Salado Creek Bacteria Source Tracking

Science Center Objects

The USGS Texas Water Science Center (TXWSC) is collecting surface-water samples from Salado Creek to investigate the concentrations of waste-related constituents and identify their sources (human or other animals) using microbial source tracking. 

Concerns exist that degradation of water quality in the Salado Creek watershed may have an adverse impact on salamander populations that live in and near springs that discharge into the creek, recreational contact, and the quality of life in the Village of Salado. A better understanding of the sources of human/animal waste is needed to properly manage waste in the Village of Salado, which is currently transitioning from on-site sewage facilities (septic tanks) to a municipal wastewater treatment system.

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Salado Creek at Salado, TX (crop)

USGS and Bell County Cooperative Science

Access USGS data for Bell County and learn more about the history of USGS data collection activities in the area.

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Salado Creek near bridge

Salado Creek near bridge   (Public domain.)

The Edwards aquifer, a major aquifer in the south-central part of Texas, is divided into three segments: the large southern San Antonio segment, the central Barton Springs segment, and the Northern segment.  The Northern segment is located in parts of Bell County which has experienced rapid population growth since 2010. Several springs discharge from the Northern segment of the Edwards aquifer in Bell County into Salado Creek near the Village of Salado.

TXWSC and the Bell County Adaptive Management Coalition have been working together on water-quality sampling and studies of surface-water and groundwater sites in the Bell County area since 2012.  Important information has been found in the water-quality data collected by the TXWSC, such as:

  • Higher nitrate concentrations (3-5 mg/L) in samples collected from the Northern segment of the Edwards aquifer (downgradient) compared to nitrate concentrations (1-2 mg/L) in samples collected from the Barton Springs and San Antonio segments of the Edwards aquifer (upgradient).
  • Nitrate isotopes indicated nitrates are from a mixture of fertilizers and human/animal waste.
  • Detections of pesticides (atrazine, CIAT, and/or prometon) in samples collected in 2012 and 2015 from springs discharging into Salado Creek near the Village of Salado.

TXWSC is collecting water-quality samples from 2 sites: upstream from Robertson Spring west of the Village of Salado and downstream from Anderson Spring in the Village of Salado. Two samples will be collected during baseflow and two samples after runoff events. 

The samples will be analyzed for nutrients, bacterial indicators (E. coli), and five microbial source tracking markers. The microbial source tracking markers were selected based on known activities and wildlife in the watershed and include human, ruminant (cattle and deer), swine, canine, and waterfowl markers. Samples for nitrate isotope analysis will be collected, preserved, and archived for future studies.

Wading Salado Creek

Jennifer Wilson and Michael Scheider collecting water quality samples from Salado Creek, TX.    (Public domain)