Mud Creek Watershed Restoration Plan

Watershed Restoration Plan for the Mud Creek Watershed

Mud Creek Watershed Restoration Council January 2003 Revised April 2003

TABLE OF CONTENTS Table of Contents ........................................................................................................................... i List of Tables ................................................................................................................................. ii List of Figures................................................................................................................................ ii Executive Summary ..................................................................................................................... iv Section 1: Project Overview........................................................................................................ 1 1.1 1.2 1.3 1.4 1.5

Introduction......................................................................................................................... 1 The Mud Creek Watershed Restoration Council ................................................................ 2 NC Division of Water Quality Watershed Assessment and Restoration Project................ 2 NC Wetlands Restoration Program Local Watershed Planning ......................................... 3 Tennessee Valley Authority Integrated Pollutant Source Identification ............................ 3

Section 2: Mud Creek Watershed Characterization ................................................................ 4 2.1 2.2 2.3 2.4 2.5 2.5.1 2.5.2 2.5.3 2.5.4 2.5.5 2.6 2.6.1 2.6.2 2.6.3 2.6.4 2.6.5 2.6.6 2.6.7 2.6.8 2.6.9

Introduction......................................................................................................................... 4 Hydrology and Sub-Watershed Delineation ....................................................................... 4 Soils..................................................................................................................................... 6 Land Use/Land Cover in the Mud Creek Watershed.......................................................... 6 Water Quality and Stream Health ....................................................................................... 9 General Conclusions of WARP Assessment.................................................................... 9 DWQ Use Support Ratings ........................................................................................... 10 DWQ’s Watershed Assessment and Restoration Project (WARP) ............................... 12 Volunteer Water Information Network ......................................................................... 15 Channel and Riparian Buffer Condition....................................................................... 16 Local Water Quality Initiatives......................................................................................... 19 Local Environmental Ordinances ................................................................................. 19 Land Use Planning and Zoning .................................................................................... 20 State Stormwater Regulations....................................................................................... 21 Environmental and Conservation Organization (ECO) ............................................... 21 Volunteer Water Information Network ......................................................................... 22 Southside Development Initiative ................................................................................. 22 Apple Country Greenwy Commission........................................................................... 23 Carolina Mountain Land Conservancy ........................................................................ 23 French Broad Watershed Training Center ................................................................... 24

Section 3: Recommendations .................................................................................................... 25 3.1 Stormwater........................................................................................................................ 26 3.1.1 Overview ....................................................................................................................... 26 3.1.2 Strategies to minimize impacts of stormwater runoff from future development ........... 30 3.1.3 Strategies to reduce impacts of stormwater runoff from existing development............ 32 3.2 Agricultural Non Point Source Pollution.......................................................................... 35 3.2.1 Overview ....................................................................................................................... 35 Table of Contents

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3.2.2 Strategies to Control Agricultural Nonpoint Source Pollution .................................... 37 3.3 Habitat Degradation .......................................................................................................... 40 3.3.1 Overview ....................................................................................................................... 40 3.3.2 Strategies to Address Habitat Degradation.................................................................. 41 3.4 Upland Sources of Sedimentation..................................................................................... 44 3.4.1 Overview ....................................................................................................................... 44 3.4.2 Strategies to Address Upland Sources of Sedimentation.............................................. 46 Section 4: Next Steps.................................................................................................................. 49 4.1 4.2 4.3 4.4 4.5 4.6

Present Watershed Restoration Plan to the Community ................................................... 49 Formalize Watershed Council........................................................................................... 49 Hire Watershed Coordinator ............................................................................................. 49 Prioritize Recommendations............................................................................................. 49 Set Measurable Watershed Improvement Goals............................................................... 49 Secure Grants to Implement Projects................................................................................ 50

References.................................................................................................................................... 51 Appendix A .................................................................................................................................. 52 Appendix B .................................................................................................................................. 53 LIST OF TABLES Table 2.1: Table 2.2. Table 2.3: Table 2.4: Table 3.1: Table 3.2:

Summary of area, stream miles and slope by subwatershed. ....................................... 5 Percentage of subwatershed area by land use/cover..................................................... 7 Channelization and Buffers in the Mud Creek watershed .......................................... 18 Summary of Zoning in the Mud Creek watershed...................................................... 21 Existing Stormwater Management Ordinances in the Mud Creek watershed............ 29 Estimated sediment loading rates in tons/acre for land uses in the Mud Creek watershed. ................................................................................................................... 45 LIST OF FIGURES

Figure 1.1: Figure 2.1: Figure 2.2: Figure 2.3: Figure 2.4: Figure 2.5: Figure 2.6: Figure 2.7:

Map of the Mud Creek Watershed. ............................................................................ 1 Streams in the Mud Creek Watershed........................................................................ 4 Subwatersheds in the Mud Creek Watershed............................................................. 5 Generalized Land Use/Land Cover Patterns in the Mud Creek Watershed ............... 8 Use Classifications for streams in the Mud Creek Watershed ................................. 10 Use-support Ratings for streams in the Mud Creek Watershed ............................... 11 WARP Biological Monitoring Sites......................................................................... 12 Apple orchards and benthic macroinvertebrate communities in the Clear Creek and Devils Fork Subwatersheds..................................................... 13 Figure 2.8: Location of WARP water chemistry sampling sites. ............................................... 14 Table of Contents

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Figure 2.9: VWIN monitoring sites in the Mud Creek Watershed. ............................................ 15 Figure 2.10: Map of Hendersonville showing Mud Creek prior to channelization. ..................... 17 Figure 3.1: Stream vulnerability rating based on percent impervious cover in the Mud Creek Watershed – by subwatershed................................................................ 27 Figure 3.2: Existing wetlands and areas with hydric soils in the Mud Creek Watershed........... 28 Figure 3.3: Flooding at Hendersonville’s Southside, just one of many areas of chronic flooding exacerbated by floodplain development and impervious cover............................... 29 Figure 3.4: Agricultural land uses in the Mud Creek Watershed. .............................................. 35 Figure 3.5: Cattle with direct access to Mud Creek.................................................................... 36 Figure 3.6: Cattle access points to streams in the Mud Creek Watershed.................................. 36 Figure 3.7: Eroding streambanks cause sediment to fill stream channels impacting aquatic habitat....................................................................................................................... 40 Figure 3.8: Site of Clear Creek stream restoration project ......................................................... 42 Figure 3.9: Runoff from gravel driveway in the upper Mud Creek watershed........................... 44 Figure 3.10: Estimated annual sediment load from land uses in the Mud Creek watershed ....... 45 Figure 3.11: Number of building permits issued for new residential units in Henderson County 1996-2002 ................................................................................................................ 46

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EXECUTIVE SUMMARY For the past three years, local stakeholders and state and federal resource managers have worked together to gather data and outline a plan to restore the Mud Creek watershed. This document represents the culmination of efforts undertaken by these partners to evaluate all possible sources and causes of water quality degradation and recommend a comprehensive set of strategies for addressing these problems. Section 1 presents a brief overview of the project. In 2000, Land of Sky Regional Council of Governments convened local stakeholders in the Mud Creek watershed to develop a plan for addressing water quality problems in the watershed. At that same time, the Division of Water Quality initiated an independent study to identify causes and sources of impairment in the Mud Creek and two of its tributaries, Bat Fork and Clear Creek. These streams are on the North Carolina 303(d) List of Impaired Waterbodies. Concurrently, the NC Wetlands Restoration Program was interested in identifying potential stream and wetland restoration projects in the Mud Creek watershed and agreed to collect additional stream and watershed data through a partnership with the Tennessee Valley Authority to supplement efforts already underway in the watershed. Section 2 summarizes current conditions in the Mud Creek watershed including land use, water quality, channel and buffer conditions, habitat and wetlands. The Mud Creek watershed is 113 mi2 comprising approximately one-third of Henderson County’s land area. There are three municipalities in the watershed: Hendersonville, Flat Rock and Laurel Park. Forty-five percent of the Mud Creek watershed is forested, 25 percent is residential, commercial or industrial, and 23 percent is agricultural. The Mud Creek watershed has roughly 10% impervious cover, however, the percent of imperviousness varies greatly throughout the watershed with some areas far exceeding the 10% threshold where declines in water quality and aquatic communities are noted. Without appropriate water quality protection measures, increasing urbanization in the watershed will further exacerbate existing water quality problems. The Volunteer Water Information Network rates many streams in the Mud Creek watershed as below average and poor due to nutrient enrichment, turbidity and high metals concentrations. A comprehensive watershed assessment conducted by the NC Division of Water Quality (DWQ) in 2000-2002 indicates that biological communities in the Mud Creek watershed are impacted by a number of factors including toxicants from agriculture and urban sources, scour from high stormflow volumes, poor in-stream habitat, and a lack of tributaries with healthy biological communities. In addition, DWQ monitoring showed that several streams violated the state standards for fecal coliform bacteria levels. Historic practices such as channelizing streams, clearing streamside vegetation and draining and filling wetlands for agriculture and suburban development are prevalent across the watershed. Because of these practices, the quality and distribution of adequate riparian buffers in the Mud Creek watershed are insufficient to protect water quality and promote good aquatic habitat. In addition, these practices exacerbate streambank erosion, increase sedimentation and increase the volume and velocity of stormwater runoff. Pesticides from apple orchards and row crops likely degrade the biological communities of streams in the Clear Creek and Devils Fork area; both current and past use pesticides may play a Executive Summary

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role in stream degradation. Past use pesticides, such as DDT and chlordane, were widely used in agriculture and residential areas. In addition, row crop pesticides likely impact biological communities in upper Mud Creek. Nutrient enrichment is evident in the Mud Creek watershed and possible nutrient sources include cattle waste, straight pipes, failing septic systems and runoff from lawns, gardens, golf courses and crop land. In urban streams, the combined factors of toxicants such as metals, organic pollutants, and pesticides and scouring energy from high stormflow volumes severely limit biological communities. Increasing turbidity levels noted in streams in the Mud Creek watershed are probably the result of escalating land-disturbing activities. Section 3 outlines the management strategies recommended by the Mud Creek Watershed Restoration Council to address these problems. These recommendations are grouped into four categories and the specific recommendations are presented in Table ES.1: •

Stormwater: Strategies to address the volume, velocity, and quality of post-construction runoff from existing and future roads and commercial and residential development.

•

Nonpoint Source Pollution from Agricultural Activities: Strategies to reduce pesticides, nutrients, sediment and bacteria and other agriculture related non-point source pollution.

•

Habitat Degradation: Strategies to improve aquatic habitat needed by aquatic organisms to survive and reproduce in a stream. The recommendations address the causes of habitat degradation including sedimentation, bank erosion, channelization, lack of riparian vegetation, loss of riffles or pools, loss of woody habitat and streambed scour (i.e., flow that washes away habitat).

•

Upland Sources of Sedimentation: Strategies to reduce sediment pollution from construction activities and unpaved roads and driveways.

Section 4 outlines the next steps for the Mud Creek Watershed Restoration Council. These steps include: •

Present the Mud Creek Watershed Restoration Plan to the community.

•

Restructure the Mud Creek Watershed Restoration Council as a formal committee and seek appointments from the appropriate stakeholder groups.

•

Hire a Watershed Coordinator to work with stakeholders and agency partners to implement the watershed plan.

•

Evaluate the management strategies and set long-term and short-term implementation priorities.

•

Set measurable goals to track progress and document accomplishments.

•

Secure grants, as needed to implement education and restoration strategies.

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Table ES.1: Proposed management strategies for addressing water quality and habitat concerns in the Mud Creek watershed. Lead Agency or Organization1

Management Strategies

Funding2

STORMWATER •

Develop and/or refine existing stormwater management ordinances and floodplain development ordinances.

Local Governments

No cost

•

Provide incentives to local residents to reduce stormwater runoff from existing and new development.

Local Governments

Tax credits

•

Review existing development ordinances and building codes for opportunities to minimize impervious surfaces.

Local Governments

No cost

•

Educate businesses and citizens about stormwater management issues and actions they can take to reduce these impacts.

Local Governments, Council, CE

Grants

•

Consider establishing a stormwater utility to fund the stormwater program including improvements to the existing stormwater collection system.

Local Governments

Grants

•

Map existing stormwater collection systems to identify illicit connections and develop a strategy for redirecting these discharges to proper wastewater treatment facilities.

Local Governments

Local $$, Grants

•

Implement a Stormwater BMP Retrofit Program to identify opportunities to reduce stormwater impacts from existing development.

Local Governments, Council CE

Grants

•

Promote pollution prevention and stormwater management by implementing BMPs on government owned facilities including motor fleet maintenance areas, parks, and other suitable sites.

Local Governments, Council

Grants

•

Encourage local businesses to implement stormwater BMP retrofits by creating an award program to cite local businesses’ accomplishments

Local Government, PEP

Private sector

AG NON-POINT SOURCE POLLUTION •

Promote innovative pest management practices to reduce the amount of pesticides applied in the watershed and to reduce the likelihood for pesticides to enter streams.

S&WCD, CE

ACSP

•

Find research on pesticide drift management and work to develop new Ag Cost Share Practices to minimize pesticide drift.

S&WCD, CE

Unknown

•

Work with willing landowners to stabilize streams near orchards and row crops to minimize the transport of historic pesticides.

S&WCD

ACSP

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Lead Agency or Organization1

Management Strategies

Funding2

AG NON-POINT SOURCE POLLUTION continued…. •

Work with willing landowners to implement buffers and conventional conservation practices such as cover crops, no till, field borders, filter strips, on row crop land.

S&WCD

ACSP

•

Initiate groundwater monitoring to determine if historic pesticides are moving from the soils of ag fields to streams through the groundwater.

DWQ

Unknown

•

Work with willing landowners to implement animal waste practices such as livestock exclusion, feed/waste structures, stream crossing and buffer strips to protect water quality.

S&WCD

EQIP, ACSP

HABITAT DEGRADATION •

Restore 15,000 feet of the most critically eroding streams in the Mud Creek watershed to improve habitat and water quality.

NCWRP

NCWRP

•

Restore native vegetation along streams to stabilize streambanks and improve habitat.

Local Governments

Grants

•

Educate landowners about the importance of riparian buffers for streambank stabilization, water quality and habitat.

Council, CE

Grants

•

Evaluate the benefits of a buffer ordinance to protect lands adjacent to streams from future development activities.

Local Governments

Unknown

•

Permanently protect high priority wetlands and riparian buffers.

Local Governments, CMLC, ACGC

Grants

UPLAND SOURCES OF SEDIMENTATION •

Consider the benefits of a local Sediment and Erosion Control Program to oversee local development activities.

Local governments

Permit Fees

•

Educate excavators and the public about how to control erosion.

Local govts., CE

Grants

•

Reduce the sediment pollution from unpaved roads, eroding road banks, and roadside ditches.

Local governments, DOT, HOA

DOT

1

Lead Agencies or Organizations are defined as follows: Council-Mud Creek Watershed Restoration Council; Local Governments – Henderson County, Hendersonville, Flat Rock, and Laurel Park; PEP-Partners for Economic Progress; S&WCD-Henderson Soil and Water Conservation District; CE-Henderson County Cooperative Extension; DWQ-Division of Water Quality; NCWRP-North Carolina Wetlands Restoration Program; CMLC-Carolina Mountain Land Conservancy; ACGC-Apple Country Greenways Commission; DOT-North Carolina Department of Transportation; HOA-Home Owners Associations.

2

ACSP-Agriculture Cost Share Program; EQIP-Environmental Quality Incentives Program; Grants – could include EPA 319 Nonpoint Source grants, NC Clean Water Management Trust Fund Grants; NCWRP-Wetland and Stream Restoration Funds; DOT-Regional road maintenance funds.

Executive Summary

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SECTION 1: PROJECT OVERVIEW

1.1

Introduction Figure 1.1: Map of the Mud Creek Watershed.

Henderson County is growing at a rapid rate and much of this growth is occurring in the Mud Creek watershed (Figure 1.1). Across the watershed, developers are converting apple orchards and pasture lands and clearing forested hillsides for residential and commercial developments. Water quality problems associated with growth and development, as well as agricultural practices, are evident in many streams in the Flat Rock Mud Creek watershed. Mud Creek and two of its tributaries, Clear Creek and Bat Fork, are currently on the state’s 303(d) List of Impaired Waterbodies. The Volunteer Water Information Network (VWIN) operated by the University of North Carolina at Asheville rates many streams in the Mud Creek watershed as below average and poor. In addition to current landscape changes and uses, historic practices such as draining and filling wetlands, channelizing streams and clearing streamside vegetation further compromise the integrity of these natural systems and exacerbate the effects of growth and development on stream health and increase the intensity and frequency of flooding. In late 1998, the Division of Water Quality (DWQ) awarded Land of Sky Regional Council of Governments (LOSRC) a grant to work with local stakeholders to develop a plan for addressing water quality problems in the Mud Creek watershed. In 1999, DWQ received a grant from the NC Clean Water Management Trust Fund (CWMTF) to identify causes and sources of stream impairment through intensive monitoring and analysis and to develop watershed management strategies for eleven impaired watersheds across the state. The Mud Creek watershed was selected as one of the eleven watersheds in the Watershed Assessment and Restoration Project (WARP). Concurrently, the NC Wetlands Restoration Program (NCWRP) was interested in developing a local watershed plan for the Mud Creek watershed in order to identify potential restoration projects that the NC Department of Transportation (DOT) can implement to fulfill future compensatory mitigation requirements. NCWRP agreed to collect additional stream and watershed data to supplement WARP and LOSRC efforts already underway in the watershed through a partnership with the Tennessee Valley Authority (TVA). Section 1: Project Overview

Page 1

For the past two years, local stakeholders and state and federal resource managers have gathered data collaboratively and established priorities for restoring the Mud Creek watershed. This document represents the culmination of efforts undertaken by these partners to evaluate all possible sources and causes of water quality degradation and recommend a comprehensive set of strategies for addressing these problems.

1.2

The Mud Creek Watershed Restoration Council

In the Spring of 2000, the LOSRC established the Mud Creek Watershed Restoration Council (Council) to provide a forum for local stakeholder participation in the development of the Watershed Restoration Plan for Mud Creek. Council members include local government officials representing Henderson County and the three municipalities in the watershed (Hendersonville, Laurel Park and Flat Rock), state and federal agency officials, and business, environmental and community group representatives. A list of organizations participating on the Council as of December 2002 is presented in Appendix A. The Council holds monthly or bimonthly meetings that are open to the public. The Council’s mission statement and goals are: Mission: The Mud Creek Watershed Restoration Council is a diverse group that strives to improve and protect water quality throughout the Mud Creek watershed. Goals: • Develop a restoration plan and implementation strategy to improve water quality in the Mud Creek watershed based on the Division of Water Quality’s watershed assessment and Tennessee Valley Authority’s Integrated Pollutant Source Identification data. • Increase public awareness about water quality problems in the watershed including sedimentation and stormwater. • Enhance public appreciation for the Mud Creek watershed through education and outreach. • Promote the conservation of farmland and open space in the watershed to protect water quality. • Promote the reduction of flooding and its impacts in Hendersonville. • Promote the restoration of wetlands and educate people about their value. • Set water quality priorities and seek funding to implement a restoration plan. To streamline the planning process, the Council established three subcommittees charged with addressing a unique component of the planning effort: Technical (collect data and review existing data), Education (public outreach) and Implementation (identify issues, document existing programs, develop recommendations). The Subcommittees met independently and reported their progress at the “full” Council meetings. A complete list of subcommittee tasks and accomplishments is included as Appendix B.

1.3

NC Division of Water Quality Watershed Assessment and Restoration Project

In 2000, the NC Division of Water Quality (DWQ) initiated a comprehensive study of the Mud Creek watershed. This study is part of the Watershed Assessment and Restoration Program (WARP), a study of eleven watersheds across the state being conducted with funding from the NC Clean Water Management Trust Fund. Each of the watersheds in this study contains streams considered impaired because they are unable to support healthy aquatic communities. In the Mud Creek watershed, the study focused on three impaired streams: Mud Creek, Clear Creek and Section 1: Project Overview

Page 2

Bat Fork. The overall goal of the project was to provide the foundation for future water quality restoration activities by: 1) identifying the most likely causes of biological impairment (such as degraded habitat or specific pollutants); 2) identifying the major watershed activities and sources of pollution contributing to those causes (such as stormwater runoff from particular urban or rural areas, streambank erosion, or hydrologic modification); 3) outlining a watershed strategy that recommends restoration activities and best management practices (BMPs) to address these problems and improve the biological condition of the impaired streams. As part of this study, DWQ conducted extensive biological assessments in the Mud Creek watershed, sampled ambient and storm water quality and walked many miles of streams in the watershed to assess stream habitat, morphology, and riparian zone condition. The study also evaluated watershed hydrologic conditions, land use, land management activities, and potential pollution sources. WARP staff, located in Asheville, participated in Mud Creek Council meetings and worked closely with local resource management professionals to draw on the concerns and experience of watershed residents, local governments and others in evaluating the nature of water quality problems and outlining potential solutions. Once complete, the assessment report describing conclusions on these issues will be available to the CWMTF, watershed stakeholders, and other interested parties through the DWQ website. Preliminary data from this report are summarized in Section 2.

1.4

NC Wetlands Restoration Program Local Watershed Planning

In 2000, the NCWRP initiated a Local Watershed Planning program to conduct detailed restoration planning in a limited number of Targeted Local Watersheds across the state. These locally-based plans include a comprehensive watershed assessment to identify causes and sources of nonpoint source impairment. The NCWRP will use these plans to identify wetland and stream restoration projects to meet projected Department of Transportation compensatory mitigation requirements. Through this process, the NCWRP will work with local stakeholders to identify and prioritize wetlands areas, stream reaches, riparian buffer areas and best management practices that will provide significant water quality improvement and other environmental benefits to local watersheds. The NCWRP coordinates with local community groups, local governments, and others to develop and implement these plans. The NCWRP initiated the local watershed planning process in the Mud Creek watershed to complement the efforts underway by the DWQ and Mud Creek Watershed Restoration Council.

1.5

Tennessee Valley Authority Integrated Pollutant Source Identification

In 2000, the Tennessee Valley Authority developed a set of Integrated Pollutant Source Identification (IPSI) tools to help DWQ, the NCWRP and the Mud Creek Watershed Council identify and prioritize water quality improvement and protection measures in the Mud Creek watershed. The IPSI consists of a geographical database of watershed features such as land cover, estimates of impervious land cover, streams, soils, slope, and information about potential nonpoint sources of pollution including streambank erosion sites, livestock operations, and unpaved roads. The TVA IPSI data and methods are summarized in the report Mud Creek Watershed Nonpoint Source Pollution Inventory and Pollutant Load Estimates (TVA, 2001). A subset of the TVA IPSI data are summarized in Section 2. The complete report summarizing the IPSI data for the Mud Creek watershed is available at http://h2o.enr.state.nc.us/wrp/pdf/lwp/mud_creek_lwp_ipsi.pdf. Section 1: Project Overview

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SECTION 2: MUD CREEK WATERSHED CHARACTERIZATION

2.1

Introduction

This section summarizes current watershed conditions in the Mud Creek watershed including land use, water quality, channel and buffer conditions, habitat and wetlands. The objective of this analysis is to characterize existing watershed conditions and identify existing and potential sources of water quality degradation. The Tennessee Valley Authority’s (TVA) Integrated Pollutant Source Identification (IPSI) for the Mud Creek watershed served as an important source of data on land use/cover, imperviousness, and stream channel and riparian conditions. The IPSI is a geographic database and pollutant loading model based on interpretation of lowaltitude color infrared aerial photographs taken in March 2001 (TVA, 2001). In addition, the Council also relied heavily on water quality and habitat assessment data gathered by WARP and water quality monitoring data collected by VWIN.

2.2

Hydrology and Sub-Watershed Delineation

The Mud Creek watershed is 113 mi2, comprising approximately one-third of Henderson County’s land area. Mud Creek begins in southwest Henderson County and flows east and north through Hendersonville to the French Broad River (Figure 2.1). The watershed is bounded to the east and south by the Tennessee Valley Divide, to the north by a steep mountain range and to the west by a lower divide. Hendersonville receives an average of 56 inches of rainfall annually. Western North Carolina has been in a drought since mid1998, and rainfall at Hendersonville has been 84%, 75%, and 76% of the annual average for years 1999, 2000, and 2001, respectively.

Figure 2.1: Streams in the Mud Creek Watershed.

Section 2: Watershed Characterization

Page 4

The size of the watershed and variability of stream types make it difficult to generalize watershed conditions. To deal with these issues, the watershed was divided into five subwatersheds based upon topography, hydrology and land-use considerations. The subwatershed boundaries are shown on Figure 2.2. Table 2.1: Summary of area, stream miles and slope by subwatershed. Subwatershed Name

Drainage area

Stream Miles

Average Slope

Clear Creek

44.5 sq. miles

136

16%

Bat Fork

8.6 sq. miles

57

6%

Devils Fork

16.4 sq. miles

34

5%

Upper Mud Creek

20.5 sq. miles

61

17%

Lower Mud Creek

22.8 sq. miles

80

11%

112.8 sq. miles

368

14%

Total

Figure 2.2: Subwatersheds in the Mud Creek Watershed.

Section 2: Watershed Characterization

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2.3

Soils

Three general soil associations comprise the majority of the Mud Creek watershed soil types— (1) the Codurus-Toxaway-Rosman association, which are floodplain soils and consist of well drained to very poorly drained soils that have loamy and sandy subsoils, (2) the HayesvilleBradson association, which are soils on ridges and stream terraces and consist of gently sloping to moderately steep, well drained soils that have loamy and clayey subsoil, and (3) the EvardEdneyville-Ashe association, which are soils occurring on mountain ridge tops and side slopes and consist of sloping to very steep, well drained and somewhat excessively drained soils that have loamy subsoils (USDA, 1980). Hydric soils figure prominently in floodplain areas, especially in the Bat Fork, upper Mud Creek, the southern part of lower Mud Creek, and Devils Fork subwatersheds. Four percent of soils (4.1 mi2) in the watershed are hydric, and another seven percent (8.3 mi2) have hydric inclusions. Many of these soils are actively drained for agriculture, and a small proportion has wetland vegetation.

2.4

Land Use/Land Cover in the Mud Creek Watershed

Land use patterns can have a profound effect on water quality and stream hydrology. To assess land use patterns in the Mud Creek watershed we evaluated land use and land cover data generated by TVA from aerial photographs taken in March 2001. TVA’s Integrated Pollutant Source Identification (IPSI) determined that 45 percent of the Mud Creek watershed is forested, 25 percent is residential, commercial or industrial, and 23 percent is agricultural. Although the predominant land cover in the Mud Creek watershed is still forest cover, the watershed is experiencing rapid growth and development due to increasing popularity as a retirement community. On the whole, agriculture is declining in Henderson County. There was a loss of 25% of farmland between 1987 and 1997, and much of this land is being converted to residential land. Agricultural commodities are changing, as well, with sod farms, and plasticulture vegetables replacing the traditional vegetable farms, orchards, corn, and dairies. Most of the forested land is along the northern and southern ridges that border the watershed, and, accordingly, the Clear Creek and upper and lower Mud Creek subwatersheds have 39-60 percent of their land use in forest. However, these areas are desirable for homesites, and new development is occurring in these steeper areas. The southern ridge of the Bat Fork subwatershed, for example, is a patchwork of homesites surrounding the Kenmure golf course. Agriculture is a significant portion of the watershed, accounting for more than a fifth of each subwatershed except those of upper and lower Mud Creek. Apple orchards are prominent in the valleys and on gentle slopes of the Clear Creek and Devils Fork subwatersheds and the Dunn Creek area of the Bat Fork subwatershed. Pasture, often for beef cattle, is sited along stream valleys and accounts for at least nine percent of land use/cover in all subwatersheds. It is particularly notable along the mainstems of Clear and Mud Creeks, but also occurs along many tributaries. Row crops are usually in flat floodplain areas, and corn and market vegetables (e.g., squash, beans, tomatoes, and peppers) are common.

Section 2: Watershed Characterization

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Table 2.2. Percentage of subwatershed area by land use/cover. Bat Fork (8.6)

Clear Creek (44.5)

Forest

31

50

20

60

39

45

Wetland

1

0

1

0

3

1

Transitional area

5

4

5

1

3

4

Open maintained

3

0

2

2

2

2

Orchard

4

12

13

0

0

7

Row crop

4

3

9

2

2

3

Pasture

15

15

22

11

9

13

Residential

24

12

24

21

31

20

Commercial/Industrial

10

2

4

1

9

5

Disturbed

1

0

0

0

1

1

Other

1

1

1

1

1

1

Watershed Name (Area sq. miles)

Devils Upper Mud Lower Mud Mud Creek Fork Creek Creek Watershed (16.4) (20.5) (22.8) (113)

*"Transitional area" is shrub/old field vegetation or unmanaged orchard. "Open maintained" is golf course, athletic field, cemetery, transmission or highway right-of-way, or airport grassed runway. "Disturbed" is clear cut forest, mining, construction, or other disturbed area. “Other” is water, dumpsites, or Christmas tree plantations.

Residential land accounts for almost a fourth of land in all subwatersheds except that of Clear Creek. Residential land spreads from Hendersonville west to Laurel Park and south to Flat Rock. North of Little Mud Creek, there is a broad swath of residential land along the Mud Creek corridor. Although residential land is not as predominant in the Clear Creek subwatershed, a shift from agricultural to residential land is apparent. Over one and one-half square miles of old apple orchard is no longer in production and in transition to other uses (particularly residential). This land area is more than 20 percent of the total area that is currently in apple production. Commercial and industrial land is concentrated in and around Hendersonville, following the US 64, I-26, US 25, and US 176 road corridors. Most of this development exists in valley areas along Mud Creek, lower Devils Fork, and Bat Fork.

Section 2: Watershed Characterization

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Figure 2.3: Generalized Land Use/Land Cover patterns in the Mud Creek watershed.

Section 2: Watershed Characterization

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2.5

Water Quality and Stream Health

The primary goal of the Mud Creek Watershed Restoration Council is to improve and protect water quality throughout the Mud Creek watershed. To accomplish this goal, the Mud Creek Council must understand the current condition of water quality and overall stream health in the watershed, how these conditions have changed over time and what might be causing these changes. The following section describes existing water quality and habitat data for the Mud Creek watershed and provides some general conclusions about these data. The data used for this characterization include DWQ basinwide monitoring data, WARP Mud Creek data and VWIN monitoring data. The purpose of this summary is to characterize water quality problems and stream health issues in the Mud Creek watershed based on these technical information sources and is not intended to provide detailed analysis of this information or to discuss sampling and data methodologies.

2.5.1 General Conclusions of WARP Assessment WARP used the data summarized in the following sections to determine causes and sources of biological impairment for Bat Fork, Clear Creek, Devils Fork and Mud Creek. The recommendations listed in Section 3 of this document are designed in large part to address the problems that the WARP study has illuminated. WARP concluded that a number of factors impact water quality and stream health in the Mud Creek watershed: •

Pesticides: Based on the data available, pesticides are likely the primary factor causing toxic impacts to benthic macroinvertebrate communities in apple growing areas (including Clear Creek and Devils Fork). Both current use pesticides used on apples and row crops and past use pesticides used on both agricultural and residential land may play a role in stream degradation. Toxic impacts were also noted in upper Mud Creek and tomato/pepper pesticides were pinpointed as a most likely source of toxicity.

•

Habitat Degradation: Poor in-stream habitat for biological communities was a widespread problem in the watershed, but most notable in Mud Creek and Bat Fork. Lack of woody riparian vegetation, extensive channelization, and sedimentation (from both in-stream and upland sources) are key factors responsible for habitat degradation.

•

Stormwater: In urban streams, the combined factors of toxicants (e.g., metals, organic pollutants, and pesticides) and scouring energy from high stormflow volumes severely limit biological communities.

•

Nonpoint Source Pollution: Nutrient enrichment was a notable problem in Clear Creek and Devils Fork. Nutrient sources include cattle with stream access and possibly straight pipes and failing septic systems.

•

Cumulative Impacts: Combined impacts of toxicants from agriculture and urban sources, scour from high stormflow volumes, poor in-stream habitat, and a lack of tributaries with healthy biological communities are responsible for chronically impaired biological communities in lower Mud Creek.

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WARP focused on 303(d) listed streams (Bat Fork, Clear Creek, and Mud Creek). They did not intensively study many smaller streams in the watershed. However, the issues identified above are likely important for many streams in the Mud Creek watershed.

2.5.2 DWQ Use Support Ratings In 1997, DWQ assessed streams in the Mud Creek watershed as part of the basinwide planning process for the French Broad River Basin and determined that Mud Creek, Bat Fork and Clear Creek do not support their use classifications for Class C waters. The use classifications for streams in the Mud Creek watershed are shown in Figure 2.4. Class C waters are protected for secondary recreation, fishing, and aquatic life. Class C is the minimum protection class for freshwaters. Class B waters are protected for primary recreation including frequent, organized swimming. Water quality standards applicable to Class C apply to Class B waters in addition to more stringent standards for bacterial pollution. “Tr” is a supplemental classification designed to protect freshwaters for natural trout propagation and the survival of stocked trout, it does not denote the presence of trout in a stream. Trout water (Tr) sections of Class B and C waters retain all respective water quality standards with the addition of more stringent standards for dissolved oxygen, temperature, turbidity and chlorine. Figure 2.4: Use Classifications for streams in the Mud Creek Watershed

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To determine the biological health of streams, DWQ evaluates the composition and diversity of stream benthic macroinvertebrate communities every five years. These communities can provide important information about water quality stressors such as excessive nutrients, toxicants, and sediment pollution. In addition, macroinvertebrates and fish communities respond to the quality of in-stream habitat, which is influenced by factors such as sedimentation. Thus, biological communities are reflections of stream integrity as a whole. Figure 2.5 shows the use-support rating assigned by DWQ for streams in the Mud Creek watershed and the location of the five biological monitoring sites that DWQ sampled in 1997. Streams rated as either Not Supporting or Partially Supporting are considered impaired by the DWQ. Mud Creek, Bat Fork and Clear Creek are listed on the state’s 303(d) List of Impaired Waterbodies as Biologically Impaired Waters with no identified cause of impairment. One goal of the DWQ Watershed Assessment and Restoration Project (WARP) is to determine the cause of impairment of these streams. A summary of the data collected as part of the WARP study is presented in Section 2.5.3. A complete summary of the DWQ Use Support Ratings and Stream Use Classifications for the French Broad River Basin, including the Mud Creek watershed is available at http://h2o.enr.state.nc.us/basinwide/french/frenchbroad_wq_management_plan.htm. Figure 2.5: Use-support Ratings for streams in the Mud Creek Watershed.

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2.5.3 DWQ’s Watershed Assessment and Restoration Project (WARP) In 2000, WARP launched a comprehensive assessment of the Mud Creek watershed to: 1) determine the most likely causes of biological impairment; 2) identify the major watershed activities and pollution sources; and 3) outline a general watershed strategy that recommends restoration activities and best management practices (BMPs) to address the identified problems. As part of this assessment, WARP conducted a wide range of data collection activities, including benthic macroinvertebrate and water quality sampling, which are summarized in this section. A detailed description of all their data collection methods as well as an analysis of their findings is presented in the report titled Biological Impairment in the Mud Creek Watershed (DWQ, 2003). Biological Sampling: WARP conducted biological sampling at 23 sites in the Mud Creek watershed and two reference sites outside the watershed between July 2000 and October 2001 (Figure 2.6). WARP used benthic macroinvertebrate communities to characterize steam health. WARP evaluated a number of community characteristics, including diversity, pollution tolerance of the community as a whole, and species composition, to determine community health and the types of pollution impacting the streams. In addition to gathering data at known problem sites in the watershed, WARP also collected samples at reference sites to establish benchmarks for healthy biological communities and conducted habitat assessments at all sites to determine if the lack of habitat might also be a potential source of stress for these communities. Habitat scores considered channel modifications, in-stream habitat (such as leafpacks, sticks, large woody debris and rocks), sedimentation, riparian zone integrity, and riffle and pool frequency. WARP found that the healthiest communities are in headwater streams with adequate habitat that drain forested areas of the watershed—Laurel Fork, upper Cox Creek and Harper Creek in the Clear Creek subwatershed and upper Mud Creek above Walnut Cove Road. Degraded benthic communities were found at almost all other sample sites.

Figure 2.6: WARP Biological Monitoring Sites

Degraded biological communities were reported from the urban portions of the watershed, including Devils Fork at US 64 and Mud Creek at 7th Avenue (in Hendersonville). Habitat scores were very low in these urban areas and likely contributed to community

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degradation. In addition, the WARP study suggested that the high velocity and volume of stormwater runoff generated by urban development scour stream channels, removing key habitat such as leafpacks and woody debris. Many of the biological sampling sites showed biological communities exposed to periodic toxic stress, most notably the sites downstream from large areas of apple orchards and row crops. Suspecting that pesticides might be impacting communities in lower Clear Creek and Devils Fork, WARP sampled these sites before, during and after the growing season. Figure 2.7 illustrates the benthic community status at the biological sampling sites in the Clear Creek and Devils Fork subwatersheds and their proximity to orchards and row crops. A number of impacts other than toxicity likely influence the benthic communities at some sites. Benthic community analysis for Clear Creek at Mills Gap Road and both sites on Devils Fork showed signs of organic enrichment or high nutrients. WARP also determined that in upper Mud Creek and in many areas throughout the watershed, excess sedimentation exacerbates many of the primary causes of impairment. Figure 2.7: Apple orchards, row crops, and benthic macroinvertebrate communities in the Clear Creek and Devils Fork Subwatersheds.

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Chemical Water Quality Sampling: In addition to biological sampling, WARP also conducted extensive chemical water quality sampling to characterize water quality conditions in the watershed and to evaluate whether chemical and physical conditions might be negatively affecting benthic communities. WARP established five sampling stations at the downstream ends of the subwatersheds and evaluated these sites monthly for a standard set of parameters including pH, dissolved oxygen, temperature, metals, turbidity, and nutrients. Samples were collected during both baseflow and stormflow periods. WARP also collected grab samples at a number of sites in the watershed with known biological impairment. The purpose of the grab samples was to assess potential chemical stressors such as pesticides, hydrocarbons and volatile organic pollutants. Figure 2. 9 illustrates the location of WARP water quality sampling sites across the Mud Creek watershed. WARP chemical water quality monitoring data indicated that many streams in the Mud Creek watershed including upper and lower Mud Creek, Clear Creek, Devils Fork, and Bat Fork have higher nutrient and specific conductance levels than expected for unpolluted streams in the mountains. However, these levels were not high enough to affect biological communities or exceed NC’s standard or action levels. Dissolved oxygen levels in these streams were adequate for aquatic life. In upper Mud Creek and Bat Fork, fecal coliform bacteria levels were above the NC standards of 200 colonies/100mL. Although fecal coliform does not affect biological communities, it can indicate the presence of viruses and pathogens that pose a risk to human health.

Figure 2.8: Location of WARP water chemistry sampling sites.

Water samples taken during storms in the Clear Creek watershed had levels of insecticides that are above ecological screening benchmarks and may cause sub-lethal impacts to aquatic insects. Bed sediment samples collected from upper Mud Creek and Clear Creek provided evidence of both current and past use pesticide inputs. WARP identified pesticides as a cause of biological impairment in these streams.

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WARP also evaluated selected metals concentrations in the watershed including cadmium, copper, lead, silver and zinc. Median metal values for baseflow samples collected by WARP were generally below NC’s standards or benchmark levels. However, some stormflow samples exceeded the benchmark levels for cadmium, copper, lead and/or zinc. Bioassay results from these samples indicated that these metal levels were not acutely toxic; however, results from a Devils Fork sample taken below a large commercial area showed acute toxicity, likely due to high copper, lead, and zinc concentrations. For a more detailed discussion of the WARP monitoring protocol, sampling results and analysis, see the report titled Biological Impairment in the Mud Creek Watershed, 2003.

2.5.4 Volunteer Water Information Network The Volunteer Water Information Network (VWIN) monitors 33 sites in Henderson County monthly for a wide range of water quality parameters including sediment, water clarity, pH, alkalinity, conductivity, heavy metals, and nutrients. Nine of these sites are located in the Mud Creek watershed (Figure 2.9). VWIN has monitored five of these sites monthly for nine years and the other three for over three years. This information is valuable in assessing current water quality conditions and trends in the Mud Creek watershed. As shown in Figure 2.9, none of the sites monitored by VWIN in the Mud Creek watershed rate excellent, but three rate good. The remaining sites are either average (3), below average (2) or poor (1). To determine these ratings, VWIN compares nutrient, metals, and sediment values at these sites to a regional average for Western North Carolina. The regional average is a composite score developed from VWIN monitoring efforts in Henderson County as well as other western counties.

Figure 2.9: Water Quality rating for VWIN monitoring sites in the Mud Creek Watershed.

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Good Sites: Consistent with the WARP study, the most upstream sites show fewer water quality problems than sites located in the more developed areas of the watershed. However, even at the good sites, VWIN noted that nutrient concentrations at the Berea Church Road site have been unusually high at times and that turbidity, conductivity, lead, and all three nutrient levels at Clear Creek at Apple Valley Road are increasing over time. VWIN concludes that the increasing turbidity levels are probably the result of escalating land disturbing activities. Average Sites: VWIN rates three sites in the Mud Creek watershed, Brittain Creek, Bat Fork Creek, and Mud Creek at 7th Avenue as average. VWIN data indicate that conductivity levels and heavy metals concentrations in Brittain Creek have been high at times and construction sites may be the greatest contributor of sediment to the creek during rains. The site on Mud Creek at 7th Avenue shows high concentrations of zinc probably due to road runoff and elevated nutrient concentrations that may be coming from upstream sources. Diverting wastewater effluent from the GE plant to the Hendersonville wastewater treatment plant has helped to improve water quality in Bat Fork, however nutrients and conductivity levels continue to be abnormally high. VWIN suggests that livestock may be the main source of nutrients to Bat Fork. Below Average Sites: VWIN rates Devil's Fork and Clear Creek at Nix Road (the downstream site on Clear Creek) below average. The nutrient and conductivity levels measured at Devil's Fork suggest that agriculture may be the most important source of pollutants to this stream. Both of these streams have a heavy build-up of sediment in the downstream areas indicating that erosion and runoff, including sediment pollution from land disturbing activities, have probably been impacting these streams for a long time. Poor Sites: Mud Creek at North Rugby Road is one of three sites in Henderson County that rates poor. This site has consistently rated poor throughout the nine years of analysis. Nutrient concentrations are much higher than average and water clarity is consistently poor. Nutrient concentrations increase when stream flow decreases indicating a point-source for these pollutants. Clear Creek shows serious problems with sedimentation and VWIN indicates that land disturbing activities are probably a significant factor.

2.5.5 Channel and Riparian Buffer Condition Channel and buffer condition are important indicators of stream habitat and watershed health. Severely eroded streams produce significant quantities of sediment that are carried and deposited downstream where they smother aquatic habitat. In some cases, channels become so deep and wide that the stream can no longer access the flood plain during a significant storm event increasing the likelihood of flooding downstream areas. WARP walked many miles of stream in the Mud Creek watershed to document channel and riparian buffer condition, however this is a very time intensive effort and they were not able to observe every stream in the watershed. As part of the IPSI, TVA also evaluated channel and buffer conditions using aerial photography. These data are useful for documenting areas of the watershed with eroding streambanks and inadequate riparian buffers as well as streams channels that have been altered from their natural state.

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Channelized Streams: Channelization, or the straightening of streams, was a common practice in the Mud Creek watershed to improve drainage and increase valuable floodplain areas for farming. This practice destroys stream habitat by eliminating riffles and pools and meander bends. The practice also dramatically affects the watershed hydrology by deepening channels, lowering the water table and increasing the stress on streambanks during storm events. Over time, channelized streams can become very deep and overly wide with almost vertical streambanks that can collapse sending large quantities of sediment directly into the stream. If the streams become very incised, they will no longer over top their banks during storm events increasing the volume and velocity of stormwater to downstream areas. Historical topographic and parcel maps reveal that large-scale channelization of Mud Creek occurred between 1840 and 1890 (Figure 2.10). Many tributaries to Mud Creek, including Bat Fork and Devils Fork, were also channelized. Major floods of 1916, 1940, and 1964 caused much concern, leading to a number of stream channelization and dredging projects aimed at minimizing flooding problems.

Figure 2.10: Map of Hendersonville showing Mud Creek prior to channelization.

Table 2.3 illustrates the percentage of stream miles by subwatershed delineated as channelized by the TVA IPSI. Over 50% of the natural channels and aquatic habitat of Bat Fork and Devils Fork have been significantly altered by this practice. Biological monitoring data collected by WARP in these areas suggests that loss of habitat in these areas could be impacting the benthic communities in these subwatersheds. Eroding Streambanks: Although severe streambank erosion may be limited to short stream reaches, the sediment pollution from these eroding banks can have impacts throughout the watershed. The sources of excess sedimentation noted in stream channels throughout the Mud Creek watershed are often not readily apparent because the sediment is from eroding streambanks, and it is then transported and deposited downstream. Table 2.3 illustrates the percentage of streambank miles that are eroding in each subwatershed as determined by the TVA IPSI from aerial photography. Field assessments conducted by WARP staff suggest that these estimates are conservative probably due to the limitations of determining eroding banks from aerial photos. Although the TVA IPSI data indicate that only 18% of the streams in the Clear Creek subwatershed are eroding, a more detailed analysis of these data show that the impact of

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eroding streambanks is more significant in some areas of the watershed. In the Lewis Creek and Henderson Creek drainages, 37% and 25% of the streams are severely eroding. There are many potential factors that exacerbate streambank erosion including channelization, a lack of riparian vegetation to stabilize banks and cattle with direct access to streams. Locating eroding streams banks is a first step to addressing this problem; understanding the factors that contribute to the problem requires a more detailed analysis. Table 2.3: Channelization and Buffers in the Mud Creek watershed Percentage of Subwatershed Stream Miles Subwatershed

Channelized streams

Eroding Streambanks*

Adequate Buffers on Both Banks*

Bat Fork

56%

6%

15%

Clear Creek

28%

18%

11%

Devils Fork

55%

18%

2%

Upper Mud Creek

18%

12%

12%

Lower Mud Creek

28%

13%

9%

Total Watershed

33%

14%

11%

*Determined for a subset of streams (44% of total) that have a larger drainage area; adequate buffers are those with >= 30 ft of woody vegetation with >= 66% crown cover.

Riparian Buffer Condition: As shown in Table 2.4, very few of the larger streams in the Mud Creek watershed have adequate riparian buffers. Riparian buffers have many important watershed functions. The deep roots of riparian vegetation help to stabilize streambanks and reduce erosion. Overhanging tree limbs shade streams and keep waters cool in the summer to protect fish and other aquatic life. Adequately sized riparian buffers can also filter pollutants such as nutrients and sediment pollution that runs off adjacent fields and parking lots. Riparian buffers also provide a protected corridor for wildlife migration. For all these reasons, riparian buffer condition is an important indicator of stream health. TVA IPSI data provide information about the width and vegetation type and condition of riparian buffers for all streams deemed perennial. These “perennial” streams are a subset of streams (only 44% of the total stream miles identified by the IPSI) that have larger drainage areas and are an underestimate of true perennial stream miles. For this report, adequate buffers were determined as those with woody vegetation with at least 66% crown cover and a width of >30 ft. In general, adequate buffers are present along upper sections of the tributaries that drain the forested northern ridge. In the lower gradient areas that are primarily in agriculture, there are small stream sections that have adequate buffers in small forested patches. Based on this assessment, the current quality and distribution of adequate riparian buffers in the Mud Creek watershed is too limited to protect water quality and promote good aquatic habitat.

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2.6

Local Water Quality Initiatives

2.6.1 Local Environmental Ordinances A set of state and local regulatory programs impact development and water quality protection in the Mud Creek watershed, the most important of which are described below. Henderson County Ordinances •

Subdivision Ordinance and the Manufactured Home Park Ordinance: These ordinances require that stormwater drainage facilities be constructed to minimize erosion and sedimentation, minimize flooding, and avoid excessive discharge; however, specifications for post-development stormwater discharge volume and rate are not addressed. The Subdivision Ordinance requires that structures built upon lots within newly platted subdivisions must remain 30 feet from the edge of any blue line streams (as indicated on USGS 1:24,000 Topographic Maps). However, the ordinance does not require that the area within this setback remain vegetated or permeable to water.

•

Water Supply Watershed Protection Ordinance: This ordinance delineates the uses and development of land and structures in water supply watersheds within Henderson County in order to maintain the high quality of surface water; however, no streams in the Mud Creek watershed fall within this ordinance.

•

Farmland Preservation: This ordinance encourages the voluntary preservation and protection of farmland from non-farm development.

Hendersonville Ordinances •

Floodway and floodway fringe development. Development is limited in the floodway and floodway fringe in order to minimize public and private losses due to flood conditions. It provides guidance to control the alteration of natural floodplains, stream channels, and natural protective barriers involved in the accumulation of flood waters, including filling, grading, dredging, or other development which may increase erosion or flood damage. Redevelopment in the floodway and fringe is permissible provided there is no loss of flood storage and the project utilizes BMPs to reduce post-redevelopment stormwater rate if feasible.

•

Stormwater management. Any development that includes impervious surfaces greater or equal to 0.5 acres must submit a stormwater management plan with stormwater controls. Post-development runoff rate must not exceed the pre-development rate.

•

Natural Resources Protection Ordinance. This ordinance contains a stream buffer protection standard that requires protection of a 50 foot buffer on both sides of blue line streams identified on the current USGS quadrangle maps. Existing uses of the buffer zone are allowed. The 50 foot buffer is divided into two zones—a 30 foot area of undisturbed vegetation adjacent to the channel followed by a 20 foot belt of either managed or unmanaged vegetation.

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Flat Rock Ordinances •

Subdivision buffer requirement. This requires protection of a 50 foot set back on perennial streams, lakes, and wetlands as they appear on USGS topographic maps; the setback is divided into two areas—a 25 foot zone of natural vegetation adjacent to the channel followed by a 25 foot belt of either managed or natural vegetation. Perennial streams not on a USGS topo, require a 10 foot buffer of natural vegetation.

•

Floodplain ordinance. No structures, with some exceptions, or fill are allowed in the 100 year floodplain.

•

Stormwater management. Both subdivisions and other types of commercial and residential developments are required to construct stormwater drainage facilities to prevent downstream erosion/sedimentation and follow existing natural drainage. Where feasible, stormwater discharge points must discharge through vegetated areas. In addition, commercial and residential developments (excluding subdivisions) are required to have stormwater controls to insure that post-development stormwater runoff rates do not exceed pre-development rates.

2.6.2 Land Use Planning and Zoning Local governments use zoning and land use planning to guide growth, ensure adequate infrastructure and services and to protect environmental resources. Local zoning ordinances are a good indicator for how an area, like the Mud Creek watershed, might grow and develop and how this growth might impact water quality. Table 2.5 summarizes the current zoning in the Mud Creek watershed. The zoning categories used in Table 2.5 generalize some 63 distinct zoning classifications of the five governmental entities with zoning authority in the Mud Creek watershed. The “traditional” zoning districts, such as residential, commercial and industrial, account for more than 43% of the total Mud Creek watershed. Each of these zoning districts contains elements regulating lot size, structure size, and property line setbacks. To the extent that land use affects water quality, each of these districts can have considerable positive and negative implications for water quality. Most districts regulate the size of the lot, thus affecting density and potentially the degree of urban runoff. However, none of the districts regulate the amount of impervious surface or require permanent measures to control storm water runoff. Over 78% of the watershed falls within the zoning jurisdiction of Henderson County, with over 54% of the watershed falling within the County’s Open Use Zoning District. Through issuance of a special use permit, open use zoning allows for many land uses, such as mining and extraction operations and junkyards, that could pose a threat to water quality. Given the flexibility inherent in Open Use Zoning, it is difficult to project the potential impacts to water quality from future development in the watershed.

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Table 2.4: Summary of Zoning in the Mud Creek watershed. Generalized Zoning Category

Acres Per Category

Percentage of Watershed in Zoning Category

Commercial

3,295

5%

Industrial

1,138

2%

1,006

1%

Medium Density

10,929

15%

Low Density

15,045

21%

39,071

54%

43