Developing a Water Quality Model for FERC Re-Licensing Stakeholder Presentations

Presenting water quality data for stakeholder meetings is often challenging. Section 603 of the Energy Act requires dam owners to hold stakeholder meetings on lake water quality issues during the FERC re-licensing process. Traditionally, maps, tables, and graphs have been distributed at stakeholder meetings to present water quality data, which is often perceived as misleading and confusing. This paper presents the methodology for presenting complex water quality issues to a non-technical audience. The process used for data collection, data projection, modeling parameter selection, and modeling techniques to generate a water quality model in Lake Murray, South Carolina is reviewed. Lake Murray, South Carolina This case study involves a dam re-licensing project at the Saluda Dam on Lake Murray, South Carolina. The paper reviews data collection, data projection, modeling parameter selection and modeling techniques used to create presentation materials for FERC-required, dam re-licensing consultation meetings. Lake Murray is located in Central South Carolina and is one of the state's largest lakes. Lake Murray is approximately 78 square miles with 649 miles of shoreline. Four counties border the lake: Richland, Lexington, Newberry, and Saluda. The Saluda Dam has dammed Lake Murray since 1930 and is the source of energy for the Saluda Hydro Plant. The Saluda Hydro Plant generates power for central South Carolina. The Saluda Dam is one of the world's largest earthen dams, standing 1.5 miles wide and 208 feet high. Today, the Saluda Hydro Plant has a capability of 206 megawatts (one megawatt = one million watts). The need for quality presentation materials for stakeholder consultation meetings is based on the regulatory framework for dam re-licensing. Regulatory Framework The Federal Energy Regulatory Commission (FERC) regulates non-federal hydroelectric power projects that affect navigable waters, occupy U.S. lands, use water or water power at a government dam or affect the interests of interstate commerce. The FERC is responsible for issuing: 1. preliminary hydropower dam permits, 2. project licenses, and 3. exemptions from licensing of the nation's hydropower dams. FERC issues licenses to construct and operate hydropower dams for a term of between 30 to 50 years. Dam re-licensing is required at the conclusion of that term, and a formal licensing process involving FERC, state environmental agencies, non-government organizations, public interest groups, the public and all other stakeholders is initiated. According to FERC, the licensing pre-application and post-application filing activity is approximately seven-years. Under the licensing process, the licensee is required to engage in a pre-filing consultation period with all parties that might have an interest in, or might be affected by the project. License applicants often consult local community organizations, non-governmental organizations, tribal groups, state environmental agencies, and relevant state and federal fish and wildlife agencies for feedback regarding the impact of the reservoir dam on environmental water quality issues. The public can intervene in the licensing process anytime and ask FERC to examine issues that they feel are important, which routinely include water quality. The public can also influence the FERC's final environmental assessment of the project and how it is analyzed. The United States Environmental Protection Agency's (US EPA's) Clean Water Act explicitly states that "Any applicant for a Federal license or permit to conduct any activity including, but not limited to, the construction or operation of facilities, which may result in any discharge into the navigable waters, shall provide the licensing or permitting agency (i.e. FERC) a certification from the State." This federal law mandates that the governing State agency, such as the South Carolina Department of Health and Environmental Control (DHEC), issue a 401 Water Quality Certificate, certifying the lake's water quality prior to FERC licensing. The South Carolina DHEC considers the following conditions during a 401 Water Quality Certification review: 1. whether the activity is water dependent, 2. the intended purpose of the activity, 3. whether there are feasible alternatives to the activity, 4. all potential water quality impacts associated with the project, both direct and indirect over the life of the project. Lake Murray Model Selection Licensees traditionally distribute maps, tables, and graphs at consultation meetings to present water quality data, which is often perceived by the public as misleading and confusing. The Saluda Dam re-licensing team consisting of South Carolina Electric and Gas (SCEG), Kleinschmidt Associates, and Reservoir Environmental Management, Inc. (REMI) retained Walden Associates, Inc. (Walden) to create three-dimensional animation sequences that show water quality conditions for FERC-required consultation meetings. The re-licensing team considered chlorophyll A, temperature, and dissolved oxygen as possible modeling parameters to illustrate water quality. Dissolved oxygen was selected as the modeling parameter because it is a measure of the amount of gaseous oxygen dissolved in aqueous solution used to sustain aquatic life within the lake. Oxygen gets into the water by diffusion from the surrounding air, by aeration, and as a waste product of photosynthesis. Adequate dissolved oxygen is necessary for good water quality and sustaining life. Dissolved oxygen in surface water ranges from approximately 9.5 mg/L to 0 mg/L. Levels above 5 mg/L are considered optimal and most fish cannot survive for prolonged periods at levels below 3 mg/L. Three-Dimensional Model Goal The southeastern United States reservoir systems undergo a spring and fall turnover as a result of water temperature changes. During the summer period dissolved oxygen concentrations can drop to zero mg/L because of many factors, including temperature change and environmental factors. Project efforts were focused on illustrating the change in dissolved oxygen concentrations until fall turnover or lake mixing occurs. The goal of this project was to generate a three dimensional model of this occurrence based on existing water quality data that stakeholders can easily understand. Walden developed five, three-dimensional water quality animations to illustrate dissolved oxygen concentrations in Lake Murray. Walden in conjunction with SCEG, Kleinschmidt Associates and REMI selected a five-month sampling period that illustrates lake turnover from May, June, August, September, and October 1996 as a representation of dissolved oxygen concentrations. Five animations, approximately two to three-minutes each were generated to illustrate dissolved oxygen concentrations in the lake over this five-month period. Walden used a combination of third-party software to organize, project, interpolate, model and animate the data. Software included: ESRI's ArcView and ArcInfo for data organization and projection; C-Tech's Environmental Visualization System (EVS-Pro) for data interpolation and modeling; Adobe's Premiere 6.0 for animating; and AutoCad 2000 and Adobe Photoshop for graphic design. The animation model utilized dissolved oxygen data from sampling stations collected by SCEG and the South Carolina's DHEC. Digital elevation models (DEMs) and bathymetry data was supplied from the South Carolina Department of Natural Resources (SCDNR) and the United States Geological Survey (USGS), respectively. Animation sequences included an introduction, an overview of sampling station and landmark locations, lake cross sectional views, change in dissolved oxygen concentrations, and dissolved oxygen views from underneath the lake. Figure 1 illustrates a snapshot taken from a water quality three-dimensional animation. This snapshot shows the lake boundary and its surrounding topography, along with dissolved oxygen concentrations from May 1996. Dissolved oxygen concentrations range from 0 to 8 ppm and are displayed as red to blue in color. Figure 1 Snapshot of Water Quality Three Dimensional Animation Data Conversion Dissolved Oxygen Sampling Data Dissolved oxygen data from over 1,200 discrete sampling points at thirteen sampling stations were collected at one-meter intervals from the lake surface to lake bottom. Sampling data was supplied to Walden as thirteen excel files; one file per sampling station. Sampling data included location latitude and longitude, surface water elevation (350 feet mean sea level), date, time, sample elevation (mean sea level) and dissolved oxygen concentrations. Sampling data was then organized into five monthly files for May, June, August, September, and October. Projections were utilized to convert the latitude / longitude angles into consistent units of feet, because latitude and longitude data does not represent equal length distances or supply information regarding depth units. Walden converted each latitude / longitude coordinate into decimal degrees, then plotted the sampling locations into ESRI's ArcView. The following equation was used to convert latitude and longitude into decimal degrees. Decimal degrees = degree + (minute/60) + (sec/3600) Bathymetry and Digital Elevation Model (DEM) Data Bathymetry data was supplied as contour lines in a shapefile from USGS. Walden converted the contour shapefile into points by using a "convert polyline to point shapefile" arc script download from ESRI's website. 6,860 points were created from twenty-one contour intervals. Twelve DEMs were downloaded from SCDNR's website. The DEM's were converted to Arc INFO GRIDS. Once the conversion was completed, all twelve GRIDS were combined using the GRID "merge" command to create one seamless surface. The topographic elevation GRIDS were converted to points using the "convert polyline to point shapefile" arc script. 21,180 points were created from the DEM GRIDS. Walden removed overlapping topography and bathymetry data. Walden generated a polygon representing surface water elevation at 350 feet, and deleted all topographic points that lay within this surface water boundary. Walden then projected the bathymetry and DEM data into a common coordinate system and moved dissolved oxygen sampling data to the new coordinate system.