Escherichia coli concentrations in Fremont River tributaries at Capitol Reef National Park, 2008–2017

Hackbarth, Carolyn; Weissinger, Rebecca

This report summarizes Escherichia coli (E. coli) concentrations in water samples collected in tributaries of the Fremont River at Capitol Reef National Park between July 2008 and September 2017. E. coli is a fecal indicator bacteria found in waste from humans, livestock, and wildlife. High concentrations of E. coli bacteria can indicate a public health hazard. The Utah Division of Water Quality (UDWQ) has developed acceptable concentrations as part of the state’s water-quality standards. In 2014, a segment of the Fremont River, including the portion flowing through Capitol Reef National Park, was listed as impaired for E. coli, water temperature, and total dissolved solids. UDWQ prioritized developing a plan to reduce E. coli concentrations in the Fremont River. As part of this plan, water samples have been collected at numerous locations along the impaired segment of the Fremont River to test for E. coli concentrations. Along with efforts by UDWQ, the National Park Service Northern Colorado Plateau Network has monitored three tributaries to the Fremont River within Capitol Reef National Park since July 2008. This sampling is part of a long-term monitoring program that includes E. coli as part of a suite of water-quality parameters that have been reported elsewhere (e.g., Hackbarth and Weissinger 2016; Hackbarth and Weissinger 2013). Samples are collected monthly on a rotating schedule at two locations in Sulphur Creek and one location each in Pleasant Creek and Oak Creek. At all four water-quality sites within the park, E. coli concentrations have exceeded both chronic and acute state water-quality standards for recreational use. Relationships between E. coli, streamflow, and turbidity were examined to determine if there were patterns that contributed to E. coli exceedances. At all three streams, high E. coli concentrations were found even during conditions of low flow and low turbidity, suggesting that E. coli contamination is not just due to flood events. Most exceedances occurred during the state-defined recreation season of May 1–October 31. This timeframe encompasses over 75% of the park’s annual visitation and also corresponds to cattle trailing through Oak and Pleasant creeks and dispersed livestock grazing on public lands upstream of the park in all three watersheds. Paired samples taken upstream and downstream of a popular hiking area and the park developed area on Sulphur Creek showed similar patterns in E. coli concentrations, suggesting that in Sulphur Creek, most E. coli contamination enters upstream of the park, rather than coming from park visitation or infrastructure. Upstream and downstream comparisons are not available for Oak Creek and Pleasant Creek, which have less park infrastructure and visitation than Sulphur Creek. Results from this effort can help inform park managers of potential problems with E. coli contamination within the park and assist the State of Utah in determining potential sources of E. coli contamination in the Fremont River.

Escherichia coli concentrations in Fremont River tributaries at Capitol Reef National Park, 2008–2017

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