Water Quality Report for the Big Sioux River by the Sioux Falls Elementary Gifted Program November 2006

On two sunny but crisp mornings in late September, fifth grade students from the Elementary Gifted Program of the Sioux Falls School District embarked on field trips to the Big Sioux River at two separate locations to conduct water quality tests of the river using several parameters.

The students had prepared for the testing by learning about rivers and riparian areas and the inherent connection between them. They also examined pollution and how it affects rivers, practiced conducting the various tests, examined the intent and process of each test, and explored the value of the river for the people and living creatures of Sioux Falls. An inevitable issue that arose was the impact of humans upon natural areas; and a focus of some of their learning was how we as humans can balance our needs while providing proper respect for natural areas.

Students were divided into two large groups and converged upon the two chosen locations: Falls Park and 57^th and Western Avenue. At each location they were further divided into five stations. The first station was a guided riparian walk along the river; the second station involved using test strips to check for phosphates, nitrates, and pH; at the third station students mixed chemicals with a river sample to determine the level of dissolved oxygen; the fourth station involved searching the river bottom for macro invertebrates; and the fifth station had students taking the temperature of the water and measuring water clarity with a Secchi disk.

Students rotated to each station and results were averaged to get one reading per parameter. The following charts have the results:

 

Falls Park
Pollution Tolerance of Macroinvertebrates	pH	Temp. Differential of 2 sites	Water Clarity	Phosphates	Nitrates	DO
13.5*	8.0	5°	6"	0.25 ppm	0.35 ppm	102% Saturation

57th and Western Ave.
Pollution Tolerance of Macroinvertebrates	pH	Temp. Differential of 2 sites	Water Clarity	Phosphates	Nitrates	DO
16.3*	7.8	5°	6"	0.60 ppm	0.70 ppm	95.8% Saturation

Scoring of the tests was done using Q-values and Water Quality Charts and Indices from the Field Manual for Water Quality Monitoring, by Mark K. Mitchell and William  B. Stapp (7th Edition).  PhD. Students recorded and graphed the results for each of the field tests. A summary of the individual tests follows.

1. The test for macro invertebrates showed there is a decent variety of organisms, and several pollution sensitive organisms living in the Big Sioux River.

 

2. The dissolved oxygen (DO) results were very good. They showed a healthy amount of dissolved oxygen, which means there is a healthy ecosystem capable of sustaining many different aquatic organisms. DO is one of the most important tests that can be conducted on a river.

 

3. The phosphorous levels at Falls Park were very low. The level was higher at the 57^th St. location. Phosphorous is necessary in a river but becomes organic pollution in high amounts. Some potential sources for this are human waste, animal waste, and industrial waste.

    

4. Nitrates are absorbed into a river through sewage and plant and animal decay. A small amount of nitrates is inevitable and necessary in an aquatic ecosystem. The levels we found were small enough to characterize the river as healthy for this parameter.

 

5. The temperature was measured at each location and the difference became the important number. The five-degree difference was a bit high. Aquatic organisms prefer a consistent temperature throughout the river to have the most healthful benefits.

 

6. The turbidity scores we recorded translate to a rather murky and cloudy river. This can be unhealthy, although this is not one of the most significant parameters when calculating the overall health of the river. The Big Sioux has a bottom that is generally muddy, which contributes to its low turbidity score.

 

7. pH levels were pretty good. Acidic levels that are too high or too low can be detrimental to aquatic organisms. Our scores of 8.0 and 7.8 will provide a stable ecosystem for the largest variety of aquatic organisms.

The overall Water Quality Rating was 53.38. The Falls location was 53.19 and the 57^th and Western Ave. location was 53.56. Four years ago the same tests were run and the overall Water Quality Score was 45.32. There were more Macro-Invertebrates that were located four years ago.

The success of the field trip and the profound experience that it provides for our students has us already discussing a return trip to the River in the fall of 2007!

* See Benthic Analysis Instructions for more about the Pollution Tolerance Index