Boulder investigates possible sewer leak near University Hill
Targeted stormwater testing found limited evidence of sewer leakage and potential human markers in one area; city staff are assessing whether a repair may be needed.
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Boulder stormwater staff are investigating potential human markers in one University Hill area after targeted testing found limited evidence of sanitary-sewer leakage into the stormwater system.
At an Oct. 19 Water Resources Advisory Board meeting, city staff described targeted sampling at potential trouble spots selected using sewer-pipe condition assessments and inspection video. They tested stormwater for Escherichia coli (E. coli), an indicator of fecal contamination, and used microbial source tracking to look for a genetic marker specific to humans.
Staff said they were investigating the potential markers to determine whether a sewer repair might be needed. The sampling focused on a sewer shed at the bottom of the Broadway network, associated with one of the city’s largest stormwater outfalls.
Staff said E. coli can signal the presence of pathogens, but the presentation did not connect this investigation to any health effects. They also said sources of E. coli across Boulder Creek can be dispersed, so the targeted sewer investigation does not explain creekwide levels. The targeted work is expected to continue into 2027.