BUILDING LOCAL OWNERSHIP INTO WATERSHED PLANNING IN THE TARHEEL STATE

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Abstract:

A Memorandum of Agreement between the N.C. Department of Environment and Natural Resources, N.C. Department of Transportation (NCDOT) and the U.S. Army Corps of Engineers initiated the N.C. Ecosystem Enhancement Program (EEP) in July 2003. The programmatic philosophy driving EEP is two-fold: a desire to have appropriate mitigation projects identified in advance of impacts permitted under Clean Water Act Section 401/404 provisions; and the recognition that comprehensive local watershed assessment and planning, based on a collaborative stakeholder process, will provide the best framework for selecting and implementing effective watershed improvement projects. Identified projects typically include “traditional” compensatory mitigation efforts (stream, wetlands and riparian buffer restoration or enhancement projects) as well as less conventional watershed projects such as urban and agricultural stormwater best management practices (BMPs), greenways establishment, preservation/protection areas and possibly other policy-based recommendations. Through the local watershed planning process, EEP seeks to improve the ecological effectiveness of restoration projects by identifying projects that will provide the most cost-effective benefits to watershed functional health prior to the occurrence of the construction impacts requiring mitigation.

In 2002, the predecessor agency to EEP selected the Morgan, Booker and Bolin Creek watersheds in the central North Carolina Piedmont ecoregion as high-priority areas for Local Watershed Planning due to three primary factors: 1) documented water quality and aquatic habitat problems in selected stream segments; 2) the opportunity to partner with local agencies and municipalities that have already initiated watershed protection or restoration efforts; and 3) ongoing threats to local watershed health attributable to agricultural activities, urban/suburban development, clearing of riparian buffers, and other nonpoint sources. This watershed assessment and planning effort is referred to henceforth as the Morgan Creek Local Watershed Plan (LWP). The study area is shown in Figure 1 in the context of the larger Haw River watershed within the upper Cape Fear River basin.

The Local Watershed Planning Area is in Orange, Chatham and Durham Counties, and encompasses the towns of Carrboro and Chapel Hill, and the campus of the University of North Carolina at Chapel Hill. Prior to initiating the planning effort, EEP staff obtained Memorandums of Agreement from each jurisdiction supporting it by agreeing to supply available data and information pertaining to the study area, and receive the recommendations indicated in the completed plan. They also agreed to designate a representative as a point of contact for the EEP and to participate on the Local Watershed Planning Team. Staff from pertinent state and federal resource agencies and members of local environmental advocacy groups, including Friends of Bolin Creek and the Morgan Creek Valley Alliance, were also recruited to participate on the Local Watershed Planning Team. The project coordinator for EEP, a stakeholder facilitator from the Cape Fear River Assembly, and the project manager from the private consulting firm hired to perform the technical assessment portions of the study lead the team through a two-year process to develop the final LWP. The process of developing the plan was conducted in three phases: Scoping, Detailed Assessment and Targeting of Management.

In the Watershed Characterization and Preliminary Findings Phase, all readily available data and information pertaining to the conditions of functions within the watershed were gathered and evaluated in detail. With that information and with thorough field reconnaissance, the primary stressors that were degrading or had the potential to degrade watershed functions were identified.

The appropriate numeric indicators to measure those stressors were determined and the assessment tools (models, GIS analyses or statistical analyses of data) best suited to predict how those indicators would react to changing watershed conditions and applications of management alternatives were selected. Once the appropriate tools were chosen, the data necessary to support their development was enumerated in a data collection plan to be implemented in the proceeding Detailed Assessment Phase of the study. In the Scoping Phase, the watershed was also delineated into smaller subwatersheds, typically one to five square miles in size.

Based on extensive input from the Local Watershed Planning Team, the following objectives emerged from the Scoping Phase for the remaining phases of the LWP study: 1) address nutrient loading and eutrophication in University Lake (local water supply impoundment located within the study area) and Jordan Lake (regional water supply reservoir subject to a pending TMDL for nutrient loading and excess eutrophication, located immediately downstream of the LWP study area); 2) improve the in-stream water quality conditions and reduce toxicity; 3) improve stream and floodplain hydrological functions within the study area; 4) improve headwater stream stability and reduce the associated sediment loading; and 5) improve aquatic habitat and riparian corridor terrestrial habitat.

In the Detailed Assessment Phase, the water quality and geomorphic data necessary to build the assessment tools was collected and those tools were developed. The tools were then used to evaluate or predict the magnitude of impacts associated with the various stessors within the study area for both existing and future conditions. Risk scores were developed to reflect the predicted or measured magnitude of impact associated with each of the stressors previously identified, and those scores were combined to calculate overall risk ratings for each LWP subwatershed. The risk rating were used in conjunction with the Local Watershed Planning Team's personal knowledge of the study area to identify subwatersheds currently experiencing the greatest functional deficits and those at the greatest risk of experiencing such deficits in the future. These high priority subwatersheds were then targeted for restoration and management efforts to address those functional losses or prevent them in the future. The most pristine areas with the highest levels of functional health were also targeted for preservation efforts.

In the Targeting of Management Phase, all feasible restoration and management opportunities within targeted subwatersheds were identified, and the assessment tools from the Detailed Assessment were utilized to measure the degree of reduction in stressor impacts that could be attributed to each project. By this means, the cost effectiveness of each option could be determined and the benefits from limited implementation resources could be optimized. The cost effectiveness projections were used in conjunction with assessments of logistical feasibility for each project and input from the Local Watershed Planning Team to establish priorities for implementation.

In the course of the LWP study, two distinct portions of the study area were identified. The first portion consisted of the more rural headwater areas of Morgan and Bolin Creeks where large areas of high quality aquatic and terrestrial habitat remained intact but historic agricultural practices caused isolated areas of stream degradation. The second distinct portion identified within the study area consisted of the more urbanized downstream sections of the two watersheds where existing and ongoing areas of development resulted in extensive areas of active stream erosion and instability along most streams within this portion. This stormwater-induced stream degradation, along with areas of riparian buffer disturbance and past hydromodifications of streams, had resulted in considerable loss of aquatic habitat and hydrologic functions in this portion of the study area. The final Local Watershed Plan for the Morgan Creek LWP study area resulted in an integrated strategy of preservation efforts and targeted stream restoration projects for the rural headwaters and an integrated strategy of stormwater BMPs and stream restoration projects for the urbanized lower portion, which is illustrated in Figure 2. The final LWP also included extensive recommendations for implementation of stormwater performance standards and development code revisions to facilitate low impact design development.

The full manuscript will describe the results from the various assessment tools with regard to predicted and measured stressor impacts, as well as the identified project opportunities in detail. The manuscript will also provide specifics on the techniques and processes used to work with the Local Watershed Planning Team to develop the project priorities and recommendations contained in the final LWP.

Document Type: Research Article

DOI: http://dx.doi.org/10.2175/193864705783865479

Publication date: January 1, 2005

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