Recently Keep Coyote Creek Beautiful partnered with the students of Yerba Buena High School to conduct a series of water quality tests on the section of Coyote Creek nearest to their school. As part of that project their teacher Dr. Rosemarie Calma had them write about their experience. Below we have the write up of Kevin, Rey, Kyle, Kiet, and Christian.
Rivers have always been an asset to the ecosystem. It provides a home for aquatic creatures, food for predators, and water for all species. However, when pollution occurs, many rivers end up unusable and uninhabitable for the native species, causing a collapse in the whole ecosystem. This is exactly what is going on with Coyote Creek, a massive 64-mile long river in Santa Clara County that is home to thousands of species. Pollution, as well as urban expansion, has been the main cause of its slow decline and many species are forced to migrate away. Two hundred years ago, this river was a vast and colorful haven flowing through the Coyote Valley.
This situation is the driving force behind our experiment. My peers (Rey, Kyle, Kiet, and Christian) and I were interested in learning more about Coyote Creek. On February 18th of 2022, my peers and I started our journey with the help of our advisor, Dr. Calma, and Keep Coyote Creek Beautiful coordinator, Colter Cook. With the help of Mr. Cook, we were able to gain access to some of the creek’s water samples and start the experiment, which consisted of water quality checks including turbidity, dissolved oxygen, saturation, salinity, and pH levels.
First off was turbidity, which is basically the clearness of the water. For this, we just had to see how clear a certain symbol (the Secchi disk sticker) inside the creek water was. If the sticker was fuzzy in any way, we would have to give it a turbidity of 40 or 80 depending on the severity of the fuzziness and if we could see the symbol clearly, then it would be 0. For us, we saw the symbol clearly, so we gave it a 0 JTU [Jackson Turbidity Units].
Left: Rey extracts samples from the water (amazing)
Right: Turbidity test with Secchi disk sticker
Up next was dissolved oxygen and pH levels, which involved taking the water samples and putting a test tablet in to make the water change colors. For this section, we had six different tubes for the water (three for oxygen and three for pH), meaning that we had to do these experiments three times each to get an average at the end. The color would then be used to give us a corresponding value.
For the dissolved oxygen, the water turned into a light shade of pink in two of the tubes, but the last one stayed clear, which corresponded to an average value of 2.667 parts per million (ppm).
For the pH level, the water turned into a mixture of lime and dark green, resulting in an average pH level of 7.33. This means that the Coyote Creek water was neutral and not acidic, making it safe for wildlife still.
Afterward, we checked its salinity level. We did this by using a refractometer three different times and got an average afterwards. The three tests, however, all resulted in a salinity level of 0 parts per thousand (ppt), meaning the samples we had had no salt molecules in it.
Rey and Kyle testing salinity with refractometer
Far Right: view through refractometer
Lastly, we checked its saturation level by using a chart as a guide. The chart gives us the saturation level with regards to the sample’s temperature and oxygen levels. Since our samples were 12 degrees Celsius and had an oxygen level of mainly 4 ppm, the saturation level was 40%.
“For a quick and easy determination of the percent saturation value for dissolved oxygen at a given temperature, use the saturation chart below. Pair up the mg/l of dissolved oxygen you measured and the temperature of the water in degrees C. Draw a straight line between the water temperature and the mg/l of dissolved oxygen. The percent saturation is the value where the line intercepts the saturation scale. Streams with a saturation value of 90% or above are considered healthy.”
Overall, the experiment was a blast, and I think that we learned a lot from this experience from our research of the topic beforehand due to interest and from our monitoring activity. We learned that the creek was in a bad condition, but from our experiment, we understood that it wasn’t as bad as it seemed. It was still uninhabitable for most fish due to the low oxygen levels and saturation levels, but it wasn’t as bad as we thought it would be. Lastly, I want to thank our advisor Dr. Calma and Mr. Cook for providing us with the materials. It was a great experience for all of us!
Made possible by donations by City of San Jose ESD and EarthEcho.
Written by Kevin, Rey, Kyle, Kiet, and Christian of YBHS
Edited by Colter Cook