San Antonio River Sediment and Water Quality Monitoring in an Oil and Gas Production Area

Science Center Objects

During 2011-2013, baseline concentrations of many different water and streambed-sediment constituents were determined at Phase I sites upstream from, within, and downstream from the area of active oil and natural-gas production within the San Antonio River Basin.  With baseline conditions previously established, this study will provide current information that couples recent water and stream-bed sediment data with new data on changes in land cover.

The recent surge in oil and gas production throughout the United States, including the Eagle Ford Shale play, has elicited a multitude of concerns about the potential risks to human and environmental health. 

Phase I of the study was carried out in 2011-2013 to establish baseline concentrations of many different water and streambed-sediment constituents at sites upstream from, within, and downstream from the area of active oil and natural-gas production within the San Antonio River Basin.

Phase II of the study will determine if there has been a change in surface water and streambed-sediment quality since collection of Phase I samples at selected monitoring sites and if there is a correlation between PAH concentrations and impervious surface area in the most active area of oil and natural-gas production in the San Antonio River Basin. The following three tasks are associated with Phase II of the study:

Streambed sediment sampling

Manually collecting a streambed sediment sample using a ponar sampler

Task 1

Texas Water Science Center scientists revisted a subset of sites from Phase I (and some new locations) and resampled both water and streambed sediments for a broad range of constituents.  Water and streambed-sediment samples from these sites were analyzed and compared to samples collected in 2011-2013 to determine if there have been changes in baseline conditions.

Task 2

The change in land cover area from well pads, oil and gas-related facilities, roads, storage ponds, and runoff ponds in subwatersheds of the San Antonio River, Cibolo Creek, and Ecleto Creek was estimated in 2008 and 2015 in order to quantify increases associated with oil and gas production during this time period.   

Task 3

Texas Water Science Center scientists collected streambed-sediment samples from upstream and downstream locations within subwatersheds where oil and natural-gas production is most active. Samples were analyzed for polyaromatic hydrocarbon (PAH) concentrations and comparison were made between areas above and areas within the area of active oil and gas production.

Water quality sample examples

Sampling equipment and examples of the sediment sample preparation steps used in this project.