The Savannah Harbor Expansion Project (SHEP) began in January 2015 with the purpose of deepening the Savannah Harbor federal shipping channel to allow access to larger shipping vessels (U.S. Army Corps of Engineers, 2018a). There are various features and mitigation efforts to the SHEP, one of which is the installation of a dissolved-oxygen (DO) injection system at two locations along the Savannah River to maintain pre-SHEP DO levels in the harbor (U.S. Army Corps of Engineers, 2018b). The injection systems are installed upstream near Georgia Power Plant McIntosh in Effingham County, Georgia, and downstream near Hutchinson Island, Chatham County, Georgia. Designed to maintain DO levels in the harbor as they were before deepening, the system will pull water from the river into Speece cones and inject it with oxygen before returning it to the river (Tetra Tech, 2010).
Water-quality data were measured during six days of spatial water-quality survey collection near the Georgia Power Plant McIntosh in Effingham County, Georgia and near the Hutchinson Island DO injector site in July, August, and September 2020. Water-quality data were measured at multiple locations and depths on July 23 during a reconnaissance mission near Plant McIntosh using a YSI EXO2 sonde (SN 13L100287). Water-quality data were measured on August 12, 13, and 26 using an IVER3 EcoMapper Autonomous Underwater Vehicle (AUV; SN 3086), which measures water-quality data using a YSI EXO1 sonde (herein called AUV sonde) mounted in the nose of the AUV. Water-quality data were measured on August 27 and September 10 using a YSI EXO2 sonde because the AUV was temporarily out of service. Water-quality data were logged by the AUV and EXO2 sondes at 4 and 1 hertz, respectively. Autonomous Underwater Vehicle bathymetric data were measured using an on-board depth sounder and pressure transducer. The AUV and EXO2 sondes typically were calibrated before and checked after each data collection trip per USGS water-quality sampling protocols (YSI, 2012; Wagner and others, 2006; Wilde, variously dated). Dissolved-oxygen sensor calibration checks always were completed on the day of the mission. See processing steps for additional information related to calibration and checks. Data measurements generally targeted at or near slack-tide conditions at the surface or 2-feet below the surface. Water-quality parameters measured during the surveys included: specific conductivity (microsiemens per centimeter at 25 degrees Celsius; YSI sensor 599870-01); water temperature (degrees Celsius; YSI sensor 599870-01); salinity (parts per thousand; computed from conductivity); total algae which is a dual-channel fluorescence sensor and includes phycocyanin fluorescence (relative fluorescence units; YSI sensor 599102-01) and chlorophyll fluorescence(relative fluorescence units; YSI sensor 599102-01); DO (milligrams per liter and percent saturation; YSI sensor 599100-01); pH (standard units; YSI sensor 577601); and turbidity (formazin nephelometric units; YSI sensor 599101-01)(YSI, 2012 and 2019).
References
Conrads, P.A., Journey, C.A., Petkewich, M.D., Lanier, T.H., Clark, J.M., 2018, Characterization of water quality in Bushy Park Reservoir, South Carolina, 2013–15: U.S. Geological Survey, https://doi.org/10.3133/sir20185010.
Gibs, Jacob, Wilde, F.D., and Heckathorn, H.A., 2012, Use of multiparameter instruments for routine field measurements: U.S. Geological Survey Techniques of Water-Resources Investigations, book 9, chap. A6, https://doi.org/10.3133/twri09A6.8.
Jackson, P.R., 2013, Circulation, mixing, and transport in nearshore Lake Erie in the vicinity of Villa Angela Beach and Euclid Creek, Cleveland, Ohio, September 11–12, 2012, U.S. Geological Survey, http://dx.doi.org/10.3133/sir20135198.
Ritz, G.F., and Collins, J.A., 2008, pH 6.4 (ver. 2.0, October 2008): U.S. Geological Survey Techniques of Water-Resources Investigations, book 9, chap. A6.4, https://doi.org/10.3133/twri09A6.4.
U.S. Geological Survey, 2008, Field Measurements, (edited by Wilde, F.D.): U.S. Geological Survey Techniques of Water-Resources Investigations, book 9; chap A6, https://doi.org/10.3133/twri09A6.
U.S. Geological Survey, 2019, Specific conductance: U.S. Geological Survey Techniques and Methods, book 9, chap. A6.3, 15 p., https://doi.org/10.3133/tm9A6.3. [Supersedes USGS Techniques of Water-Resources Investigations, book 9, chap. A6.3, version 1.2.]
U.S. Geological Survey, 2020, Dissolved oxygen: U.S. Geological Survey Techniques and Methods, book 9, chap. A6.2, 33 p., https://doi.org/10.3133/tm9A6.2. [Supersedes USGS Techniques of Water-Resources Investigations, book 9, chap. A6.2, version 3.0.]
Wagner, R.J., Boulger Jr., R.W. Oblinger, C.J. Smith, B.A., 2006, Guidelines and standard procedures for continuous water-quality monitors: Station operation, record computation, and data reporting: U.S. Geological Survey, https://doi.org/10.3133/tm1D3.
Wilde, F.D., 2008, Chapter A6.0, General Information and Guidelines: U.S. Geological Survey Techniques of Water-Resources Investigations, book 9, chap. A6.0, https://doi.org/10.3133/twri09A6.0.
