Pitt County Government

Swift Creek

Pitt County and project partners received $167,300 in grant monies from the NC Clean Water Management Trust Fund (CWMTF) as part of a $214,300 watershed management initiative in the upper Swift Creek watershed. Project partners include the cities and towns of Greenville, Winterville, and Ayden, as well as the agencies Mid-East RC&D Council, the Pitt County Drainage Districts 3 & 7, and USDA-NRCS.

Click here for a map of the project area:
Project Area Map

Recent development in Greenville, Winterville, Ayden, and portions of Pitt County has impacted Swift Creek and its main tributary, Fork Swamp. Aging infrastructure, in addition to land use changes caused new development, has resulted in stormwater problems that contribute to the degradation of water quality and habitat in these streams. The project partners propose to address these problems now, when cost-effective solutions can be implemented to reduce the likelihood of future water quality degradation.

This proposed project has four goals: characterize long-term water quality through benthic macroinvertebrate community monitoring; target areas for riparian protection and stream enhancement; identify stormwater conveyance problem areas; and identify and prioritize stormwater best management practices (BMPs) within the project area.

Watershed Characteristics

Swift Creek has its headwaters in Pitt County and is the last major tributary to the Neuse River before it reaches its estuary near New Bern. Swift Creek and Fork Swamp flow south from the City of Greenville past the Towns of Winterville and Ayden into more rural areas near the Swift Creek confluence with the Neuse River. North of NC 102, 31% of the watershed is developed land use, while 69% of the area is characterized as agricultural or forest. Pitt County Planning Department estimates the watershed population in 2008 at 48,000. The population of Pitt County is projected to grow by 33% between 2000 and 2020, and the project area is experiencing the fastest growth.

Channelization of the upper Swift Creek stream network was completed in the 1970s and early 1980s using Federal PL 556 funds. Drainage modifications were undertaken to address long-term flooding problems that had impacted farmlands. Main channels were modified to carry rainfall from a two-year storm and the lateral channels were designed to carry rainfall from a five-year storm. The Swift Creek Drainage District was created to assist landowners and help maintain the channelized stream network.

In recent years water quality degradation has been reported in the upper Swift Creek watershed. The NC Division of Water Quality (NCDWQ), placed upper Swift Creek on the 1998 Clean Water Act Section 303(d) list of impaired waterbodies, based on impaired benthic macroinvertebrate communities (sample collected at NC 102 east of Ayden received a Poor rating in 1995). Agriculture and channelization were listed as potential sources of pollution in 2000; however, it is likely that urban runoff has the greatest current impact on the water quality and habitat of Swift Creek.

Channelization can contribute to water quality degradation. For this reason, it is not the preferred approach for floodway management. However, the work has been completed and maintenance agreements are in place. This project will not seek restore channelized streams, but to identify areas where a floodplain bench can be built within the existing channels to improve sediment transport and hold greater volumes of floodwater. Additional effort will be made in the uplands to detain storm runoff.

Comprehensive Watershed Plan - Need for the Project

Until recently, the County and local municipalities had few stormwater management measures in place. The County and the City of Greenville acted proactively when implementing the Tar-Pamlico stormwater requirements to include the Neuse watershed. Since 2004, the County had implemented the Pitt County Stormwater Ordinance (2004), a Stormwater Program Document (2004), developed stormwater reports, the Pitt County Riparian Buffer Protection Ordinance (effective 2007), the Greenway Plan (2006), and updated the Pitt County Zoning Ordinance (2006) to assist in stormwater control.

With the implementation of these new regulations, it is necessary to determine current stormwater control needs before future development takes place. The stormwater management measures in this proposal are targeted at managing current stormwater impacts and preventing future impacts. They will enhance and protect the less-impacted reaches and work towards removing Swift Creek from the 303(d) list. In addition, managing stormwater now will help to mitigate future flood impacts while giving the County a head start on responding to anticipated regulations, such as National Pollution Discharge Elimination System (NPDES) Phase II stormwater requirements.

The project will achieve its goals through a series of concurrent efforts. The stormwater conveyance system investigation will identify existing infrastructure problems and provide a basis to direct and prioritize management efforts and additional assessment. Monitoring of benthic macroinvertebrate communities will lead to a better understanding of the causes and sources of the impairment. The identification of potential stormwater BMP sites will provide the County and project partners with a framework for future stormwater management activities and strengthen grant proposals to help fund BMP construction. The outcomes of this project will include: subwatershed characterization; identification of existing infrastructure problems; development of criteria to assess current and future BMP needs; benthic macroinvertebrate monitoring; riparian protection and stream enhancement sites; a weighted list of BMP projects; educational workshops; and, a watershed management plan

This project is a collaborative effort to improve stormwater management in the upper Swift Creek watershed. The project team includes resource professionals and agency staff from eleven area organizations. In addition to Pitt County, project participants contributing matching funds in cash and/or in-kind services include the City of Greenville, the Town of Winterville, the Town of Ayden, Pitt County Drainage Districts 3 & 7, Mid-East RC&D Council, USDA-NRCS, and Pitt County Soil and Water District. Also, representatives from NCDOT, East Carolina University, and Pitt Community College are expected to attend project meetings and may contribute volunteer time or facility resources. Together, these participants form a strong, committed team to address water quality issues in the watershed.

Plan of Work

Pitt County officials will develop a watershed management plan for upper Swift Creek and Fork Swamp (a total area of approximately 45 square miles, see attached Figures). The primary goals of the watershed plan will be management of stormwater runoff from existing developed areas and floodplain management through strategic conservation easements and selective enhancement. The challenge is to improve water quality in an area with a channelized stream network. The project approach includes six tasks, described below: subwatershed characterization, benthic macroinvertebrate monitoring, riparian protection and stream enhancement, BMP site identification and prioritization, educational workshops, and a published watershed action and strategic plan.

Task 1. Subwatershed Characterization.

• Gather existing information on land use (GIS), stormwater conveyance (GIS and database for Winterville and Ayden), state and local regulations, projected future growth, water quality, and floodprone areas.
  
• It is assumed that no new stormwater conveyance mapping will be done. (What about areas that have not been mapped? Greenville)
  
• Divide project area into approximately 10 to 12 subwatersheds and characterize each based on existing information. Scrutinize the results to identify problem areas and areas worthy of protection.
  
• This task will help to establish the needs for each subwatershed in terms of this project and future management issues.

Task 2. Conduct benthic macroinvertebrate monitoring.

• Conduct benthic macroinvertebrate monitoring at selected subwatershed sites for the purpose of characterizing long-term water quality and instream habitat.
  
• Seek NC Division of Water Quality’s assistance and contract experienced biologists to sample the benthic macroinvertebrate communities and interpret the results. This work would include a habitat assessment following EPA’s Rapid Bioassessment Protocol. This benthic monitoring task would determine if the aquatic life designated use is impaired, and, if so, the potential causes of the impairment(s).

Task 3. Target riparian protection and stream enhancement.

• Building on information from Task 1, through a combination of GIS analysis and field visits, identify sites that provide water quality benefits and flood water storage and target them for conservation.
  
• GIS analysis will identify large parcels adjacent to streams with flood problems. Contact landowners of most promising parcels to obtain permission to field verify these sites.
  
• For stream enhancement, identify stream reaches that could be enhanced by creating floodplain benches and planting them with native riparian vegetation. Obtain landowner permission to survey 10 sites. The surveys will include measurement of at least two channel cross sections per reach.
  
• Baker Engineering will conduct analysis of bankfull dimensions to determine the appropriate elevation of a floodplain bench and if a suitable one is present. If one is not, an enhanced channel cross section will be recommended.
  
• Grade control to prevent channel incision will also be targeted where it would be beneficial. Adding stream pattern (e.g., meander bends) will not be targeted but if site constraints allow, its viability may be considered.
  
• The project will work with the Pitt County Drainage Districts on this task so that the enhancement and conservation measures do not conflict with the districts’ maintenance efforts.

Task 4. BMP site identification and prioritization

• Through a combination of GIS analysis and field visits, identify up to 30 sites as candidates for stormwater BMP sites and identify the type(s) of BMP appropriate for each location.
  
• Target areas within the three municipalities or those with urbanizing land.
  
• Innovative stormwater BMPs that use infiltration (e.g., bioretention areas) and natural filtering processes (e.g., constructed wetlands) will be preferred. The potential for constructing detention basins will be explored with the regulatory agencies.
  
• Estimate pollutant loads with and without a BMP at each potential site using basic modeling techniques (e.g., Schueler’s Simple Method).
  
• Evaluate each candidate BMP for probable effectiveness, initial and ongoing costs, and construction feasibility. Develop a potential BMP database to archive the results.
  
• Rank the candidate BMPs in terms of desirability for implementation.

Task 5. Educational workshops.

• Annual or bi-annual workshops will be held to educate local officials and the public about the project and stormwater management.
  
• This task will provide matching funds through in-kind services.
  
• Teach the public attendees how they can improve water quality and flooding. Examples include pollution prevention measures and homeowner stormwater management, including construction of bioretention areas and use of cisterns.
  
• Seek to build support for BMP and conservation/enhancement sites.
  
• Partner with East Carolina University and Pitt Community College on this task and possibly others.
  
• Baker Engineering will prepare and deliver a PowerPoint presentation on the comprehensive watershed plan (this project) at one of the workshops.

Task 6. Publish report – Upper Swift Creek and Fork Swamp Watershed Action and Strategic Plan.

• Baker Engineering will produce a plan document that will include GIS figures, results tables, and text.
  
• Detailed observations from existing data in Task 1. Will include analyses of designated subwatersheds.
  
• Summary of process and areas targeted for conservation in Task 3.
  
• Summary of process and areas targeted for enhancement in Task 3.
  
• Summary of BMP needs and opportunities identified in Task 4.
  
• Specific recommendations for improving the stormwater water conveyance systems
  
• Provide ten hard copies and a digital copy of the report.

Work on this plan is scheduled to begin in Spring 2009 with the anticipated completion date of Spring 2011.


Fork Swamp