, Martha with O’Laughlin, Kate (2001). Streamkeeper’s Field Guide – Watershed Inventory and Stream Monitoring Methods. Adopt-A-Stream Foundation.
  • Pex, Deborah Rodney (1994). What Is A Watershed? America’s Clean Water Foundation, Washington, D.C., and Association of State and Interstate Water Pollution Control Administrators.
  • Watershed Protection – an activity book. Project WET International Foundation, 2003.
  • www.projectwet.org; info@projectwet.org

Dissolved oxygen – amount of oxygen in fresh water such as a stream or freshwater lake

Nitrate – a salt or ester of nitric acid

pH scale – measure of a liquid’s or solid’s alkalinity, represented on a scale of 0 to 14 with 7 being a neutral state, 0 the most acidic and 14 the most alkaline

Stream Teams – Arkansas Game and Fish Commission education program in which concerned citizens can be involved in stream and watershed conservation through education, stewardship and advocacy

Total dissolved solids – concentration of all substances contained in water which has been filtered through a sieve size of two micrometers; solids remaining after evaporation of a water sample

Turbidity – degree to which water looses transparency due to suspended particles