Investigating the causes of reduced dissolved oxygen concentrations in Kickapoo Creek, TX

Authors: Kannan, Narayanan; VENKATARAMAN, KARTIK - Tarleton State University; STROEBEL, JEFF - Tarleton State University; TAYLOR, LEAH - Texas Institute For Applied Environmental Research

Submitted to: Environmental Monitoring and Assessment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/21/2022
Publication Date: 7/8/2022
Citation: Kannan, N., Venkataraman, K., Stroebel, J., Taylor, L. 2022. Investigating the causes of reduced dissolved oxygen concentrations in Kickapoo Creek, TX. Environmental Monitoring and Assessment. 194:574. https://doi.org/10.1007/s10661-022-10209-2.
DOI: https://doi.org/10.1007/s10661-022-10209-2

Interpretive Summary: Excessive pollutants can reduce DO concentrations in river water. In the most recent Texas Integrated Report for Surface Water Quality, the Texas Commission for Environmental Quality (TCEQ) classified the Kickapoo Creek in Henderson County, Texas as impaired because it failed to meet the stipulated DO criteria for streams.Therefore, the low DO issue of the Kickapoo Creek in was investigated. Instantaneous and continuous DO data were analyzed and related to various water quality variables (such as different forms of nitrogen, phosphorus and oxygen demand of flowing water) to identify causes of low DO. Sophisticated statistical and graphical analysis were performed on the DO and water quality data. The study found progressively decreasing DO trends from the origin of the river (upstream) to the end (downsteram) and low DO in summer months. These trends can be related to various pollutant sources occurring in the watershed, the low water flow of the river in summer months and the increase in daily summer temperatures occurring in the watershed. The findings will help to design strategies to reduce the pollutants reaching the Kickapoo Creek and improve the DO status of the river.

Technical Abstract: Excessive organic matter and nutrients can depress dissolved oxygen concentration (DOC) in streams. The aim of this study was to understand the depressed DOC of Kickapoo Creek in Texas, USA which is an impaired stream, identify the possible sources causing the depressed DOC and elevated bacteria levels, and to identify possible remedial measures. Monthly grab water quality data was monitored for nine stations in the watershed. For three of the nine stations 24-hour DOC was also monitored for a comparison with the minimum and average DOC criteria. Correlational, graphical, spatial, and temporal analyses were carried out for DOC concentration with other water quality variables which have a potential to depress DOC in the stream. The correlational analyses show weak to moderate correlation for DOC with nutrient and oxygen-demanding substances present in the stream. There are spatial and temporal trends in DOC data that can be attributed to the nutrient influx into the stream. A pattern of increasing nutrient concentrations from upstream to downstream partially explains the decreasing Dissolved Oxygen (DO) concentrations observed in the lower reaches. Visual interpretations of riparian vegetation and sediment influx also support the spatial patterns in DO concentrations. Majority of the depressed DOC occurs in the summer months when streamflow is at a minimum. The depressed DOC during summer is partially explained by the increasing daily temperatures for summer months as revealed by the trend analysis of the daily temperature data from 1981-2020 using modified Mann-Kendall test, Pettitt test and Sen’s slope. Keywords: Kickapoo Creek, stream characterization, chlorophyll-a, contact recreation, aquatic life use, modified Mann-Kendall test, water temperature.