Buck Creek Watershed Protection Plan Development

Watershed Protection Plan Development Project

The seasonal dynamics in fecal bacteria populations in Buck Creek can be the result of a number of landscape utilization processes associated with human habitation, agricultural activities, herbivore and avian guild landscape utilization patterns and cattle landscape utilization patterns. A proactive watershed management plan for mitigating fecal bacteria impairment will be developed and based on understanding and then altering the timing, frequency and duration of fecal bacteria loading activities within the riparian zone immediately adjacent to Buck Creek. Currently there is not a geospatial inventory of the landscape components in this watershed. Furthermore, there is an information vacuum as to the spatial and temporal distribution of potential sources of fecal bacteria loading. In the Watershed Protection Plan Development for Buck Creek Study we will examine landscape utilization patterns and their potential role in Buck Creek's E. coli impairment and evaluate subsequent mitigation strategies.

The Watershed Protection Plan Development for Buck Creek project will basically pick up where the Bacterial Monitoring for the Buck Creek Watershed project (TSSWCB Project #03-7) left off. The TSSWCB, Texas AgriLife Research, TWRI, Hall-Childress SWCD, Donley SWCD, Salt Fork SWCD, Red River Authority (RRA) and Texas AgriLife Extension Service will work together to (1) identify the specific sources of the bacteria, (2) evaluate alternatives for restoring the waterbody, and (3) develop a watershed protection plan to restore the waterbody through a stakeholder driven process.

Identification of Sources

This project will include review and evaluation of existing data and information pertaining to bacterial contributions and sources to Buck Creek. New data, of known and specified quality, will be collected and analyzed to differentiate and quantify the relative contributions of bovine livestock and other human and animal bacteria sources into Buck Creek. This assessment and differentiation between bacteria sources will utilize, and be coordinated with, the bacterial source tracking (BST) and will be compared with the Texas E. coli source library generated by Texas AgriLife Research in El Paso which now contains almost 2,000 E. coli isolates from over 1,500 different domestic sewage and animal fecal samples. The library contains diverse E. coli isolates which were selected after screening over 4,400 isolates by genetic fingerprinting to exclude identical isolates from the same sample and include isolates with unique genetic fingerprints. This project will provide sufficient documentation of the data and technical analyses conducted that will aid the project staff in communicating the assessment results to watershed stakeholders, TSSWCB, TCEQ, and U.S. EPA, as necessary.

Livestock and wildlife fecal samples, along with septic system samples will be obtained from a variety of sources in the watershed. Sources will be identified through a sanitary survey to be conducted by Texas AgriLife Research in Vernon. An inventory of existing land use patterns in the Buck Creek watershed will be conducted utilizing available imagery and aerial observation. The locations of bridges, springs and human habitation will be ground-truthed to ensure high quality data.

The BST tasks for this project will be conducted in two phases. The first phase involves assessment and monthly targeted grab sampling of creek segments at greatest risk for fecal pollution loading for a period of six months. It will include analysis of water samples for E. coli as previously performed by Texas AgriLife Research in Vernon using USEPA Method 1603 {USEPA, 2002 #612} and Enterococcus bacteria using a modification of USEPA Method 1600 and mEI medium {USEPA, 1997 #765}. A polymerase chain reaction (PCR) genetic test for the E. faecium human-specific enterococcal surface protein (esp) gene {Scott, 2005 #699} will be performed by Texas AgriLife Research in El Paso to determine if creek segments are being impacted by human or animal fecal pollution. Approximately 50 E. coli isolates from 50 different water samples will be analyzed using the BST methods described below and compared with isolates from the previously developed Texas E. coli source library to determine the need for the development of a local Buck Creek source library. Depending on the results of this BST work, the number of water and source isolates and the types (sewage or animal) of source samples listed below for the second phase may change. That is, if we determine that a larger local Buck Creek source library is needed, we will analyze more source samples and fewer water samples. Conversely, if it appears that the existing Texas source library is suitable for identification of water isolates, more water samples and fewer Buck Creek source samples may be analyzed. This will allow us to provide the most useful BST results within funding limitations. The second portion of the BST work will involve the development of a local Buck Creek library of E. coli from known sewage and animal sources and BST analysis of E. coli isolated from water samples, with the sampling design dependent on the results of the first BST assessment. An experimental approach flow diagram is presented in Figure 1.

Texas AgriLife Research in Vernon will be responsible for collecting, processing, and isolating E. coli from water and fecal samples. E. coli will be isolated from the samples using standard microbiological methods as previously used in TSSWCB and TCEQ source tracking projects. E. coli will be isolated from water samples using USEPA Method 1603 and modified mTEC medium. Fecal specimens or domestic sewage samples will also be streaked (resuspended in buffer if necessary) onto modified mTEC medium. The use of modified mTEC medium for isolation of E. coli from both water and source samples will help avoid selection of different types of E. coli due to different media. Texas AgriLife Research in Vernon will ship bacterial cultures to the Texas AgriLife Research El Paso Environmental Microbiology Laboratory (Di Giovanni) for BST analyses.

E. coli source isolates will be selected using an approach to maximize the diversity of strains represented in the library. Texas AgriLife Research in El Paso will screen confirmed E. coli bacterial colonies with the repetitive sequence polymerase chain reaction (PCR) method, Enterobacterial Repetitive Intergenic Consensus-PCR (ERIC-PCR). This method will be used to identify unique E. coli isolates from each sample and eliminate further analysis of identical isolates (clones). At least one E. coli isolate from each fecal, wastewater, etc. sample will be included in the library, even if it is identical to a previously isolated E. coli. Therefore, abundant/common strains will be sufficiently represented in the libraries. It is anticipated that over 300 E. coli colonies from approximately 100 source samples will be screened. Of those, approximately 100 will be selected for further BST analysis and inclusion in the source identification library.

A total of 500 E. coli isolates obtained from ambient water samples will be characterized. DNA patterns of those isolates will be compared to the Buck Creek E. coli source library as well as Texas AgriLife Research in El Paso's library of over 1,900 E. coli isolates from known animal and human sources collected throughout Texas. Water isolates will be identified to cattle, other livestock, avian and non-avian wildlife, domestic sewage, and pet sources.

Further information on the methods used can be found in the project workplan.

Evaluation of Alternative Implementation Measures

A science-based assessment of potential mitigation options for problem animal species will then be developed. This work will be conducted with significant input from landowners in the project area. Their input on which practices are acceptable and economically advantageous to them is critical to the management practice selection process. Management practices selected will be focused on a targeted source of bacteria but may have ancillary benefits to species other than the targeted one. Practices that will likely have the most significant impact for reducing bacterial loading to the creek will be included in the Watershed Protection Plan for Buck Creek.

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