Fixed-station water-quality monitoring at Congaree National Park: Data Summary 2011

Gregory, M.; Rinehart, Aaron; Wright, Wendy

doi:10.36967/2193850

In 2006 Congaree National Park (CONG), in conjunction with the Southeast Coast Network (SECN) Inventory and Monitoring Program, began collecting water-quality data at Cedar Creek as part the NPS Vital Signs Monitoring Program. The continuous monitoring data station is located approximately one mile south of the visitor center and collects water temperature, dissolved oxygen, pH, salinity, specific conductance, turbidity and water-level data every 30 minutes following the methods of Wenner and Geist (2001). This publication summarizes data collected from January 1, 2011 to December 31, 2011. The CONG fixed-station water-quality monitoring site is part of the SECN water-quality monitoring program, which collects data in the vicinity of eight parks located along the southeastern U.S. coast (DeVivo et al. 2008). Information collected by this monitoring program may be used to help park managers make better-informed decisions by understanding trends and variability related to water-quality conditions in park waters. Summary data are presented in annual data reports published by the SECN. Significant findings for 2011 are as follows: The 2011 continuous data record includes several periods of flagged data, primarily due to equipment malfunctions. Dissolved oxygen values were the most often flagged parameter. Water temperature ranged 1.6–30.5°C (34.88–86.9°F). The lowest monthly average temperature of 6.0°C (42.8°F) occurred in January, and the highest monthly average of 28.2°C (82.76°F) occurred in July. Specific conductance values ranged from 21 to 70 µs/cm. The baseline level for specific conductance in Cedar Creek is approximately 25 µs/cm. A majority of spikes in specific conductance were associated with rain and/or runoff events. A period of elevated specific conductance was noted during the first week of April and coinciding with near-bankfull flows on the Congaree River indicating possible backwater effects at the station. Dissolved oxygen concentrations ranged from a low of 4.7 mg/L in July to 11.1 mg/L in February. Forty-one individual readings were below 5.0 mg/L, but only one daily average was lower than the South Carolina freshwater standard of 5.0 mg/L; the daily average dissolved oxygen reading for July 22 was 4.98 mg/L. The lowest monthly average was in June (5.1 mg/L) and the highest monthly average was in January (10.6 mg/L): however, only 2% of readings were used during the month of January (the remaining data were flagged). The next highest monthly average was observed in December (9.8 mg/L) where 63% of the readings were used. pH values ranged between 5.6 and 6.6, with 55% of measurements (5,839/10,595) below the South Carolina standard of 6.0 for freshwater. The lowest monthly average for pH was 5.9, occurring in May, August, September and December. The highest monthly average was 6.2 in January. Elevated pH values were noted during the first week of April due possibly to backwater from the mainstem of the Congaree River during a high flow event. Turbidity values were generally low in Cedar Creek throughout much of the year. Elevated mean daily turbidity values above 50 NTUs (the South Carolina turbidity standard for freshwater) were observed six times during 2011, with all exceedences occurring during, and after, summer rainfall events. The lowest monthly average for turbidity was 2.1 NTUs in January, and the highest monthly average was 22.8 NTUs in June.

Fixed-station water-quality monitoring at Congaree National Park: Data Summary 2011

Series

Collections