Austin, TX is the 12th most populous city in the USA with a population density of 1,161 people/km2 (3,097 people/mi2). Like many urban creeks, Austin’s creeks often have elevated levels of fecal indicator bacteria (FIB). High FIB levels can cause disease outbreaks, but depending on the source, may also indicate the presence of other toxic contaminants. Molecular Source Tracking (MST) can identify source species of FIB, which in urban creeks are typically domesticated dogs and humans. We used dog and human-associated molecular markers to monitor 8 creeks in Austin, TX from 2017 to 2025. The human-associated marker was detected in about ¾ of the study samples while the dog-associated marker was detected in about ⅕ of the samples. We also found significant day to day variation in FIB, indicating that the FIB sources are not consistent. So while dog feces accounts for some of the FIB found in Austin’s creeks, human FIB are much more prevalent. The pervasiveness of human FIB suggest that efforts to reduce FIB contamination are complex and that the risk of disease exposure to humans may need to be reassessed. We are continuing work to determine the sources of the human FIB.