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

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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 amount is designated as an emergency requirement and necessary to meet emergency needs pursuant to sections 403(a) and 423(b) of S. Con. Res. 13 (111th Congress), the concurrent resolution on the budget for fiscal year 2010.”

2.0 Study Purpose The purpose of the reconnaissance study is to determine the federal interest in participating in a cost shared feasibility study addressing water resource problems in the Harpeth River Watershed. The reconnaissance study was initiated on August 15, 2011, and has found federal interest in continuing the study of both flood risk management (FRM) and ecosystem restoration into the feasibility phase. The purpose of this Section 905(b) Analysis is to document the basis for this finding and establish the scope of the feasibility phase. This document covers a wide range of water resources-related problems and opportunities that the study team has identified throughout the watershed. These issues range from flood risk and life safety issues to aquatic ecosystem issues. 3.0 Location of Study, Non-Federal Sponsor, & Congressional Districts 3.1 Location The area of study for this effort is the Harpeth River Watershed in its entirety. The Harpeth River Watershed, Figure 2, covers 870 square miles in middle Tennessee, and includes portions of Williamson, Cheatham, Dickson, Davidson, Hickman, and Rutherford Counties. The main stem of the Harpeth River meanders northwesterly for 125 miles, and is fed by over 1,000 miles of tributaries. Major population centers in the watershed include the Cities of Bellevue, Brentwood, and Franklin. The Harpeth River is formed by the confluence of Concord Creek and Puckett Branch at its headwaters in southwestern Rutherford County. The Harpeth River’s confluence with the Cumberland River occurs at Cumberland River Mile 152.9, approximately four miles upstream of Cheatham Dam.

3.2 Non-Federal Sponsor Currently, letters of intent have been received from the City of Nashville, the City of Franklin, and Williamson County, indicating interest in ecosystem restoration and flood risk management work in the watershed (Appendix C). Planning for the feasibility phase and coordination with these sponsors is ongoing. Other potential sponsors include the City of Kingston Springs and the City of Brentwood. Regional alternatives have been identified that benefit multiple political jurisdictions. For these promising alternatives, a group of municipalities and counties that benefit from a regional project would comprise the most effective sponsor.

3.3 Congressional Interest The study area lies within the jurisdiction of the following Congressional Districts: • Tennessee’s 4th District: Congressman Scott DesJarlais (R) • Tennessee’s 5th District: Congressman Jim Cooper (D) • Tennessee’s 6th District: Congressman Diane Black (R) • Tennessee’s 7th District: Congressman Marsha Blackburn (R) • Tennessee’s 8th District: Congressman Stephen Fincher (R)

Harpeth River, Tennessee 2 Final Reconnaissance Report May 2012

Figure 2 - The Harpeth River Watershed, located in Middle Tennessee, just southwest of downtown Nashville. Major Cities and Streams are Labeled.

Harpeth River, Tennessee 3 Final Reconnaissance Report May 2012 4.0 Prior Reports and Existing Projects 4.1 Prior Reports The following reports were reviewed as a part of this study: a. Potential Flood Damage Study for Little Harpeth River (Brentwood Area, Tennessee) (August 1978) - Berger Associates prepared this report for the Nashville District under the authority of WRDA 74, section 22, Planning Assistance to States. This report estimated potential average annual flood damages in the 100-yr floodplain of the study reach to total about $140,000, or approximately $487,000 in 2012 dollars. b. Urban Runoff Water Quality Management Study: Harpeth River Basin Above Bellevue, Tennessee (December 1979) – This document, prepared by the Corps, reported the results of two nonpoint water quality surveys performed on the Harpeth River in 1978, one in May and one in November. The goal was to determine pollution loading to streams due to existing land uses in the basin. c. Reconnaissance Report for Flood Damage Reduction: Little Harpeth River (December 1980) – This reconnaissance report by the Corps, prepared under the Metropolitan Urban Study Authority, investigated both structural and non-structural flood risk management alternatives in the Little Harpeth River area. Structural measures proposed included channel widening, concrete-lined channel sections, and a flow diversion channel at Harpeth River Drive around river mile 5.8. Nonstructural measures included ring levees, flood proofing, and raising structures in place, as well as a regional policy such as strict flood plain management for future development. This reconnaissance report recommended further, more detailed study of structural and non-structural alternatives that appeared economically and physically feasible. However, no feasibility study ever materialized out of this recommendation. d. Reconnaissance Report on Flood Damage Abatement, Little Harpeth River, City of Brentwood and Williamson County, Tennessee (January 1982) – This reconnaissance report, which cites a separate authority from the similar reconnaissance report from December of 1980, again looks at flood risk management alternatives on the Little Harpeth River in Brentwood, Tennessee. This reconnaissance study considered channel widening, creating a concrete-lined channel, a flow diversion channel along Harpeth River Drive, and raising structures in place, much like the December 1980 reconnaissance report. It was again determined that some of these alternatives appeared to be economically feasible, and that further study should occur. e. Little Harpeth River Resident Survey (August 1982) - The Nashville Urban Observatory conducted a survey to ascertain the opinions of residents impacted by the flood study. The participants were asked to rank certain alternatives according to their preference. The most-favored alternative was channel widening (62.4% of the respondents) and the least-favored were home- raising (50%) and flood-proofing (34%). f. Little Harpeth River Floodproofing (October 1984) – This is an engineering report prepared by Barge, Waggoner, Sumner & Cannon for the Corps of Engineers that briefly investigates the costs of three alternatives for flood risk management on the Little Harpeth River. These alternatives were:

Harpeth River, Tennessee 4 Final Reconnaissance Report May 2012 • Alternative I – Lowering Harpeth River Drive for approximately 5000 linear feet parallel to the Harpeth River to act as a diversion structure in times of high flows. • Alternative II – Channel widening of existing channel of Harpeth River to account for floodwaters. • Alternative III – Raising in Place. This involved raising 11 buildings to avoid flood damage. g. Metropolitan Region of Nashville, Tennessee: Harpeth River Interim Plan Formulation Briefing Package (November 1987) – The Nashville district identified several feasible site-specific plans to reduce flood damages in Franklin. There were three channelization plans: 1) a cutoff at river mile 81.9 to 84.5; 2) a cutoff at river mile 86.2 to 87.1; and 3) a side channel from river mile 86.2 to 87.3. Each of these plans had Benefit/Cost Ratios (B/C) ratios of 1.0 or greater at the time. There were also scattered residential structure raises that were identified and floodproofing at the Georgia Boot Company that had B/C ratios of 1.0 or greater. This report further indicated that, in 1987, levee/floodwalls at Rebel Meadows (RM 83.6 to 84.6), Lancaster Drive (86.2 to 87.0), Ewingville Drive (87.8 to 89.1) and Downtown (86.5 to 87.5) were infeasible due to low B/C ratios. This may need reevaluation in current dollars. Additionally, the 1987 study indicated that tributary dams on Nelson Creek, McCrory Creek, Arrington Creek and Mayes Creek have the potential to decrease downstream discharges by 30%. Mainstem dams were dropped from the study. Dam alternatives may not have been acceptable to the local sponsor at that time. h. Reconnaissance Report, Section 205 Flood Control Study: Harpeth River, Williamson County, Tennessee (February 1992) – This reconnaissance report investigates the possibility of adding flood risk management opportunities to the planned I-840 through Williamson County, Tennessee. A dry dam as a part of a bridge over the Harpeth River was considered as the primary alternative, and it was determined that its estimated costs did not warrant further study. i. The Tennessee Department of Environment and Conservations (TDEC) Water Quality Management Plan for the Harpeth River Watershed (05130204) of the Cumberland River Basin (November 2000). This management plan looks at a watershed management approach to water quality with four main features typical of this approach: “1. Identifying and prioritizing water quality problems in the watershed, 2. Developing increased public involvement, 3. Coordinating activities with other agencies, 4. Measuring success through increased and more efficient monitoring and other data gathering.” 4.2 Existing FRM Projects There is only one known prior FRM project in the Harpeth Basin; at one time, a high flow channel was constructed at Cottonwood Subdivision, but the current condition is unknown. The relief channel was constructed from River Mile 78.2 to 79.1 in connection with the Cottonwood Subdivision. The channel was projected to reduce stages by up to 1.5 feet.

4.3 Existing Federal Projects This report does not recommend modifications to any existing federal project. The only federal project that exists in the area is Cheatham Dam on the Cumberland River. The purpose of Cheatham Dam is navigation and hydropower, and does not have flood control storage. This prevents the project from

Harpeth River, Tennessee 5 Final Reconnaissance Report May 2012 having any affect on flooding along the Harpeth River, such as backwater effects if flood control storage was available and filled above the dam. 5.0 Plan Formulation During a study, the six planning steps set forth in the Water Resource Council’s Principles and Guidelines are repeated to focus the planning effort and eventually to select and recommend a plan for authorization. The six planning steps are: 1) specify problems and opportunities, 2) inventory and forecast conditions, 3) formulate alternative plans, 4) evaluate effects of alternative plans, 5) compare alternative plans, and 6) select recommended plan. The iterations of the planning steps typically differ in the emphasis that is placed on each of the steps. In the early iterations, those conducted during the reconnaissance phase, the step of specifying problems and opportunities is emphasized. That is not to say, however, that the other steps are ignored since the initial screening of preliminary plans that results from the other steps is very important to the scoping of the follow-on feasibility phase studies. The sub- paragraphs that follow present the results of the initial iterations of the planning steps that were conducted during the reconnaissance phase. This information will be refined in future iterations of the planning steps that will be accomplished during the feasibility phase.

5.1 National Objectives

The national, or federal, objective of water and related land resources planning is to contribute to national economic development consistent with protecting the nation’s environment, pursuant to national environmental statutes, applicable executive orders, and other federal planning requirements. Contributions to National Economic Development (NED) are increases in the net value of the national output of goods and services, expressed in monetary units. Contributions to NED are the direct net benefits that accrue in the planning area and the rest of the nation.

The Corps has added a second national objective for Ecosystem Restoration in response to legislation and administration policy. This objective is to contribute to the nation’s ecosystems through aquatic ecosystem restoration, with contributions measured by changes in the amounts and values of habitat.

5.2 Public Concerns

A number of public concerns have been identified during the course of the reconnaissance study. Input was received through coordination with potential sponsors, and some initial coordination with other agencies. Agency and public concerns related to the establishment of planning objectives and planning constraints are:

• Flood Risk Management • Quality of Aquatic Ecosystem • Wasteload Assimilation/Dissolved Oxygen Levels • Erosion and Sedimentation throughout the Watershed • Watershed Management • Stormwater & Stormwater Design Standards • Water Supply • Environmental Contaminants in the Basin

Harpeth River, Tennessee 6 Final Reconnaissance Report May 2012 5.3 Problems & Opportunities

The evaluation of public concerns often reflects a range of needs, which are perceived by the public. This section describes these needs in the context of problems and opportunities that can be addressed through water and related land resource management.

Problems within the Harpeth River watershed are related to risk of flooding, sedimentation from streambank erosion, degradation of water quality from sedimentation and other contaminants due to construction sites, urbanization, agricultural practices, and eroding cultural resources sites. The impacts these problems could have on the public, fish and wildlife, water quality, and degradation and/or loss of habitat could be addressed by proactive measures within the watershed. Problems and opportunities identified within the Harpeth River Basin are discussed in detail below.

5.3.1 Flood Risk Management Problems & Opportunities

Flooding in the Harpeth Basin typically occurs in the winter or early spring, and can last up to three days in duration. Backwater from the Cumberland River can extend upstream on the Harpeth River to approximately Harpeth River Mile 6.0. As is evident from the flood history in Section 5.4.12, the Harpeth has a history of repeated major flooding. There are several bridges that produce backwater flooding issues; major bridges on the Harpeth River include I-40, U.S. 70, State Route (SR) 100, S.R. 49, McCrory Lane, Newsome Station Road, Old Harding Pike, Sneed Road, Moran Road, Temple Road, Old Natchez Trace, and Cotton Road. There are also seven railroad crossings along the Harpeth River. All of these crossings have the potential to cause backwater flooding during high flow events.

The most recent major flood in the Harpeth River Watershed, the May 2010 flood, caused immense damage throughout the basin and was responsible for four fatalities. From the City of Franklin to the mouth of the river, homes, schools, and businesses were inundated and destroyed. In some cases, flood depths were up to six feet above the 500 year flood stage. As aforementioned, direct economic damages associated with the flood were estimated in excess of $480 million in a basin of which the largest population center barely exceeds 60,000 people, as of the 2010 Census.

This flood event was promptly declared a federal disaster (Disaster Number 1909). Figure 3 shows the FEMA Individual Assistance (IA) Applications that were submitted in the wake of the May event. This figure represents residential applications for federal post-disaster assistance only and does not even include commercial or public damage claims; there are over 65,000 residential applications throughout the basin. The map shows that high concentrations of IA applications were found in Franklin, Brentwood, and Bellevue areas, the major population centers on the Harpeth River (Franklin and Bellevue) and Little Harpeth River (Brentwood), but it also shows that claims are spread over the entire basin.

Harpeth River, Tennessee 7 Final Reconnaissance Report May 2012

Figure 3 - FEMA Individual Assistance (IA) Applications for the May 2010 Flood Event. Over 65,000 applications are shown in the Harpeth Basin, with damages widespread and concentrations at the population centers.

Harpeth River, Tennessee 8 Final Reconnaissance Report May 2012 Watershed Flood Risk Managment Analysis

In the analysis of the watershed from a flood risk management (FRM) perspective, the basin was divided into two sections based on the quality of available information; these two sections are the basin from the mouth of the Harpeth through Bellevue and the basin above Bellevue. Additionally, information from Nashville’s Unified Flood Preparedness Plan, and analysis ongoing at the time of this writing, is included in this report.

Flood Risk Management Reconnaissance: Mouth through Bellevue, Tennessee

From the mouth of the Harpeth River through Bellevue (RM 0 through RM 61.8), the Corps developed high quality modeling through a partnership with Metro Nashville. The portion of the Harpeth River upstream of Bellevue was beyond the scope of the partnership with Metro Nashville, and the available information was not of high enough quality to produce reliable hydraulic modeling, thus none were available.

An analysis from the mouth through Bellevue yielded fourteen primary damage centers, for which more detailed information and maps can be found in Appendix D. These fourteen damage centers range from Kingston Springs to Bellevue. Below Kingston Springs, the Harpeth River watershed is largely rural and undeveloped, and thus did not have concentrated damage areas. This is apparent in both the NLCD data map (Figure 11) as well as the FEMA IA application data (Figure 3).

In this reach of the river, the high floodwaters cut off a bend in the river (RM 42.65) and took out several feet of soil, and several homes were completely demolished down to their foundations, shown in Figure 4. The inundation of Kingston Springs Elementary School truncated the remaining school year and caused a late start for the following school year while the building was repaired. Figure 5 shows the level the floodwaters reached in the elementary school, as well as some of the infrastructure damage in Kingston Springs.

The fourteen damage centers identified account for over 734 structures affected by the May 2010 flood in the lower reach of the Harpeth River. Although damages are typically infrequent in this stretch of the river due to the nature of development in this reach as well as successful management of the floodplain (for example, Davidson County requires residential structures to have first floors elevated to four feet above the base flood elevation, and commercial structures must have first floors elevated to one foot above the base flood elevation), both structural and nonstructural measures have been identified to address flood risk issues, including levee/floodwalls, bridge modifications, elevating structures, and evacuating individual structures. Elevation candidates are those that typically only see a few feet of flooding and are not slab-on-grade. Those with deeper flooding would be appropriate for evacuation. More detail on the damage areas and potential measures to address them can be found in Appendix D.

Additionally, as backwater from Cheatham Lake on the Cumberland River can reach several miles up the Harpeth River, there is a potential need for re-establishment of government property lines and flowage easements along Cheatham Lake, including within the Harpeth Basin, to reduce future economic and life risks associated with such backwater flooding.

Harpeth River, Tennessee 9 Final Reconnaissance Report May 2012

Figure 4 – Before (above) and after (below) aerials of homes destroyed on Harpeth View Trail in Kingston Springs, Tennessee during the May 2010 flood event. Images © 2012 Google.

Harpeth River, Tennessee 10 Final Reconnaissance Report May 2012

Figure 5 - High water line in Kingston Springs Elementary School, above, and May 2010 flood devastation to public infrastructure, below

Harpeth River, Tennessee 11 Final Reconnaissance Report May 2012 Nashville / Davidson County Unified Flood Preparedness Plan

Through Metro Nashville’s Unified Flood Preparedness Plan, an effort ongoing at the time of this writing, Metro Nashville and the Corps ran a preliminary analysis on an array of flood risk management measures for the reach of the Harpeth River within Davidson County. Measures considered include bridge modifications, levees, a diversion channel, and a high flow detention reservoir.

The high flow detention reservoir, proposed at Lampkins Bridge Road in Arrington, showed the most promise for being able to significantly reduce flood stages throughout much of the main stem of the river, and does warrant federal interest. A high flow detention reservoir is one that does not impede natural stream flow, only higher flow events. The flow that leaves the reservoir would be far less than that of high flow events at existing conditions. The outlet structure could be designed to only release a specific amount of water (say the 10-year flood) and could allow both recreational users and wildlife passage up and downstream. The location of the proposed detention system, upstream of the City of Franklin, also allows for Franklin and Williamson County, in addition to Davidson County, to appreciate benefits from such a project. Additional alternatives considered as a part of this effort warranted further study as well, as shown in Appendix D.

Flood Risk Management Reconnaissance: Upstream of Bellevue, Tennessee

The major damage centers upstream of Bellevue are Brentwood, on the Little Harpeth River, and Franklin, on the Harpeth River. Limited data is available for analysis on this upper reach. Structures at risk in the upper reach of the Harpeth were identified using aerial imagery and the best available inundation information.

This reach of the Harpeth, stretching from approximately River Mile 61.8 to the headwaters, also saw significant damage in the May 2010 flood event, as is evidenced by the FEMA Individual Assistance application data (Figure 3). There are many structures built in the floodplain, and even in the floodway, along the Harpeth and the Little Harpeth Rivers in this region.

Both the Cities of Brentwood, on the Little Harpeth River, and Franklin, on the Harpeth River, have noted flooding issues, and both experienced major flooding in the May 2010 event. Brentwood has structures located in the Little Harpeth River’s regulated floodplain, many of which also fall in the floodway, and are at very high risk for life safety and property loss. Previous studies have looked at these areas in Brentwood making both structural and nonstructural recommendations for high risk structures in the floodway. Both structural and nonstructural alternatives have been previously found to be economically feasible with positive benefit-to-cost ratios. It is imperative that the high risk structures in Brentwood are further studied to reduce the risk on human life and property.

The City of Franklin has several roads that are routinely inundated during flood events on the Harpeth River. The City of Franklin has also prioritized Sharp’s Branch, a tributary to the Harpeth River, as a location with significant flood risk and in need of restoration. Sharp’s Branch’s propensity for flooding was highlighted in the May 2010 flood event, when many businesses and homes were inundated along

Harpeth River, Tennessee 12 Final Reconnaissance Report May 2012 the stream. Figure 6 shows debris removed from a flooded home in Franklin in the wake of the May 2010 flood.

Both the City of Franklin and Williamson County are currently executing or are planning home buyouts and home buyout plans. In addition, Williamson County is working towards buying out all of the repetitive loss structures in its jurisdiction.

Preliminary analysis, detailed in Appendix D, finds at least 856 structures in the 100 year floodplain of the upper reaches of the Harpeth River Watershed, some of which are also in the 10 year floodplain and even in the floodway. While structural measures such as levees and floodwalls may be appropriate for a select few of the areas identified below, the best measures to address flood risk issues in the upper reaches of the Harpeth Basin are nonstructural or regional high flow detention, as previously mentioned. While the Lampkins Bridge Road high flow detention reservoir does show promise here, other combinations of regional high flow detention structures could also be appropriate.

Figure 6 - Debris removed from a flooded home after the May 2010 flood in Franklin, Tennessee

Flood Risk Management Opportunities in the Harpeth Basin

Opportunities for flood risk management studies that would address both the risk to human life and the risk to property exist within the Harpeth Basin, which regularly experiences damaging floods. Hundreds of structures were damaged in the May 2010 event, and hundreds of structures are found in the

Harpeth River, Tennessee 13 Final Reconnaissance Report May 2012 floodplains of the Harpeth River Watershed. Both structural and nonstructural measures have been found to warrant further study to address these flood risk issues.

Further studies would enable federal, state, and local partners to evaluate flood damages to infrastructure and natural resources such as aquatic habitat, wetlands, streambanks, and riparian zones. Potential methods for flood risk management include structural and nonstructural methods and flood warning evacuation plans.

Nonstructural methods include flood proofing, ring levees, demolish and replace options, and raising-in- place. Certain structures could be considered for flood proofing, ring levees, or evacuation, while others could be considered for raising-in-place, demolishing the structure and replacing, or evacuation. These methods for both commercial and residential structures would lessen impacts during flood events. Examples of structural methods include levees, diversion channels, channel modifications, and detention methods.

Flood Preparedness Plans are an effective way for local governments to reduce risk to human life and property during flood events. After the May 2010 flood event, Nashville initiated a Planning Assistance to States flood preparedness study with the goal of developing tools to better inform decision makers and emergency response. Flood Preparedness Plans could be tailored to the needs of any particular city or county, and can include flood recognition and evaluation, detailed action or response plans, the ability to evaluate the likely consequences of potential flooding, and evacuation procedures. Early and reliable flood warning can prevent loss of life and reduce flood damages.

5.3.2 Ecosystem Problems & Opportunities in the Harpeth Basin

In addition to flooding problems in the Harpeth River Watershed, the basin also faces aquatic ecosystem problems that the Corps could address through its civil works authorities. These problems include, streambank erosion, nutrient loading, water quality conditions for fish and aquatic life, turbidity, runoff (urban and rural), flow alteration, and degradation of wetlands and riparian zones.

Stream reaches assessed in the Harpeth River Watershed by the TDEC and other agencies in Tennessee identify water quality problems based on point and non-point source pollutants. To comply with the Clean Water Act, the TDEC compiled the 303(d) list of the waters of Tennessee that fail to support some or all of their classified uses. Based on the Environmental Protection Agency’s 2010 approved 303(d) list, sixty-six stream reaches, totaling 413.6 miles, are listed as impaired in the Harpeth River and tributaries. Causes for listing include but are not limited to: habitat loss, siltation, physical substrate habitat alternation, nutrients, dissolved oxygen (DO), and Escherichia coli.

The following issues related to aquatic habitat degradation have been identified and are discussed below.

Harpeth River, Tennessee 14 Final Reconnaissance Report May 2012 Wetland & Floodplain Loss

Wetland and floodplain loss negatively affects the quality of habitat and aquatic life within rivers and streams. These features serve as filters for sedimentation and contaminants, spawning areas for fish and other aquatic species, provide buffers and stabilization along streambanks, provide feeding areas, and store water during high flows. Causes for loss include development (urban and rural), channelization, and agricultural practices.

Opportunities for addressing wetland and floodplain loss include educational awareness on the importance of their functions and how they affect aquatic species and their ecosystems. Other opportunities exist to preserve and/or restore wetlands and floodplain areas and could include an inventory of potential wetland areas within the watershed and classification and functional assessment of identified wetlands. The restoration of both floodplain and wetlands would also provide additional benefits that include storing water to supplement streams during low flow periods and filtering storm water runoff entering streams to sustain water quality.

Sedimentation

High sediment loads from loss of riparian zones, agricultural practices, urbanization, and roadside ditches have impacted stream reaches throughout much of the Harpeth River watershed. Suspended sediment impairs streams by silting over the substrate, making them unsuitable for aquatic organisms for spawning, feeding, etc. Fish and other aquatic species are also affected by suspended sediments from reduced light penetration, ultimately affecting food availability.

Opportunities exist to address sedimentation. Restoration of riparian zones or wetlands would create a buffer, capturing and filtering upland sediments, as well as stabilize eroding banks. Implementation of BMP’s such as agricultural berms, single point access, alternate water sources, and silt fencing would help to reduce the amount of sediment entering a stream. Streambank stabilization through stone placement, bioengineering, foreshore dikes, or other methods would also help reduce the amount of sediment entering streams.

One particular site located at City and Burns Parks (Figure 7 and Figure 8) in Kingston Springs, typical of other sites found throughout the watershed, is experiencing severe erosion. An old bridge (Figure 9) just upstream of the parks is in poor condition and there are concerns for public safety, debris buildup, and scouring of the streambed. The bridge’s instream piers are accelerating both erosion and sediment deposits at the site. Potential aquatic ecosystem restoration measures to address problems at this site and others like it include, but are not limited to, bendway weirs that could improve aquatic habitat, foreshore dikes, wetland restoration and/or preservation, and bank stabilization with stone and/or bioengineering methods. Increasing the span of the riparian zone would help stabilize banks and also improve aquatic habitat conditions by decreasing the amount of sediment and contaminants entering the waterway.

Harpeth River, Tennessee 15 Final Reconnaissance Report May 2012

Figure 7 – Severe Erosion at City Park in Kingston Springs, Tennessee

Figure 8 – Sedimentation at Burns Park in Kingston Springs, Tennessee

Harpeth River, Tennessee 16 Final Reconnaissance Report May 2012

Figure 9 – Old Highway Bridge in Kingston Springs, Cheatham County, Tennessee

Nutrient Loading

Nutrient loading refers to disproportionately high concentrations of certain substances, commonly nitrogen and phosphorus, in the aquatic ecosystem. These high levels of nutrients skew the natural balance of the ecosystem and commonly result in increased levels of algae. According to the TDEC’s 2010 305(b) report, “nutrients stimulate algae growth that produces oxygen during daylight hours, but uses oxygen at night, leading to significant diurnal (active during the day) fluctuations in oxygen levels.” These decreased DO levels can leave aquatic habitat without the necessary resources to sustain itself. Nutrient loading can be the result of agricultural and landscaping practices, urban runoff, and municipal wastewater systems.

Opportunities to address nutrient loading include restoration of natural filters such as riparian zones and wetlands. These natural filters would help trap nutrients before they enter streams. Rain gardens or other similar forms of detention also provide natural filtration of nutrients. Implementation of agricultural/construction BMP’s in the watershed would help to reduce pollutants/nutrients entering streams, maintaining aquatic habitat.

In May 2010, flood waters entered the lagoons at the City of Kingston Springs Wastewater Treatment Plant. If lagoons are inundated and not able to continue treatment processes, the plant would have to close until such time as repairs are completed. With closure of the plant, there would be concerns with the release of untreated sewage. Flood risk management methods would potentially address concerns that could arise during high flow events, specifically the exposure of the aquatic habitat of rare fauna to raw, untreated wastewater.

Harpeth River, Tennessee 17 Final Reconnaissance Report May 2012 Flow Alteration

Flow alteration is a change to flow within stream reaches that can increase, decrease or prolong flow. Urban development (impervious surfaces and floodplain encroachment), stormwater practices, and loss of riparian zones and wetlands all contribute to flow alteration within the Harpeth River Watershed. Increases in impervious areas and decreases in infiltration and transpiration result in higher than normal velocities and peak flows during rain events. While decreasing base flow to the streams during normal conditions, manmade detention structures can end up prolonging peak flows and velocities. These increased velocities and flows are more likely to alter instream habitats, not just by washing out substrates, but also by accelerating bank erosion and scour and increasing sediment and debris accumulation. During low flow periods, reduced infiltration impacts the water table, potentially reducing instream flows to little or none. Without flows, aquatic organisms are threatened with the loss of spawning and feeding areas.

Opportunities to address flow alterations revolve around increasing infiltration and transpiration. Such measures could include development of rain gardens, and restoration of riparian zones and wetlands. Floodplain management and increased awareness on a local level and practices such as the use of pervious concretes would help increase infiltration.

Hazardous, Toxic, and Radioactive Waste

Hazardous, toxic, and radioactive materials that are leached or allowed to enter streams can cause issues for aquatic life by introducing contaminants into the aquatic ecosystem. These materials also cause concern for the public when exposed to streams and/or consuming fish. Known hazardous, toxic, and radioactive (HTRW) issues include the leaching of toluene and acetone into Liberty Creek from the Egyptian Lacquer Manufacturing Company’s plant in Franklin, Tennessee. This problem was realized in early 2007 and is being addressed by the TDEC and the Egyptian Lacquer Manufacturing Company. In the College Grove area of the watershed, the former General Smelting plant has left lead and battery chips embedded in the Harpeth River banks. Recently, in early 2012, crude oil has been found bubbling up in areas around Brush Creek in the Harpeth River watershed. Currently the source and how much crude oil is at the source is unknown. In middle Tennessee, it is very unlikely that there are any significant pockets of crude oil from a production standpoint; however, the crude oil does pose an environmental threat to the habitats that it comes into contact with.

A preliminary Hazardous, Toxic, and Radioactive Waste (HTRW) database search was conducted on 15 September 2011 for Dickson County, Williamson County, Southwest Davidson County, and West Rutherford County. The results of this database search are found in Appendix E. During the course of a feasibility study, a Phase I HTRW investigation would be performed at the project site, and all applicable HTRW concerns would be addressed.

Educating the public on the importance of hazardous, toxic, and radioactive materials and their impacts to the aquatic ecosystem provides an awareness that could help reduce the presence of these contaminants.

Harpeth River, Tennessee 18 Final Reconnaissance Report May 2012 5.3.3 Additional Opportunities

Recreation

Recreational opportunities include creating additional access points along the river and its tributaries and could be created from stabilizing banks that have experienced erosion. Additional access points would also provide economic benefits to local and surrounding communities. Greenways would also be an attractive recreational feature in the watershed providing numerous opportunities for the public. Other recreational opportunities involve hiking and camping, especially in local and state parks within the basin.

Fishing is a popular recreational activity throughout the watershed and numerous species would benefit from alternatives that restore riparian zones, ultimately reducing erosion and sedimentation.

Cultural resources would benefit from recreational opportunities such that additional signage would provide educational experiences to the public.

Watershed Management

In addition to opportunities for flood risk management and ecosystem restoration identified in the preceding pages of this 905(b) analysis, opportunities for the better management of the watershed always exist. Historically, watershed systems have typically not been considered holistically when speaking in terms of development, and it is this Epimethean practice that results in development that encroaches in the floodway causing repeated flooding, drastic decreases in pervious areas, and degradation of aquatic ecosystems across the globe. Increasing public awareness to the effects of improperly managed watersheds and the implementation of smarter watershed management practices could greatly reduce both flooding and environmental impacts.

Floodplain Management

Floodplain management within the watershed is actively practiced by the cities and counties with jurisdictions within the basin. Regulations range from requiring elevation of structures within the regulatory floodplain to prohibiting any development within the boundaries of the regulatory floodplain. Since the regulations have evolved over time there are structures that remain within the regulatory floodplain that could benefit from a variety of flood risk management measures. However, there are still opportunities to improve the management of the floodplains in the Harpeth Basin.

Pursuant to Section 209, Floodplain Management Plans, of the Water Resources Development Act of 2000, as amended, and pursuant to Executive Order 11988, the nonfederal sponsor of a Corps flood risk management project must implement a floodplain management plan with the goal of protecting the floodplain. Additionally, federal projects cannot degrade the floodplain or induce degradation to the floodplain unless there is no other practicable alternative for consideration. Executive Order 11988 is aimed at preserving the floodplain from both flood risk and environmental standpoints, and both the Corps and any nonfederal sponsor would maintain this preservation goal.

Harpeth River, Tennessee 19 Final Reconnaissance Report May 2012 Water Supply

As populations in the Harpeth Basin continue to grow, causing water demands to increase and causing infiltration to decrease, the availability of water could eventually become an issue of serious concern. Not only could the availability of water become an issue as population growth continues in the basin, but water quality could continue to degrade as urban runoff increases. The watershed should be managed by all levels of government involved with these potential issues in mind.

Currently, the City of Franklin is proposing a new waste water treatment plant that has an outfall upstream of the City and its water intakes. The waste water treatment plant would augment the flows of the river in low flow months in hopes of allowing sustained withdrawals for water supply. Franklin’s proposal raises the opportunity to add wetlands, or another measure, that would serve to further filter the waste water effluent prior to entering the river.

Stormwater Runoff, Regulations & Design Standards

It has become apparent throughout the watershed that stormwater structure design standards may need to be revisited. Non-riverine flooding is an issue in the basin, largely caused by undersized storm water structures. Storm water structures that may have been properly sized at the time of their placement could later become inadequate with increased development. It would be beneficial throughout the region for development regulations to take a more systematic look at storm water design.

Opportunities for FIS updates

In recent years FEMA has adopted a watershed approach to floodplain management. As part of this approach when FEMA periodically updates Flood Insurance Rate Maps (FIRM) for an area, it will do this on a watershed basis rather than by political boundaries. This helps prevent discontinuity or conflict of information at political boundaries and assures that all information within the watershed is of the same current vintage. In late 2010, FEMA began such an effort in the Harpeth River watershed. Using the hydrologic modeling of the entire basin and the hydraulic model developed by the Corps for the Harpeth River from the mouth to the Davidson/Williamson County line, FEMA began an effort to update the maps within the watershed. FEMA is scheduled to provide updated modeling for streams outside the Corps modeling effort, and to compile all of the updated modeling into a revised set of georeferenced maps for the watershed.

Currently FEMA’s efforts are limited by available funding, and additional opportunities will exist outside of what the USACE has recently modeled and what FEMA is currently updating. Depending on the extents of FEMA’s updates, opportunities for further updates will include populated areas on tributaries to the Harpeth such as the South Harpeth, Little Harpeth, West Harpeth, Turnbull Creek, and Jones Creek, as well as tertiary streams in areas such as Brentwood and Franklin.

Harpeth River, Tennessee 20 Final Reconnaissance Report May 2012 5.4 Inventory & Forecast Resource Conditions

Information gathering is one of the principal tasks of any planning effort, and is divided into two basic types: Inventory and Forecast. Inventory involves gathering existing information, current and historical. Forecast involves gathering information that describes potential future conditions.

The Harpeth River Watershed covers approximately 870 square miles in portions of Cheatham, Davidson, Dickson, Hickman, Rutherford, and Williamson Counties. The scenic Harpeth River meanders northwesterly for 125 miles through Middle Tennessee, and is fed by over 1,000 miles of tributaries. At its confluence, the Harpeth River joins the Cumberland River at river mile 152.9. Major population centers in the Harpeth River Watershed include the Cities of Brentwood and Franklin, in Williamson County; the suburb of Bellevue in Metropolitan Nashville; the Cities of Kingston Springs and Pegram in Cheatham County; and portions of the City of Dickson in Dickson County. The USGS identifies the watershed by an eight-digit hydrologic unit code (HUC) (05130204) and nine 12-digit subbasins. Major tributaries to the Harpeth include the Little Harpeth River; South and West Harpeth Rivers; and Turnbull, Jones, and Brush Creeks.

5.4.1 Ecological Region and Environmental Conditions

According to the TDEC’s Harpeth River Watershed Water Quality Management Plan (2000), “Ecoregions are defined as relatively homogenous areas of similar geography, topography, climate, and soils that support similar plant and animal life.” The Harpeth River Watershed is within the Interior Plateau ecoregion consisting of the following three Level IV subecoregions, also shown below in Figure 10

71f – Western Highland Rim is characterized by dissected, rolling terrain of open hills, with elevations of 400-1,000 feet. Streams are characterized by coarse chert gravel and sand substrates with areas of bedrock, moderate gradients, and relatively clear water. The region is heavily forested with oak-hickory natural vegetation (EPA 1997).

71h – Outer Nashville Basin has rolling and hilly topography and slightly higher elevations. The region’s limestone rocks and soils are high in phosphorus. Deciduous forests with pasture and cropland are the dominant land covers. Streams are low to moderate gradient, with productive nutrient-rich waters, resulting in algae, rooted vegetation, and occasionally high densities of fish (EPA 1997).

71i – Inner Nashville Basin is less hilly and lower than the Outer Nashville Basin. Outcrops of limestone are common and the generally shallow soils are redder and lower in phosphorus. Streams are lower gradient than surrounding regions, often flowing over large expanses of limestone bedrock. The most characteristic hardwoods within the inner basin are a maple-oak- hickory-ash association. The limestone cedar glades of Tennessee, a unique mixed grassland/forest cedar glades vegetation type with many endemic species, are located primarily on the limestone of the Inner Nashville Basin. The more xeric, open characteristics and shallow soils of the cedar glades also result in a distinct distribution of amphibian and reptile species (EPA 1997).

Harpeth River, Tennessee 21 Final Reconnaissance Report May 2012

Figure 10 – Map of Level IV Ecoregions within the Harpeth River Watershed

5.4.2 Climate

The Harpeth River Watershed is located in Middle Tennessee and is characterized by its temperate climate, with warm summers and mild winters. Table 1, below, characterizes differences within the three Level IV subecoregions that make up the Harpeth River Watershed.

5.4.3 State Natural Areas, State Parks, and Scenic Rivers

State Natural Areas in the watershed include Montgomery Bell Designated State Natural Area, which has an oak-hickory forest community of the Western Highland Rim; Radnor Lake Designated State Natural Area, which has an eighty-five acre lake and is one of the state’s first natural areas; Gossett Tract State Natural Area; and Sneed Road Cedar Glade Designated State Natural Area (TDEC 2000). State Parks within the Harpeth River Basin include Montgomery Bell State Park, Radnor Lake (managed by state parks), and Harpeth River State Park (TSP website 2012). Portions of the Harpeth River are designated as scenic rivers under the Tennessee Scenic River Program.

Harpeth River, Tennessee 22 Final Reconnaissance Report May 2012 Table 1 – Climate in the Harpeth River Watershed by Level IV Subecoregion

Sub-Ecoregion Precipitation Frost Free Mean Temperature Mean annual Mean annual January min/max: (inches) (days) July min/max, (F) 71f 50-56 185-205 24/46 65/89 71h 48-54 190-210 25/47 66/89 71i 48-53 190-210 25/46 66/90

5.4.4 Recreation

Many recreational facilities exist throughout the Harpeth River Watershed. Harpeth River State Park has multiple locations along the mainstem of the river offering numerous activities including canoeing, kayaking, swimming, and fishing. This Class I river is utilized by many paddlers, with access points throughout the watershed on the mainstem. Additional recreational facilities within the Harpeth Basin include a one mile greenway in Bellevue, Montgomery Bell State Park, Percy Warner Park, Edwin Warner Park, and the Cheatham Wildlife Management Areas located in Cheatham County, managed by TWRA. Greenways exist along the Little Harpeth River in the City of Brentwood and along the mainstem in the City of Franklin. Fishing is also a popular recreational activity along the river. TWRA stocks trout on a regular basis during the winter and spring months.

The Harpeth River Blueway Project, a joint project between the HRWA and the Tennessee Scenic Rivers Association, is designed to promote “recreational opportunities, safety and the preservation of natural and cultural features along the Harpeth River through the provision of canoe/kayak access and accompanying signage” (HRWA 2011).

5.4.5 Historical Ecological Resource Conditions

According to a report prepared by TRC, Inc. in 2007, historic plant and animal species found in the Harpeth River Watershed and the surrounding region “during the late Pleistocene period were in many ways close to modern species.” Beginning in the Holocene period, temperature changes brought about the demise of megafauna once found in the region, as well as the rise of the deciduous forests that we find today in much of the region.

5.4.6 Fish and Wildlife: Aquatic Resources

The Harpeth River watershed supports a diversity of fish species that include bass and sunfish (family Centrarchidae), channel catfish (Ictalurus punctatus), minnows (family Cyprinidae), darters (family Percidae), and many other fish species. Macroinvertebrates found throughout the watershed include crayfish (Order Decapoda), stoneflies (Order Plecoptera), mayflies (Order Ephemeroptera), dragonflies

Harpeth River, Tennessee 23 Final Reconnaissance Report May 2012 (Order Odonata), damselflies (Order Odonata), snails (Order Stylommatophora), and other organisms. Mussel species are also present within the watershed and surveys conducted revealed twenty-eight species, as well as the Asian clam (Corbicula fluminea). Other species found include fingernail clams (Sphaerium spp.) (Hubbs et al. 2002).

Surveys conducted throughout the watershed have revealed several aquatic species. In 1997 and 1998, a survey was conducted in the Kelley Creek Watershed (a tributary to South Harpeth Creek, tributary to the South Harpeth River). Thirty-two species of fish were identified that included sunfish species, sculpin, suckers, and various minnows and nearly 100 aquatic macroinvertebrates. Other fish species included dace, chub, and darters. During this survey one particular species, the blacknose dace (Rhinichthys atratulus) was identified. This is the only known occurrence of the dace within the entire Harpeth River system. The blacknose dace is common and found in the Cumberland, Tennessee, and Ohio River systems; however, if populations have been “reproductively isolated long enough, this newly discovered Harpeth system population could potentially be determined to be a distinctive or unique taxon in future studies” (Rakes et al. 1998).

A snail species, the sharp-tongued rocksnail (“Lithasia” spicula sp. nov.), was found in 2005, by Russell et al. This occurrence in the Harpeth is the only known occurrence of this species anywhere. The rocksnail’s habitat includes shoals under and downstream of the Highway 100 Bridge. According to Russell et al., this species is “restricted to an extremely short stretch of the Harpeth River, it should be treated as rare and measures should be taken to protect it and the surrounding river environment” (Russell et al.).

In 2006, a survey was conducted at 6 sites on the mainstem of the Harpeth River near Franklin, Tennessee. A minimum of 97 benthic macroinvertebrate species and a minimum of 33 fish species were identified. The small scale darter (Etheostoma microlepidum) was identified and is considered in need of management by TDEC’s Guide to the Rare Animals of Tennessee (Pennington & Associates, 2006).

In the spring of 2008, the TWRA surveyed two sites, in Franklin, Tennessee, upstream and downstream of the low head dam that is to be removed. Three mussel species were collected at site 1 and one live mussel and relic shells of the Tennessee pigtoe (Fusconaia barnesiana) and pocketbook (Lampsilis ovata) at site 2. Darters and live Asian clams were also common at site 2. Results from the survey indicate that limited populations exist below the dam and reaches upstream of the dam, at this time, do not support mussel populations (TWRA 2008). In June of 2010, the TWRA conducted fish surveys at four sites along the Harpeth River, near the dam, collecting 47 different species. TWRA has plans to conduct additional surveys a few years after the restoration project in which the dam will be removed (TWRA 2011).

In 2002, Steve Ahlstedt surveyed the Harpeth River with TWRA at seven sites within Rutherford, Williamson, Davidson, Dickson, and Cheatham counties. Information was needed to determine if certain sites in the Harpeth River are favorable for mussel restoration based on diversity and suitable habitat. According to Ahlstedt, in consultation with Dr. Paul Parmalee, the Harpeth possibly contained at least 50 mussel species historically, based on surveys from the Cumberland, Stones, and Caney Fork mainstems. Ahlstedt also indicated that no mussel information is known in Jones Creek, South or West Harpeth, or

Harpeth River, Tennessee 24 Final Reconnaissance Report May 2012 the Little Harpeth and that “the possibility may exist that sites can be found in these streams for future mussel restoration.” According to information presented in the report, three federally listed mussel species have been reported from the Harpeth: pink mucket (Lampsilis abrupta); oyster mussel (Epioblasma capsaeformis); and winged mapleleaf (Quadrula fragosa). The oyster mussel and the winged mapleleaf no longer exist in the Harpeth (Ahlstedt, 2002). Four species of “special concern” were recorded during this survey in 2002; the phesantshell (Actinonias pectorosa), purple wartyback (Cyclonaias tuberculata), plain pocketbook (Lampsilis cardium), and round hickorynut (Obovaria subrotunda) (TWRA 2002).

The tan riffleshell, a federally listed endangered species, historically has been known to exist within the watershed. The riffleshell tends to inhabit coarse substrate in riffle areas in small to medium rivers. Reasons for decline include impoundments, siltation, and pollution (USFWS 1984).

5.4.7 Fish and Wildlife: Terrestrial Resources

Vegetation found in the basin varies from the headwaters to the mouth of the Harpeth and throughout its tributaries. Upper portions of the Harpeth River Basin have flatter areas with shallow bedrock. Limestone cedar glades are also unique to this area of the basin and vegetation types (grassland/forest cedar glades) exist that include endemic species. The middle to lower portion of the basin consists of rolling hills and higher elevations. The river through these areas has wide meanders with steep limestone bluffs on the outer bends and wide flat floodplains on inside bends. The Tennessee Wildlife Resources Agency (TWRA) manages the Cheatham WMA located within the lower basin. The WMA lies in Cheatham County and consists of 20,810 acres with portions located in the lower basin of the Harpeth River Watershed (TWRA 2012).

Common tree species found within the basin include oak (Quercus spp.), ash (Fraxinus spp.), maple (Acer spp.), dogwood (Cornus spp.), sycamore (Platanus occidentalis), hickory (Carya spp.), redbud (Cercis canadensis), persimmon (Diospyros virginiana), and tulip popular (Liriodendron tulipifera). Riparian areas provide habitat and support many different species of wildlife. Common species found throughout the watershed include white-tailed deer (Odocoileus virginianus), wild turkey (Meleagris gallopavo), squirrel (Sciurus spp.), eastern cottontail (Sylvilagus floridanus), raccoon (Procyon lotor), opossum (Didelphis virginiana), mourning dove (Zenaida macroura), red fox (Vulpes vulpes), gray fox (Urocyon cinereoargenteus), wood duck (Aix sponsa), belted kingfisher (Ceryle alcyon), and many species of amphibians and reptiles.

5.4.8 Threatened and Endangered Species

Fifty-eight species and one ecological system throughout the watershed are state and/or federally listed as endangered, threatened, candidate, species of concern, or deemed in need of management. Table 2, below, identifies those species and their given status.

Harpeth River, Tennessee 25 Final Reconnaissance Report May 2012 Table 2 – State and Federally Listed Flora and Fauna within the Harpeth River Watershed

State Federally Scientific Name Common Name Protected Protected Mussels

Epioblasma florentina walkeri tan riffleshell E LE

Snails Rare, Not Lithasia duttoniana helmet rocksnail State Listed Rare, Not Lithasia geniculata fuliginosa geniculate river snail State Listed State Federally Scientific Name Common Name Protected Protected Insects Rare, Not Ophiogomphus acuminatus acuminate snaketail State Listed Plants Acalypha deamii Deam’s Copperleaf S ridge-stem false- Agalinis oligophylla E foxglove Amsonia tabernaemontana var. gattingeri limestone blue star S Apios priceana Price’s potato bean E LT Western hairy Arabis hirsuta T rockcress Arabis perstellata Braun’s rockcress E LE

Asclepias purpurascens purple milkweed S

Astragalus bibullatus Pyne’s ground plum LE

Astragalus tennesseensis Tennessee milk-vetch S

Carex davisii Davis’ sedge S

Carex gravida heavy sedge S hairy sharp-scaled Carex oxylepis var. pubescens S sedge Castanea dentata American Chestnut S

Crataegus harbisonii Harbison’s hawthorn E

Dalea foliosa leafy prairie- clover E LE

Erythronium rostratum beaked trout-lily S

Evolvulus nuttallianus evolvulus S

Harpeth River, Tennessee 26 Final Reconnaissance Report May 2012 State Federally Scientific Name Common Name Protected Protected sweet-scented Hasteola suaveolens T Indian-plantain Helianthus eggertii Eggert’s sunflower S

Hydrastis canadensis goldenseal S-CE American water- Hydrocotyle americana E pennywort Juglans cinerea butternut T

Juncus brachycephalus small-headed rush S

Leavenworthia exigua var. exigua glade-cress S

Duck river Lesquerella densipila T bladderpod

Lesquerella globosa Short’s bladderpod E C

Lilium canadense Canada lily T

Lilium michiganense Michigan lily T

broadleaf Melanthium latifolium E bunchflower Alabama snow- Neviusia alabamensis T wreath

Panax quinquefolius American ginseng S-CE

large-leaved grass-of- Parnassia grandifolia S parnassus Perideridia americana thicket parsley E

Phlox bifida ssp. stellaria glade cleft phlox T

bearded rattlesnake- Prenanthes barbata S root white water- Ranunculus aquatilis var. diffusus E buttercup

Ribes missouriense Missouri gooseberry S

Sagittaria graminea grassleaf arrowhead T

Stellaria fontinalis water switchwort T limestone fame- Talinum calcaricum S flower

Harpeth River, Tennessee 27 Final Reconnaissance Report May 2012 State Federally Scientific Name Common Name Protected Protected

Birds

Accipiter striatus sharp-shinned hawk D No Status

Aqulia chrysaetos golden eagle T

Dendroica cerulean cerulean warbler D

Haliaeetus leucocephalus bald eagle D

Thryomanes bewickii Bewick’s wren E

Amphibians

Hemidactylium scutatum four-toed salamander D

Reptiles

Pituophis melanoleucus melanoleucus Northern pinesnake T

Mammals

Myotis grisescens gray bat E LE

Myotis sodalis Indiana bat E LE

Sorex longirostris southeastern shrew D

meadow jumping Zapus hudsonius D No Status mouse Fish

Etheostoma microlepidum smallscale darter D

Etheostoma tippecanoe tippecanoe darter D

Percina phoxocephala slenderhead darter D Ecological Systems

Carex lurida – Carex leptalea – Parnassia grandifolia – Highland Rim Rare, Not Juncus brachycephalus – (Xyris tennesseensis) Parnassia Seepage State Listed herbaceous vegetation Fen LE – Listed Endangered; LT – Listed Threatened; C – Candidate Species; S – Special Concern; E – Endangered; T – Threatened; D – Deemed in Need of Management; S-CE - Special Concern, Commercially Exploited

Harpeth River, Tennessee 28 Final Reconnaissance Report May 2012 5.4.9 Wetlands

The U.S. Fish and Wildlife Service National Wetlands Inventory identifies over 6,800 acres of potential wetlands scattered throughout the watershed. Table 3 identifies each type of wetland and the number of acres associated.

Table 3 - Wetland Types and Acres in the Harpeth River Watershed Type Acres Freshwater Emergent Wetlands 317.91 Freshwater Forested/Shrub Wetland 2,364.65 Freshwater Pond 2,000.83 Lake 710.77 Other 14.87 Riverine 1,410.69

5.4.10 Anthropological & Archaeological Considerations

The Harpeth River Watershed has seen the presence of human beings for thousands of years. All cultural periods (Paleoindian, Archaic, Woodland, Mississippian, and Historic) have been documented, represented by over 620 recorded archaeological sites. The watershed has long been attractive for settlement, utilizing the river itself (for commerce, food procurement, transportation, mills, and forges) and its fertile floodplains and terraces (for horticulture, agriculture, settlements, cities, and religious sites). Harpeth River State Park is a linear park created to connect several state historic, natural, and archaeological sites along the lower Harpeth River. The park includes an incised meander in the river known as the Narrows of the Harpeth and its associated Historic Civil Engineering Landmark, the Montgomery Bell Tunnel. The park also includes the Mound Bottom and Mace Bluff archaeological sites, the Newsom's Mill Historic Site, the Gossett Tract State Natural Area, and a section of land at Hidden Lakes.

The Mississippian Period (800 to 1500 Common Era (CE)), perhaps, saw the greatest prehistoric population within the Harpeth River Watershed, evidenced by large palisaded villages with several hundred or even thousands of residents, occupied for hundreds of years. This culture left behind numerous mounds and mound complexes that can still be seen on the Harpeth River watershed landscape today, with Mound Bottom as the most notable. The American Civil War was another notable time period for the Harpeth River Valley hosting several major battles, with the Franklin-Nashville campaign of strategic importance. Additionally, there are abandoned bridges dating to the late 1800’s with substructures that remain in place at this time. The modern decade has seen a major movement in preserving the history and land of these battles. The landscape, battlefield, homes utilized as field hospitals, plantations utilized as battlefield headquarters, have all been preserved and recorded on the National Register of Historic Places. Cultural history of the Harpeth River Watershed is rich and varied; it is a product of the natural environment. As part of which, it must be protected along with the abundant

Harpeth River, Tennessee 29 Final Reconnaissance Report May 2012 wildlife and ecosystems that made the watershed so attractive to humans throughout prehistory, history, and into modern times.

As aforementioned, Big Turnbull Creek, Harpeth River, Jones Creek, and the South Harpeth River are four streams within the Harpeth River Watershed that are listed on the Nationwide Rivers Inventory as “free-flowing rivers that are believed to possess one or more outstanding natural or cultural values.”

5.4.11 Population & Landuse Low to high intensity developments are scattered throughout the watershed. The upper and lower ends of the basin are more rural and sparsely populated (National Land Cover Database, 2006). Developed and urbanized areas within the basin include the cities of Brentwood (population 37,060), Fairview (7,720) and Franklin (population 62,487) in Williamson County; Bellevue in Metropolitan Davidson County; Kingston Springs (population 2,756) and Pegram (population 2,093) in Cheatham County; and Burns , White Bluff, Charlotte, and portions of the City of Dickson (population 14,538) in Dickson County. The watershed covers over 550,000 acres with primary land use types classified as forested and pastured areas. Other land use types include cultivated crops and developed areas. A map of the land cover data is shown below in Figure 11.

Figure 11 – Map showing Land Cover Data for the Harpeth River Watershed, from the USGS’s National Land Cover Dataset

Harpeth River, Tennessee 30 Final Reconnaissance Report May 2012 5.4.12 Inventory & Forecast of Hydrologic Conditions

A very large portion of the Harpeth River Watershed, while still primarily rural and suburban as a whole, lies in Williamson County, one of the fastest growing counties in the Nation. According the US Census Bureau, from 2000 to 2010, Williamson County’s population grew by 44.7%. In this same time period, Davidson County experienced a 10% population growth, Cheatham County experienced an 8.9% population growth, and Dickson County experienced a 15.1% population growth.

According to a report prepared by the Harpeth River Watershed Association (HRWA) in January 2009, in which the change in impervious area was analyzed from 2001 through 2008 by HUC 12 subwatershed, the Harpeth Basin saw increases in impervious areas of up to nearly 34% in some HUC 12 subwatersheds.

As Williamson County is also one of the wealthiest counties in the region, and due to these aforementioned growth trends, population is expected to continue to increase throughout the 50 year study period. As population and development continues, the increase in impervious areas and the alterations to the natural hydrology of the watershed will exacerbate both flooding and ecosystem issues in the Harpeth Basin.

Urbanization

Recent decades have seen significant development within the Harpeth River watershed, particularly in the populated areas of Franklin, Brentwood, and Bellevue. In addition to potential degradation of storm water quality (suspended solids, pollutants, temperature, etc.) resulting from the urbanization seen in the basin, there are hydrologic consequences that affect the magnitude, frequency, duration and velocity of flows in the stream.

Urbanization affects the magnitude of flow in a stream. In an undeveloped area, a portion of each rainfall event is infiltrated into the soils, transpired in vegetation, or evaporated from shallow depressions that hold water. As urbanization takes place, many of the available soils and plants are replaced by impervious surfaces that decrease the amount of infiltration and increase the magnitude of runoff from the rainfall. As a result, rainfall events that formerly produced within-bank flows or minor nuisance flooding now produce out-of-bank flows and damaging floods. This contributes to the increased frequency of flood damages incurred.

In an attempt to mitigate urbanization effects upon peak flood discharges, many communities, including Davidson and Williamson Counties, have developed storm water regulations that require storm water detention in new projects. The detention is intended to ensure that the design storm peak rate of discharge from the site does not exceed the pre-project condition. While this is helpful in some respects, the design storm has typically been below the 2% annual chance exceedence event, and has only in more recent years been increased to the 1% event in some jurisdictions. For projects completed before the change in regulations, storm water runs off unmitigated during larger storm events. Additionally, there are unintended consequences associated with storm water detention that may contribute to the current conditions within the Harpeth River Watershed. One such consequence is that

Harpeth River, Tennessee 31 Final Reconnaissance Report May 2012 by detaining storm water and releasing it at a uniform rate designed to stay at, or below, the design peak flow, the peak rate of discharge is extended for a longer period of time than would be experienced during natural conditions. This means that areas that are inundated during the peak flow may be inundated for a longer period of time, which could increase damages. If the flow rate during the design storm results in damaging velocities, then the damaging velocity is also extended for a longer duration. This could result in further stream bank erosion, stream bed scour or bridge scour.

Flood History

The Harpeth River Watershed has a well documented history of repeated, large flood events. Table 4 and Table 5, which follow, rank the historical floods at both the Bellevue and Kingston Springs gages on the main stem of the river. The Little Harpeth River, a tributary of the Harpeth River, has had flooding problems for many years. Major floods occurred on the Little Harpeth River in 1929, 1948, 1955, 1960, 1962, 1973, 1975, and 1979 (USACE 1991).

March 1975 saw 7-9 inches of rainfall in the Harpeth River Basin and brought about some of the Harpeth Basin’s more recent major flooding. Photographs from this flood event are shown below in Figure 12 and Figure 13. Damages were recorded as follows, according to a 1975 Flood Damage Survey:

• Newsome Station Area – $47,000, with six homes, a racetrack and roads damaged as noted in the report. ($190,350 in 2011 dollars) • Bellevue – $11,900, mostly residential with some municipal and roads. ($48,195 in 2011 dollars) • Franklin – $3,588,800, severe damage; homes in the Ewingville, Harpeth Meadows and Rebel Meadows areas; damaged boot factory accounted for 2/3 of the City’s total loss; flooded businesses along highways 431 and 31. ($14,534,640 in 2011 dollars) • Brentwood (Little Harpeth River) – $10,500, damage mostly from local drainage problems. ($42,525 in 2011 dollars)

Table 4 – Ranked Historical Floods near Kingston Springs, Tennessee

Harpeth River near Kingston Springs Date Peak Discharge (cfs) Stage (ft) Elevation (ft) May 2010 Gage Destroyed 492.97 (HWM) January 7, 1946 60,000 32.2 480.2 February 27, 1962 47,800 29.5 477.6 February 14, 1948 47,000 29.0 477.0 March 1902 Unknown 28.9 476.9 March 13, 1975 44,500 28.8 476.8 March 22, 1955 41,500 28.0 476.0 January 1, 1945 39,900 27.0 475.0 January 29, 1957 33,000 25.7 473.7 February 3, 1932 34,500 25.3 473.3 March 13, 1927 33,500 25.0 473.0

Harpeth River, Tennessee 32 Final Reconnaissance Report May 2012

Figure 12 - Businesses along US 431 in Franklin, Tennessee, 13 March 1975

Figure 13 - Flooding in the Harpeth Meadows subdivision in Williamson County, 13 March 1975

Harpeth River, Tennessee 33 Final Reconnaissance Report May 2012 In May of 2010, Middle Tennessee was rocked with a storm event of unprecedented magnitude that caused record flooding across much of the region, including the Harpeth River Watershed. The watershed saw the highest two-day rainfall totals in Middle Tennessee from the extreme event at almost 18”. Table 6 shows the severity of the May 2010 flooding, as flood waters reached unprecedented stages during the event. Although the gages were destroyed in the May event, it is estimated that the peak discharges during this flood more than doubled the peaks of the next highest flood at Kingston Springs and Bellevue. Flooding on the Harpeth River and its tributaries in the May 2010 event caused 4 fatalities and an estimated $482 Million in direct economic damages. Some of the fatalities seen throughout Tennessee during the storm were the result of ignored warnings and attempts to drive through running water. Figure 14, below, shows flooding in the Harpeth Basin in the May 2010 event. Property damage during the flood included numerous homes in Cheatham, Davidson, and Williamson Counties; damaged roads; and destroyed railroad crossings. It is noteworthy that Davidson County’s minimum standard is that homes be constructed four feet above the base flood elevation, and that even then some of those homes had four to six feet, or more, of water inside the living areas. In some locations the high water marks for the storm exceeded the Flood Insurance Report (FIS) 500-year profile elevation by as much as six feet. Add to this the unexpected magnitude of rainfall and the rapid rise of the river during this storm and the result is an extreme flash flood on a relatively large stream. Warning time for this event was minimal, resulting in severe property and infrastructure damage. People had little time to escape and almost no time to evacuate belongings.

During the flood, mature trees and vegetation were uprooted throughout the watershed adding to the severe erosion. Portions of the river also experienced landslides that caused debris and vegetation to accumulate in river (HRWA 2011). The accumulation of debris causes concerns for potential flooding during rain events.

Table 5 – Ranked Historical Floods at Bellevue, Tennessee Harpeth River at Bellevue Date Peak Discharge (cfs) Stage (ft) Elevation (ft) May 2010 Gage Destroyed 573.73 (HWM) February 13, 1948 40,000 24.3 565.4 March 13, 1975 39,600 24.3 565.3 March 23, 1939 Unknown 22.3 563.3 March 22, 1955 28.900 22.2 563.2 March 13, 1927 Unknown 21.7 562.7 February 27, 1962 23.700 21.0 562.0 April 11, 1927 Unknown 20.6 561.6 December 25, 1926 Unknown 20.3 561.3 December 21, 1926 Unknown 20.2 561.2 February 18, 1956 20,500 20.2 561.2

Harpeth River, Tennessee 34 Final Reconnaissance Report May 2012 Table 6 – Record or Near Record Flood Levels set during the May 1-2 flood event (USACE 2012) May 2010 Flood Date of Old Flood Location Old Record Crest Record Stage

Harpeth River near Kingston 46.00’ 32.2’ January 7, 1946 20´ Springs

Harpeth River at Bellevue 33.23’ 24.3’ February 13, 1948 20´

Harpeth River at Franklin 35.11’ 33.6’ March 13, 1975 30´

Figure 14 – Flooding in downtown Franklin, Tennessee, during the May 2010 flood event.

5.4.13 Water Supply

The nation’s fresh water resources are both essential to human existence as well as threatened by the presence of humans. Although water supply may not be an issue at the forefront within most of the Harpeth River Watershed at the time of this writing, it is becoming an increasingly important and controversial topic across the region. In Franklin, the largest population center in the watershed, use of the Harpeth River as a water source is a significant issue and should be considered in future watershed planning.

According to a TDEC report with a revision date of March, 2007, there are two communities using groundwater for water supply in the watershed: Dickson Water District and Nolensville-College Grove. According to this report, there are three utilities with surface water intakes in the Watershed. These are Second South Cheatham Utility District, Turnbull Utility District, and Franklin Water Department. Most of these utility districts are interconnected and will use both surface and ground water.

Harpeth River, Tennessee 35 Final Reconnaissance Report May 2012 5.4.14 Stormwater Runoff, Regulations, & Design Standards

There are several Municipal Separate Storm Sewer Systems (MS4) within the Harpeth River Watershed. MS4’s are cities and counties identified by the state as being of sufficient size and impact to affect stormwater quality. These communities have permits to discharge stormwater under the National Pollutant Discharge Elimination System. The requirements of their permits are above the requirements for a general permit for the discharge of construction storm water and include requirements for new local regulations, stormwater quality monitoring and the implementation of best management practices (BMP’s) within the community to maintain or improve the quality of stormwater runoff. Additionally, most communities participate in the National Flood Insurance Program and have adopted the minimum regulations required by the program. Several of the communities have enhanced regulations that provide more restrictive control of floodplain development, and some even prohibit any development within the regulatory floodplain.

5.4.15 Climate Variability

The climate of the Southeastern United States is generally warm and wet, with mild winters and high humidity (USGCRP, 2009). Over the past century (1901-2008), the average annual temperature did not noticeably change, however, since 1970 (1970-2008), the annual average temperature during the winter months has risen approximately 2°F. Since the mid-1970’s, moderate to severe spring droughts have increased by 12%; and summer droughts, which have increased by 14%, now extend into the fall months when precipitation used to increase (USGCRP, 2009).

Climate models forecast that increased warming will continue through the end of this century for all seasons with the greatest temperature increases in the summer months across the Southeast (USGCRP, 2009). Average temperatures are projected to rise between 4.5-9 °F by the 2080s (USGCRP, 2009). Very hot days (>90 °F) are expected to increase from approximately 60 currently to 120 days by the end of this century (USGCRP, 2009). Because higher temperatures lead to more evaporation, drier soils, and water loss from streams, the frequency, duration, and intensity of droughts are likely to continue to increase (USGCRP, 2009). Increased air and water temperatures can be expected to cause heat stress for people, terrestrial, and aquatic ecosystems from now through the end of the century within the Harpeth River watershed.

As the frequency and duration of drought increases, water availability for people and the aquatic ecosystem decreases. This is aggravated by the increase in impervious surface and loss of rainfall infiltration due to urbanization, which in turn can reduce base flow in a stream.

Under this forecast of increasing temperatures, warmer water holds less dissolved oxygen; therefore, it is expected that dissolved oxygen in streams, lakes, and rivers will decline leading to fish kills and loss of other aquatic species (USGCRP, 2009). Other affects may include new distribution patterns for native plants and animals and invasive species displacing native species (USGCRP, 2009). Under this new distribution pattern, it is possible that the local loss of many state and federally listed species could occur (USGCRP, 2009).

Harpeth River, Tennessee 36 Final Reconnaissance Report May 2012 One of the clearest precipitation trends in the United States is the increasing frequency and intensity of heavy downpours (USGCRP, 2009). Since 1901, the average fall precipitation in the Southeast has increased by 30% with an increase in heavy downpours (USGCRP, 2009). For states in the region like Tennessee, precipitation is projected to increase in winter and spring, and to become more intense throughout the year (USGCRP, 2009).

Heavy downpours increase storm water runoff resulting in increased soil erosion, increased sediment runoff into streams, and increased stream turbidity that reduce stream and aquatic habitat quality (USGAO, 2007). Large amounts of suspended sediments can settle on fish spawning beds and freshwater mussels that can disrupt feeding, migration, and reproduction (USGAO, 2007). Under this forecast, the number and duration of heavy rain events is anticipated to increase (USGAO, 2007). Additionally, the increased runoff can carry petroleum, oils and lubricants, chemicals and other man- made pollutants into the stream further degrading water quality.

5.5 Planning Objectives

The national objectives of National Economic Development (NED) and National Ecosystem Restoration (NER) are general statements and not specific enough for direct use in plan formulation. The water and related land resource problems and opportunities identified in this study are stated as specific planning objectives to provide focus for the formulation of alternatives. These planning objectives reflect the problems and opportunities and represent desired positive changes in the without project conditions. The planning objectives are specified as follows:

• To reduce the loss of life risk associated with flooding in the Harpeth River Watershed for the 50 year period of study. • To reduce economic flood damages throughout the Harpeth River Watershed for the 50 year period of study. • To reduce sediment loading in the Harpeth River and its detrimental impacts to the aquatic ecosystem by stopping erosion at sites throughout the Harpeth River Watershed, such as the site at Burns Park in Kingston Springs, Tennessee through the 50 year period of study. • To improve the habitats of both endemic and endangered flora and fauna in the Harpeth River Watershed through the 50 year period of study. • To restore aquatic and riparian ecosystems throughout the Harpeth River Watershed through the 50 year period of study.

5.6 Planning Constraints

Unlike planning objectives that represent desired positive changes, planning constraints represent restrictions that should not be violated. The planning constraints identified in this study are as follows:

• Compliance with county and municipal land use plans. • Compliance with applicable Federal, State, and local statues, regulations, and executive orders.

Harpeth River, Tennessee 37 Final Reconnaissance Report May 2012 5.7 Measures to Address Identified Planning Objectives

A management measure is a feature or activity at a site, which addresses one or more of the planning objectives. A wide variety of measures were considered, some of which were found to be infeasible due to technical, economic, or environmental constraints. Each measure was assessed and a determination made regarding whether it should be retained in the formulation of alternative plans. The descriptions and results of the evaluations of the measures considered in this study are presented below:

1) Non-Structural measures considered to address the identified flooding issues within the Harpeth River Watershed include floodproofing, raising structures in place, buyouts, and relocations. Each non- structural measure has areas where it is more applicable. Floodproofing is generally more effective for commercial and industrial structures, and less effective for residential structures. Raising structures in place is generally more effective for residential structures, except for residential structures that are slab- on-grade structures.

In this analysis, raising residential structures in place and buyouts or relocations are determined to merit further consideration due to the scattered nature of residences that fall within floodplains. In many cases, where regional detention or structural measures are not practical, nonstructural measures are appropriate to reduce the flood risk for loss of life and property.

Nonstructural measures also include the development of flood warning systems and flood preparedness plans. A planning assistance to states study was begun with Metro Nashville after the May 2010 flood to study the streams in Nashville and develop action plans for future flood events. This study has proven highly successful, and similar studies are recommended, as a minimum, for other counties and cities.

2) Structural measures are those that impact the flow of water. Structural measures include levees, floodwalls, dams, dry dams, various detention structures, and cutoff channels. As aforementioned, there are opportunities in the Harpeth River Watershed for levees and floodwalls, as well as regional detention structures. There is also the opportunity for a high flow diversion channel on the main stem of the Harpeth River, as well as one on the Little Harpeth River in Brentwood, as detailed in previous studies. The scattered nature of the at-risk structures in the watershed and the locations of the rural areas of the watershed make regional high flow detention measures ideal for managing flood risk throughout the majority of the basin.

3) Ecosystem Restoration measures considered in this analysis are intended to protect and restore precious aquatic habitat for a wide variety of fish and wildlife in the Harpeth Basin, including those that are federally listed as endangered and those that are endemic to the Harpeth River Basin.

After the May 2010 flood event, there is a definite need for riparian zone restoration as well. Tree and vegetative plantings and restoration are measures that would be beneficial to address this issue. Riparian zone restoration is crucial to maintaining and effectively restoring aquatic habitat. Riparian zones provide shelter, shade, and filtration, among other benefits, to the aquatic habitat.

Harpeth River, Tennessee 38 Final Reconnaissance Report May 2012 The restoration of wetlands that are threatened by agricultural and urban or suburban land uses also provide many benefits to the riverine aquatic habitat, and are another type of aquatic habitat.

4) Recreational Opportunities that would be of great benefit in the Harpeth River Watershed, as well as garner support from stakeholders, include improving recreational access and recreational features throughout the watershed. With the existing recreational significance and public interest throughout the Harpeth River Watershed, adding canoe access points or greenways, for example, would be strong features for any project in the region.

5.8 Preliminary Plans

Preliminary plans are comprised of one or more management measures that survive the initial screening. The descriptions and results of the evaluations of the preliminary plans considered in this study are presented below:

1) Preliminary plans that may not be considered in further analysis:

• Results from preliminary bridge widening analysis in the modeled portion of the stream (downstream of Williamson County) indicate a lack of benefits, and that these alternatives would not be economically justifiable. This does not pertain to the Highway 100 Bridge, which could be economically justifiable, and should be further studied at the feasibility level. • Certain levee/floodwall combinations that only protect from very infrequent flood events will not be economically justifiable. • The use of riprap toes and riprap armoring are preferably avoided for streambank stabilization measures, as riprap could be detrimental to the environment. Other stabilization measures should be considered, and when possible prioritized above riprap.

2) Preliminary plans for further consideration:

The following plans for further consideration at a feasibility level of study could be pursued as either a comprehensive watershed study that analyzed both flood risk management and ecosystem restoration alternatives, or one or more CAP feasibility studies.

• No Action. This involves no action by the Corps of Engineers beyond what is already occurring.

• Structural FRM Alternatives. Structural measures that would be considered for feasibility level analysis include, but are not limited to, bridge modifications, channel widening, cutoffs, levees and floodwalls, and regional/dry detention.

Preliminary analysis of a dry dam on the Harpeth River upstream of Franklin, Tennessee, indicates that there is great potential for this alternative to provide flood risk management benefits in the basin.

In addition to this regional detention measure, preliminary screening suggests that other regional detention measures on tributaries of the Harpeth throughout the basin would be

Harpeth River, Tennessee 39 Final Reconnaissance Report May 2012 appropriate for further investigation in the feasibility phase of study. Potentially a combination of regional detention structures would yield the greatest contribution to the NED goal.

• Nonstructural FRM Alternatives. Several nonstructural flood risk management alternatives warrant further study at the feasibility level. In many cases, especially for structures that are scattered, nonstructural measures appear to be the most appropriate. These measures could include, but are not limited to, wet floodproofing, floodproofing, ring levees, raising in place, evacuations, and relocations. The appropriate nonstructural measure for each structure or area would be determined in the feasibility level of study.

• Flood Preparedness Studies. The flood preparedness study that was initiated after the May 2010 flood and is currently ongoing has helped Nashville develop comprehensive action plans and emergency response strategies for future flood events. This sort of emergency action planning and preparedness for future flood events, particularly flood warning systems, would prove to be very beneficial for both the reduction in risk to human life and property.

• Erosion Control and Streambank Stabilization. Erosion is apparent in many areas throughout the Harpeth Basin, including, but not limited to, City and Burns Parks in Kingston Springs, Tennessee. Erosion from loss of riparian zones and wetlands causes sedimentation and other contaminants to enter streams and rivers. Sedimentation degrades and threatens aquatic habitat for a variety of species throughout the watershed. The habitat of the tan riffleshell, the federally endangered mussel historically found in the Harpeth Basin, as mentioned previously, prefers a habitat consisting of coarse substrate in riffle areas in small to medium rivers and is adversely impacted by impoundments, siltation, and pollution (USFWS 1984). Other aquatic species discussed in this report also depend on specific habitat conditions to thrive. Restoring riparian zones and wetlands to help reduce the amount of sedimentation and contaminants entering stream reaches would be beneficial to the quality of the aquatic ecosystem. Erosion in the watershed is also impacting public lands and cultural and archaeological resources.

Measures that have been proposed that warrant further consideration at the feasibility level of study include in-stream features such as foreshore dikes and bendway weirs. Other measures would include, but are not limited to, bio-engineering.

• Riparian Zone Restoration. After the May 2010 flood event, the loss of riparian zones in areas of the Harpeth basin has became a much more recognized issue, as the May 2010 event further exacerbated the previous riparian zone issues greatly. There are many areas in the watershed where there were previously significant riparian areas, which provide many environmental and erosion benefits. Since the May 2010 flood, numerous areas of streambank are without significant buffers of vegetation. Riparian zones provide numerous benefits to aquatic life and their habitats; restoring these buffers would help reduce the amount of contaminants and would provide benefits to aquatic species and their habitats living within the watershed.

3) Alternative Implementation Authorities

Harpeth River, Tennessee 40 Final Reconnaissance Report May 2012 Authorization for flood risk management and/or ecosystem restoration projects of limited cost and complexity could be implemented by the Corps under the Continuing Authorities Program (CAP). CAP authorities provide for planning, designing, and constructing projects of limited scope and complexity. For larger, comprehensive implementation, specific Congressional authority would be required for implementation.

5.9 Conclusions from the Preliminary Screening

The preliminary screening indicates that there are many alternatives that address water resource problems in the Harpeth River Watershed, and promote both NED and NER objectives. The potential magnitude and types of benefits from the proposed actions would help significantly reduce flood damages in the Harpeth Basin, where there were an estimated $480 Million in direct economic damages and four lives lost in the May 2010 flood event. Continuing with the project would also have ecosystem restoration benefits that contribute to the NER objectives by restoring the aquatic habitat to its natural state.

There is interest in further study of both flood risk management and ecosystem restoration alternatives. Due to the uncertain availability of a nonfederal sponsor, one of several paths forward would be appropriate for the future study of the Harpeth River Watershed:

1) Ideally, the Corps would continue forward with a comprehensive Investigations study on the entire watershed, to include both ecosystem restoration and flood risk management components. This would address both the known flooding issues in the basin, as well as potential ecosystem restoration sites, such as the Burns and City Parks sites in Kingston Springs. The drawback to this path forward is finding a non-federal sponsor or sponsors that would partner with the Corps on a comprehensive watershed study. The size of the watershed and that it covers many different political jurisdictions raises concerns in finding a local sponsor. 2) The Corps could move forward with an Investigations study or studies that would address specific sites and issues, such as solely FRM, rather than looking at the basin in its entirety. These could be effective, but limit the scope to one issue in a basin that has needs in both Flood Risk Management and Ecosystem Restoration. Specific partners would be sought for specific problems and issues. 3) Another effective path forward would be continuing forward into feasibility with multiple smaller CAP projects with several sponsors. These could be both Section 205 and Section 206 projects to address relatively minor flood risk management needs and ecosystem restoration needs throughout the basin.

The comprehensive Investigations study is the ideal vehicle for addressing as many of the issues identified in this report as possible. Not only are there typically higher ceilings on the cost of the final project, allowing for more actual implementation in a basin with many needs, but a comprehensive Investigations study would also be able to address all of the problems that the Corps has found interest

Harpeth River, Tennessee 41 Final Reconnaissance Report May 2012 in within the basin. The downside is a higher study cost and thus more difficulty obtaining Corps and sponsor funding.

Smaller, more focused Investigations studies or CAP studies are also effective vehicles for carrying out beneficial projects within the basin, however they would not be able to address as many issues due to scope and budget limitations. Therefore, the goal is to execute a comprehensive feasibility study to address both FRM and ER throughout the watershed, however ultimately the path forward will be determined by the goals of a nonfederal sponsor.

Costs of the alternatives for both flood risk management and ecosystem restoration will be developed in detail in the feasibility phase of study.

5.10 Establishment of a Plan Formulation Rationale The conclusions from this preliminary screening form the basis for the next iteration of the planning steps that will be conducted in the feasibility phase. The likely array of alternatives that will be considered in the next iteration include no action, regional detention measures, both structural and non-structural flood risk management measures, ecosystem restoration measures, and erosion control measures. Future screening and reformulation will be based on effectiveness, economic, feasibility, and policy compliance factors, all which ensure that the NED and NER plans are implemented in the basin.

5.11 Environmental Impacts of Proposed Actions Alternatives developed in the feasibility phase of study will undergo necessary environmental policy requirements, and the appropriate level of environmental assessment will be completed during the feasibility phase. There are known endangered species in the basin, and proper avoidance and mitigation measures will be performed where necessary for any alternatives proposed for implementation.

6.0 Federal Interest Both flood risk management and ecosystem restoration are primary Corps civil works missions with high budget priorities, and preliminary investigations have shown that there is a federal interest in pursuing both flood risk management and ecosystem restoration measures. The determination of federal interest in flood risk management is based on the level of damages documented and their recurring nature. In the wake of the May 2010 flood, it is evident that there is an unacceptable risk to human life and property in the Harpeth basin, along with much of Middle Tennessee. With four fatalities and approximately $480 Million in direct economic damages in the Harpeth basin alone, further study of structural and nonstructural flood risk management alternatives is imperative. Cursory reviews of potential measures, both structural and nonstructural, have demonstrated their plausibility of implementation.

Opportunities for ecosystem restoration in the Harpeth Basin, which sustain and improve habitat to nationally significant species, also warrant further study. Preliminary analysis of ecosystem restoration

Harpeth River, Tennessee 42 Final Reconnaissance Report May 2012 measures show that the aquatic ecosystem could be improved for threatened and endangered as well as endemic species.

Proposed flood risk management measures and ecosystem restoration measures are both likely to produce outputs that outweigh their costs, thus the Nashville District recommends further study of these flood risk management and ecosystem restoration opportunities in the Harpeth Basin. These opportunities and proposed measures laid out in this document will be optimized by an incremental analysis during the feasibility study.

7.0 Preliminary Financial Analysis To continue to feasibility, a local sponsor will be required to provide 50 percent of the cost of the feasibility phase for both Investigations and CAP studies. Letters of Intent from potential local sponsors stating a willingness to purse a comprehensive watershed study and to share in its cost are included as Appendix C. The sponsors who have submitted letters of intent understand the cost sharing requirements of the feasibility study.

8.0 Assumptions, Expectations, and Quality Objectives a. Feasibility Phase Assumptions: The following critical assumptions will provide a basis for the feasibility study:

• Multiple sponsors will come together to pursue a regional approach to flood risk management. • Both sponsor and federal funding will be available, and an investigations study will be initiated to be completed in 3 years and with no more than $3 million. • Without a project, flood damages and impacts will continue to occur at a potentially increasing frequency due to both increasing runoff from development as well as climate variability. • Updated surveys and more detailed economic damages and benefits would be conducted during the feasibility level.

b. Policy Exceptions and Streamlining Initiatives: The study will be conducted in accordance with the Principles and Guidelines and the Corps of Engineers regulations. No policy exceptions have been identified at this time. The current streamlining initiative from the Deputy Commanding General of Civil and Emergency Operations (DCG-CEO) is to have feasibility studies last a maximum of 3 years, cost a maximum of $3 million, and undergo 3 levels of review. With the wealth of existing data and the multi- agency interest in the watershed that already exists, the Nashville District would be able to comply with this “3x3x3” mandate. This concept of streamlining the feasibility study would provide a more timely and efficient move towards implementation of FRM and Ecosystem Restoration measures in the watershed.

c. Quality Objectives: Feasibility Phase studies will be accomplished to meet the following quality objectives:

1) Information developed will be adequate for the local sponsor to make appropriate water resource planning decisions.

Harpeth River, Tennessee 43 Final Reconnaissance Report May 2012 2) Primary objectives of either flood risk management or ecosystem restoration will be met.

9.0 Feasibility Phase Milestones

Table 7 - Tentative Feasibility Phase Schedule Description Duration (mo) Cumulative (mo) Initiate Study 0 0 Public Workshop/Scoping 2 2 Feasibility Scoping Meeting (FSM) 11 13 Alternative Formulation Briefing (AFB) 9 22 Draft Feasibility Report 3 25 Final Public Meeting 1 26 Final Report to LRD 3 29

10.0 Feasibility Phase Cost Estimate Feasibility phase cost estimates will be produced once a sponsor is identified and a specific scope of work is developed. However, costs will be kept within the $3 million limit seen in the new feasibility study streamlining initiative. The PDT does not believe that completing the feasibility phase within $3 million will be an issue, given the availability of data on the watershed currently. For a smaller CAP study, the study costs would more than likely be significantly less than $3 million.

11.0 Views of Other Resource Agencies Because of the funding and time constraints of the reconnaissance phase, only limited and informal coordination has been conducted with other resource agencies. Views that have been expressed are as follows: a. Reducing the risk of flooding to human life and property. b. Protection of fish and wildlife, especially those that are federally listed as threatened or endangered, and their habitat.

12.0 Potential Issues Affecting Initiation of Feasibility Phase a. Continuation of this study into the cost-shared feasibility phase is contingent upon an executed FCSA. Issues that could impact the initiation of the feasibility phase primarily revolve around the ability to come to an agreement with a willing sponsor or a group of sponsors. Not only is the availability of sponsor funding a potential issue, the availability of federal funding, required to begin a feasibility study, is uncertain with the current budgetary climate. b. The schedule for signing the Feasibility Cost Sharing Agreement (FCSA) is August 2012

Harpeth River, Tennessee 44 Final Reconnaissance Report May 2012 13.0 Recommendations Based on the repeated historic flooding described in this report and the fatalities and devastating damages from the May 2010 flood of record, I recommend the Harpeth River study proceed into the feasibility phase to further investigate the federal interest in solving flood risk management problems, realizing known ecosystem opportunities, and potentially addressing other water and related land problems and opportunities basin-wide.

James A. DeLapp Lieutenant Colonel Corps of Engineers District Engineer

Harpeth River, Tennessee 45 Final Reconnaissance Report May 2012