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Geronimo and Alligator Creeks: Watershed Protection Plan Implementation

Several grant-supported projects implemented the Geronimo and Alligator Creeks Watershed Protection Plan through septic system remediation, bacteria source tracking, and extensive education and outreach programs.

Map of the Geronimo and Alligator Creeks watershed with stream segments.

Project Area

River Basin: Guadalupe

Water Body: Geronimo Creek (1804A)

Location: City of Seguin


Geronimo Creek originates near New Braunfels and empties into the Guadalupe River south of Seguin. Since 2006, the lower portion of the creek in and near Seguin did not meet water quality standards for primary contact recreation use due to elevated bacteria levels and had concern for high nitrate-nitrogen concentrations since 2000.

Local stakeholders developed a watershed protection plan (WPP) for Geronimo Creek and its major tributary, Alligator Creek, to address the water quality issues. The WPP was accepted by the U.S. Environmental Protection Agency in September 2012.

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Project Descriptions

September 2013 – August 2016

The City of Seguin extended sanitary sewer service into areas with recurring septic system problems and used grant funding to provide financial assistance for the decommissioning of 131 septic systems in those areas.

December 2014 – May 2019

The Guadalupe-Blanco River Authority (GBRA) and the Seguin Outdoor Learning Center (SOLC) collaborated and constructed best management practices (BMPs) at SLOC that served as an outdoor classroom area where residents can learn about nonpoint source pollution, low impact development, and other BMPs. Digital kiosks, portable presentations, and public service announcements were used to introduce watershed residents to the demonstration BMPs and their benefits.

August 2018 – February 2023

GBRA assisted the Geronimo and Alligator Creek Watershed Partnership to characterize sources of bacteria in the watershed through bacteria source tracking (BST) monitoring and disseminated results of the BST study at stakeholder meetings. Source identification led to more targeted and effective outreach and education. GBRA and Texas A&M University collected monthly water samples from Geronimo Creek.

In addition, GBRA expanded the education and outreach efforts that began with the previous implementation project. They filled a part-time environmental education site coordinator position who worked with two area school districts to develop and promote environmental education programs that satisfied the state-mandated Texas Essential Knowledge and Skills (TEKS), and facilitated field trips to SOLC.

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For More Information

GBRA's Geronimo and Alligator Creeks webpage

To find out more about the NPS Program, call 512-239-6682 or email us at

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