The Twin Creek Watershed TMDL

Background

The Twin Creek Total Maximum Daily Load (TMDL) report was approved by U.S. EPA on March 4, 2010. TMDL reports identify and evaluate water quality problems in impaired water bodies and propose solutions to bring those waters into attainment with water quality standards.

The Twin Creek watershed drains 316 square miles of southwest Ohio. Twin Creek is a subwatershed of the Great Miami River and covers portions of Darke, Preble, Montgomery, Butler and Warren counties. Larger municipalities include Lewisburg, West Alexandria, Germantown and Gratis.

Ohio EPA conducted a comprehensive physical, chemical and biological survey of the Twin Creek watershed in 2005 and several problems were identified. The survey results were published in October 2007 (see below). Major causes of impairment were bacteria, sediment and habitat. Major sources were agricultural and urban land uses, municipal wastewater treatment plants and failing home sewage treatment systems.

Potential solutions include habitat improvement and stream restoration, reduction of nutrients through agricultural best management practices, fixing and replacing failing home sewage treatment systems, and improved treatment and operation at the Lewisburg WWTP.

TMDLs were prepared for bacteria, sediment and habitat. A 4B alternative justification, aimed at correcting in-stream impairment via the NPDES permit, was prepared to address phosphorus and organic enrichment in Twin Creek downstream of the Lewisburg WWTP.

The TMDL Report

• Final TMDL Report without appendices [PDF 1,910K]
  • Appendix A: Qualitative Habitat Evaluation Index Analysis [PDF 317K]
  • Appendix B: Justification for the Use of a 4B Alternative [PDF 22K]
  • Appendix C: Recreation Use Analysis [PDF 44K]
  • Appendix D: Home Sewage Treatment System Calculations [PDF 16K]
  • Appendix E: Implementation Actions and Reasonable Assurances [PDF 136K]
  • Appendix F: Response Summary to Public Comments on the Twin Creek TMDL Report [PDF 15K]

Many of the documents referenced in the TMDL report can be found under Forms and Publications on the Ohio EPA Division of Surface Water Web page.

Supplemental Information

The following documents provide background information on the Twin Creek watershed.

• Fact Sheet. Twin Creek Watershed TMDL Report. March 2010. [PDF 195K]
• Biological and Water Quality Study of Twin Creek and Select Tributaries 2005. Darke, Preble, Montgomery, and Warren Counties, Ohio. October 22, 2007. Ohio EPA Technical Report EAS/2007-10-03.
  • Report [PDF 3,587K]
  • Appendices [PDF 1,365K]

Groups Active in the Watershed

• Three Valley Conservation Trust
• Miami Conservancy District
• Five Rivers Metroparks
• Miami University Institute of Environmental Studies

For more information contact:

Marianne Piekutowski
Ohio EPA, Southwest District Office
Division of Surface Water
401 E. Fifth Street
Dayton, Ohio 45402
marianne.piekutowski@epa.state.oh.us 

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