Name:__________________________

The river tank at the front of my room is called Salix Creek (at least by me) in honor of my dog, Salix Rocky Lund Lovrien.  Is the water in the tank clean water?  Below are a few scientific tests that will help answer this question.  In this classroom lab, we will conduct each test and you are to record your results.

Test 1. Dissolved Oxygen.    

For a body of water to sustain living fish, it must have adequate dissolved oxygen.  What factors increase the amount of dissolved oxygen in a stream such as Splitrock Creek?  The major factors are exposure to air (when it tumbles over a rapids, the amount of dissolved oxygen increases), plants and algae (they add oxygen when they get sunlight), and cool temperatures.  What factors decrease the amount of dissolved oxygen?  Organisms such as animals use dissolved oxygen, dead plants remove oxygen as they are being decomposed, dirty water blocks sunlight and therefore decreases the amount of photosynthesis, and warm water holds less dissolved oxygen (just like a warm soda is often flat).

How much dissolved oxygen is needed in a creek?  Below 4 ppm, the oxygen levels are so low that many fish are at risk of dying.  Some fish, such as trout, require at least 9 ppm and thrive at levels of 12-14 ppm.  We will test the levels of dissolved oxygen in the water and then, considering the water's temperature, records its % saturation.  If the % saturation is low, this is an indication that the water is unhealthy and oxygen is being removed from the body of water.

Water Quality Index:  110% - 85% saturation=Good, 85% -70% =Fair, 70% and lower = Poor water quality.

*What is the level of DO (in ppm) in Salix Creek?____________________________

Test 2. pH Balance

In most bodies of water, pH should be near neutral.  Acid rain, spills and contamination often result in alterations of pH of natural bodies of water.

Water Quality Index: pH of 6.5 to 7.5 Good, 6-6.5 or7.5-8.0 Fair, below 6 or above 8 Poor.

Test 3.  Turbidity

Science loves to use fancy terms to describe simple concepts.  If you look at a Splitrock Creek, you would probably describe it as 'cloudy' or 'stained.'  A fancy word to describe how cloudy water appears is turbidity.  It is natural for water around here to have some color, due to plankton that serves as the base of the food pyramid.  However, deeply stained water may indicate exessive algae growth, high levels of erosion and/or unstable riverbanks. 

Water Quality Index: NTUs 0-20 Good, 20-50 Fair, 50 - 100 Poor

Test 4.  Total Dissolved Solids

If you fill a glass with Brandon water, it appears clear.  Yet we know that it is "hard" water, meaning it is loaded with dissolved solids.  In nature, there is no source of pure water that is completely lacking in dissolved solids.  But water sources near habited areas are often extremely high in dissolved solids as we flush detergents, fertilizers, and other chemicals down our drains (or they reach rivers by means of the runoff from our yards) and this water ends up in local waterways.  So while a water sample should have some dissolved solids, high levels often indicate excessive runoff from human activities.  

Water Quality Index:   0-225 mg/L= Good,  225 - 350 mg/L= Fair, 350 and high=  Poor

*What is the level of dissolved solids in Salix Creek?____________________________

The smallest forms of life are bacteria. These organisms are too small to be seen by the naked eye but they are widely distributed. Some bacteria are beneficial while others can cause serious illness. We will test our water source for total bacteria and coliform bacteria. Almost all natural water will have bacteria growing in it so we will expect to have some bacterial colonies on our total bacterial count. An extremely high bacterial count will indicate a good chance that some of the bacteria will be disease-causing. Coliform bacteria are found in the guts of warm-blooded animals and don’t belong in natural water sources. The presence of coliform bacteria indicates that raw sewage or farm animals are polluting the water.

Total bacteria count: 0-99 Good, 100-115 Fair, 116 – Poor

Coliform count: 0 Good, 1 Fair (don’t Drink), Above 1 Poor (no swimming)

PRELAB Questions: (answer the following questions – use complete sentences! Follow the six traits writing rubric.)

    Dissolved Oxygen:

pH:

Turbidity:

Total Dissolved Solids:

Coliform bacteria:

2. Splitrock Creek runs through McHardy Park in Brandon, SD. We will be testing the quality of the creek water within this park. From the park, numerous features of the Brandon landscape can be seen that might impact water quality.

a. Explain three things about this "suburban" environment that might pose a threat to the creek.