Harpeth River, Tennessee Final Reconnaissance Report May 2012 The Cover Photo of the Harpeth River near Franklin, Tennessee is Courtesy of Dorene Bolze, Harpeth River Watershed Association Executive Summary The Harpeth River of middle Tennessee (Figure 1) is a tributary to the Cumberland River. The Harpeth River Watershed, which contains over 1,000 miles of streams, is subject to frequent minor flooding and major flooding every few decades, with the most recent major flood occurring in May 2010. The May 2010 flood event saw devastation throughout the watershed, causing 4 fatalities and over $480 million in direct economic damages in the Harpeth basin alone. The watershed also provides habitat to 6 federally listed endangered species in addition to one snail species which is found only in the Harpeth River Watershed. This preliminary analysis finds federal interest in pursuing further study of both flood risk management problems and ecosystem restoration opportunities throughout the basin. In May 2010, middle Tennessee experienced a record storm event. The Harpeth River Watershed saw more rain over a 2-day period than anywhere else in the middle Tennessee area, reaching up to 18 inches in some areas. This event caused record flood stages and unprecedented damages throughout the basin. Although the recurrence frequency of the May 2010 event is relatively low, the Harpeth River Watershed has a long history of significant flood events every few decades, with previous major flooding also occurring in March 1975. With recent population and development growth in the basin in the last few decades, the recurrence frequency of significant flood events, as well as damages associated with them, are expected to increase. From 2000 through 2010, Williamson County, which accounts for the majority of the Harpeth Basin, saw a 44.7% increase in population. In addition to staggering damage figures from the May 2010 event, preliminary, reconnaissance-level analysis has found over 850 structures in the currently regulated floodplain within the basin, including several structures recognized by FEMA as repetitive loss structures. Preliminary analysis shows these flood risks can be effectively managed with both structural and nonstructural measures, with regional high-flow detention measures showing much promise. The Harpeth River also is or has been home to several federally and state listed species. The recent population growth and corresponding increased urbanization has negatively impacted the quality of aquatic habitat. Aquatic ecosystem restoration measures have been identified that will improve the quality of the aquatic habitat so that the Harpeth can be restored and potentially be considered for repopulation of threatened and endangered species. The Harpeth River Watershed is one of great regional and national significance and therefore garners the attention of many agencies. The Harpeth River Watershed Association (HRWA), a non-profit organization, is “dedicated to preserving and restoring the ecological health” of the basin since 1999 (HRWA 2012). Numerous federal, state, and local agencies are partnering with the HRWA to remove a low-head dam on the river in the fall of 2012. Once the dam is removed, the Harpeth River will be a free-flowing river from its mouth to its headwaters, making it one of only a few free-flowing rivers in Tennessee (HRWA 2012). Through this dam removal effort on the Harpeth River, the watershed has gained national attention through the federal agencies collaborating on the project. Also, as a result of the project, the Harpeth River was listed as one of the National Fish Habitat Action Plan’s top 10 “Waters to Watch” for 2012. Harpeth River, Tennessee i Final Reconnaissance Report May 2012 Four streams within the Harpeth River Watershed are listed on the Nationwide Rivers Inventory as “free-flowing rivers that are believed to possess one or more outstanding natural or cultural values”; they are Big Turnbull Creek, Harpeth River, Jones Creek, and the South Harpeth River. Tennessee’s Scenic River Program “seeks to preserve valuable selected rivers, or sections thereof, in their free- flowing natural or scenic conditions and to protect their water quality and adjacent lands.” A portion of the Harpeth River, within Davidson County, is designated under the Tennessee Scenic Rivers Program and includes portions of the Little Harpeth, Harpeth, Trace Creek, Flat Creek, Buffalo Creek, Newsom Branch, Beech Creek, and Turner Creek (TDEC 2000). Cheatham and Williamson Counties, Tennessee, are also eligible for listing portions of the river and tributaries as designated state scenic rivers. The study team recognizes that the flood risk and ecosystem issues identified in this report are analyzed at a reconnaissance level. Measures proposed to address known flooding issues are not limited to those found in this report and will be studied in depth in the feasibility phase of study. Figure 1 - The Harpeth River Watershed, located in Middle Tennessee, just southwest of downtown Nashville. Harpeth River, Tennessee ii Final Reconnaissance Report May 2012 Table of Contents 1. Study Authority 1 2. Study Purpose 2 3. Location of Study, Non-Federal Sponsor, and Congressional Districts 2 4. Prior Reports and Existing Projects 4 5. Plan Formulation 6 5.1. National Objectives 6 5.2. Public Concerns 6 5.3. Problems & Opportunities 7 5.4. Inventory & Forecast Resource Conditions 21 5.5. Planning Objectives 37 5.6. Planning Constraints 37 5.7. Measures to Address Identified Planning Objectives 38 5.8. Preliminary Plans 39 5.9. Conclusions from the Preliminary Screening 41 5.10. Establishment of a Plan Formulation Rationale 42 5.11. Environmental Impacts of Proposed Actions 42 6. Federal Interest 42 7. Preliminary Financial Analysis 43 8. Assumptions, Expectations, and Quality Objectives 43 9. Feasibility Phase Milestones 44 10. Feasibility Phase Cost Estimate 44 11. Views of Other Resource Agencies 44 12. Potential Issues Affecting Initiation of Feasibility Phase 44 13. Recommendations 45 Appendix A: Acronyms & Abbreviations Appendix B: Study Area Maps Appendix C: Scoping Letter, Responses, & Letters of Intent Appendix D: Hydrology & Hydraulics Appendix E: Hazardous, Toxic, & Radioactive Waste Appendix F: References Harpeth River, Tennessee iii Final Reconnaissance Report May 2012 (This page intentionally left blank for two sided printing) Harpeth River, Tennessee iv Final Reconnaissance Report May 2012 1.0 Study Authority 1.1. Initial Authority This Reconnaissance Study Analysis was prepared under the original authority provided by the United States Senate Committee on Public Works Committee Resolution, adopted September 19, 1973, which reads as follows: “Resolved by the Committee on Public Works of the United States Senate, That the Board of Engineers for Rivers and Harbors […] is hereby requested to review the report of the Chief of Engineer on the Cumberland River and Tributaries, published as House Document Numbered 761, 79th Congress, and other pertinent reports, with a view to determining whether any modifications of the recommendations contained therein are advisable at the present time, with particular reference to providing a plan for the development, utilization and conservation of water and related land resources of the metropolitan region of Nashville, Tennessee, with due consideration for the metropolitan planning activities in the eight county area, consisting of Cheatham, Dickson, Montgomery, Robertson, Rutherford, Sumner, Williamson, and Wilson Counties, Tennessee. Such study will include appropriate consideration of the needs for protection against floods, wise use of flood plain lands, bank and channel stabilization, navigation facilities, regional water supply and waste management facilities systems, general recreational facilities, enhancement and control of water quality, and enhancement and conservation of fish and wildlife and will provide significant emphasis on measures for environmental, economic and human resources development. The study should give appropriate consideration to other Federal, state and local planning activities in the eight-county metropolitan area.” 1.2 Appropriations & Authorizations Following the May 2010 Nashville Flood, funds in the amount of $100,000 were appropriated in Fiscal Year 2010 to conduct the reconnaissance phase of the study. This includes an analysis and documentation of existing information on the state of water resources in the watershed, as well as preparation of a scope for a feasibility study that will further address problems identified in the reconnaissance analysis. Funding was initially appropriated under Chapter 4, Title 1, of P.L. 111-212, which states: “For an additional amount for “Investigations,” $5,400,400: Provided, that funds provided under this heading in this chapter shall be used for studies in States affected by severe storms and flooding…” These funds expired prior to their allocation, and P.L. 111-242 allows the full appropriation of P.L. 111- 212 to remain available until expended, for investigations. Thus, appropriations were received in December of 2010 under Section 120.b of P.L. 111-242, which states: “there is appropriated to the Department of the Army, Corps of Engineers, an amount equal to the unobligated balance rescinded by subsection (a), to remain available until Harpeth River, Tennessee 1 Final Reconnaissance Report May 2012 expended, for investigations; (2) that such amount be available on the date of enactment of this Act; and (3) the