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Tuesday, August 22, 2017

Watershed Protection Planning: Bacteria

Double Bayou East Fork

SELECT model used to estimate pollutant loadings from bacteria for the Double Bayou Watershed.

Photo By: Stephanie Glenn, HARC

Written by Stephanie Glenn, Program Director, Hydrology and Watersheds

This is the third article in a series on Watershed Protection Plans; to read the others see Texas Watershed Protection Planning and Watershed Protection Planning in Galveston Bay.

The previous articles discussed the ways in which watershed protection planning restores and protects water quality in the Houston-Galveston Region. Watershed protection plans are guidance documents developed by watershed stakeholders detailing voluntary management measures that restore and protect water quality. One of the projects highlighted was the Double Bayou Watershed Protection Plan, an effort in which HARC coordinated with local stakeholders to develop a watershed protection plan for the Double Bayou Watershed in Liberty and Chambers counties, on the Eastern shore of Galveston Bay.

A critical indicator of nonpoint and point source pollution in water is bacteria; specifically, the fecal indicator bacteria E. coli (freshwater) and Enterococci (tidal water). These bacteria are used to indicate risk from fecal contamination and associated pathogens in waterbodies. Bacteria are found in fecal wastes of all warm-blooded animals, so possible sources are things that produce fecal matter, such as humans, livestock, and wildlife. Waterways are considered impaired for contact recreation if bacteria levels are too high; ingesting this water can cause severe gastrointestinal distress. Bacteria are the biggest pollutant in Texas waters.

The Double Bayou Watershed Protection Plan project monitored bacteria in the waterways to determine bacteria loads and set goals to reduce loads through voluntary management measures. The SELECT (Spatially Explicit Load Enrichment Calculation Tool) model was used to estimate potential pollutant loadings from bacteria and spatially characterize critical loading areas across the Double Bayou Watershed. SELECT was developed by the Department of Biological and Agricultural Engineering and the Spatial Science Laboratory at Texas A&M University. For this project, the distribution of livestock, wildlife, wastewater treatment facilities and septic systems along with the contributions from each were quantified through source-specific bacterial production rates. The results from the SELECT analysis and water quality monitoring provided stakeholders insight when they determined the appropriate voluntary management strategies to reduce bacteria loads in their watershed. HARC researchers Dr. Stephanie Glenn, Ryan Bare and Brad Neish recently had a paper published in the Texas Water Journal detailing the SELECT analysis for the Double Bayou Watershed. To read “Modeling bacterial load scenarios in a Texas coastal watershed to support decision-making for improving water quality”, see the Volume 8 No 1 issue of the Texas Water Journal.