Hogans Creek Watershed Project
Due to the Covid-19 pandemic, this study was cut short. However, we were able to collect and analyze 42 total water samples from seven different dates during the spring semester.
- After the 24 hour period, students used hand-lenses to count the bacteria colonies on the plate. Per the instructions/interpretation guide of the Petrifilm, students counted "dots" on the plate that had associated gas bubbles, which indicated a colony of live bacteria. A dot without an associated gas bubble was assumed to be nonliving particulate matter or other contaminate.
- Two different counts of "bubbled dots" were counted for each Petrifilm plate:
- Blue dots with associated bubbles = E. coli bacteria colonies
- Red dots with associated bubbles = Other coliform bacteria colonies
- These two counts were then added to determine the total coliform colony count.
- Each plate was counted at least three times by different lab group members to ensure the count was correct.
- Once the count was complete, Petrifilm plates were disposed of in a bleach solution.
- Below are a few examples of the counted plates.