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. 

Our Methods

  • In the morning, a water sample was taken from Hogans Creek.  The specific location is at the corner of 8th Street and Jefferson St., where the creek first emerges from underground below the UF Health Medical campus.  This location is about a block away from our school campus.  
  • The sample was taken using a Swing Sampler.  This was a swinging plastic collection bottle, attached to a 12 foot long pole.  This allowed us to stand at the sidewalk above the creek and sample the water directly without having to leave the pavement.  
  • Once back in the lab at school, the water was split into 18 different containers, one for each of the 18 lab groups that would be conducting tests throughout the day.
  • During their class period, lab groups used testing strips to test the levels of nitrates and nitrites.
  • Then would then take a 1 mL sample and place it on a Petrifilm plate.
  • One the Petrifilm plate was prepared, it was placed in the incubator for 24 hours.
  • 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.