Date of Award

Fall 12-11-2025

Degree Type

Thesis

Degree Name

Master of Science - Forestry

Department

Forestry

First Advisor

Matthew McBroom

Second Advisor

Yuhui Weng

Third Advisor

Yanli Zhang

Abstract

The Attoyac Bayou, one of the sub watersheds of Upper Neches River Watershed, failed to attain the water quality standards set by Texas Commission on Environmental Quality (TCEQ) and Environmental Protection Agency (EPA) for elevated Escherichia coli (E. coli) starting with initial assessments in 2000. Therefore, it was listed as impaired on the Texas Integrated Report for Clean Water Sections 303(d) list of impaired water bodies in 2004. In response, Attoyac Bayou Watershed Protection Plan (WPP) was developed in 2014 to address the water quality issue. Best management practices (BMPs) were implemented after WPP was approved by EPA in 2016. The purpose of this study was to analyze the physical, chemical, and biological water quality (WQ) parameters in Attoyac Bayou and its tributaries (Naconiche Creek, Waffelow Creek, Terrapin Creek and Big Iron Ore Creek) between 2010 to 2024 and assess the effectiveness of WPP implemented since 2016. The data from 2010 through August 2023 were retrieved from the TCEQ web reporting tool and the data for recent one year were collected monthly from September 2023 through August 2024. The data were divided into two periods, pre-WPP and post-WPP periods and in four seasons, summer, fall, winter, and spring. The multiway Analysis of Variance (ANOVA) was used to evaluate the differences in WQ parameters in pre-WPP and post-WPP period, and among the seasons too. Water temperature, turbidity, specific conductivity (SPC), dissolved oxygen (DO), pH, nitrate-

nitrogen (NO3-N), nitrite-nitrogen (NO2-N), ammonia-nitrogen (NH3-N), sulfate, chloride, total dissolved solids (TDS), total suspended solids (TSS), and Escherichia coli (E. coli) were analyzed and correlation among these parameters were assessed.

All the water quality parameters except E. coli were within the TCEQ standard in both the periods. DO was higher and nutrients were generally lower during the post-WPP implementation period. However, 56 out of 58 E. coli samples exceeded the TCEQ standard (126 MPN/100 ml) for primary contact recreation during the current sampling period. The higher E. coli concentration was likely from the wildlife sources based on a previous bacterial source tracking (BST) study. The E. coli concentration was significantly higher in the post WPP period and in spring and winter, which can be attributed to higher stream discharges during these periods. The higher mean E. coli concentrations in the post-WPP period at four of the five monitoring sites can also be attributed to the significantly greater stream discharges measured in the post-WPP period. Flow-weighted mean E. coli concentrations were less pronounced between periods indicating that the higher concentrations in the post-WPP period could be due to greater runoff measured in the post-WPP period. This higher stream discharge could indicate that more frequent stream discharge measurements would be needed to better capture variations in streamflow. Additional monitoring and BMP implementation, including wild hog management, are needed to address the elevated E. coli concentrations in these streams.

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Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

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