October 29, Monitoring Data Analysis for September 20 October 21, Gills Creek Monitoring Sites

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1 October 9, Monitoring Data Analysis for September October, Gills Creek Monitoring Sites Over the course of the monitoring period (September through October, ), an overall decrease in water temperature was observed, as well as a corresponding increase in dissolved oxygen levels at all stations. These trends are typical of fall months. Within the monitoring period, diurnal patterns in water temperature,, and dissolved oxygen were observed; these patterns were disrupted during storm events but resumed shortly thereafter. Due to the low volume of rainfall during this monitoring period, the stage at Gills Creek A was very low for two stretches of time, exposing several of the sensors to air and resulting in the data gaps observed at this station. During this monitoring period, there were a handful of notable deviations from typically observed patterns. These deviations were responsible for the maximum observed specific conductivity at both Gills Creek B and C, the minimum observed dissolved oxygen level at Gills Creek B, and the maximum level at Gills Creek C. On September nd, the specific conductivity at Gills Creek A increased rapidly and then returned to typically observed values, suggesting the occurrence of an illicit discharge. For unknown reasons, on October th, October 4th, and October th, there were three notable deviations from typical base flow conditions at Gills Creek C, all of which showed the same characteristics of a sudden increase in and specific conductivity as well as a drop in ammonium readings. The October th event resulted in the maximum observed and maximum observed specific conductivity values at Gills Creek C of 9. and.9 ms/cm, respectively. Between October 8th and October th, an unusual declining trend in water temperature was observed at all three stations. This decrease in temperature, accompanied by a slight increase in stage, was observed at all three stations and may be explained by releases from upstream impoundments. Note: ammonium data is not contained in this report because of the difficulty in maintaining the probe s calibration. However, the trends described above were observed in the ammonium data. On October 4th, the specific conductivity at Gills Creek B increased rapidly while the dissolved oxygen concentration dropped rapidly, reaching the minimum observed monthly value of. mg/l and the maximum observed specific conductivity value of.8 ms/cm. This may have been the result of an illicit discharge.

2 mg/l ms/cm NTU F Stage, ft Rain, in Continuous Water Quality Gills Creek A (Sep -- Oct, ) PARAMETER DESCRIPTION CONTINUOUS WATER QUALITY PARAMETERS: SUMMARY STATISTICS STREAM NAME: Gills Creek STAGE (FT): LOCATION: ADDRESS: Forest Drive Bridge 484 Forest Drive, Columbia, SC 96 TEMPERATURE ( F): COORDINATES: TMDL/IMPAIRMENT: 4.986, Fecal & Dissolved Oxygen TURBIDITY (NTU): 4 8 NEIGHBORING LANDUSE: APPROX. DRAINAGE AREA: Residential and commercial 48 square miles : SPATIAL LOCATION: TOTAL NO. STORMS OVER. INCH: Most upstream site SPECIFIC CONDUCTIVITY (ms/cm): MAX. DAILY RAINFALL: TOTAL RAINFALL (FOR PERIOD):.6 inches. inches DISSOLVED OXYGEN (mg/l): Stage & Rainfall Water Temp 6 Turbidity Specific Conductivity.6.4. SCDHEC in-stream standard: Daily average not less than mg/l with a low of 4 mg/l Dissolved Oxygen 4 mg/l (SCDHEC Low Standard) 9 REPORT GENERATED ON /8/

3 Continuous Water Quality Gills Creek A (Sep -- Oct, ) Explanation of Statistics: The minimum of the values recorded by the datasonde in minute intervals. The maximum of the values recorded by the datasonde in minute intervals. The median of all the values recorded by the datasonde in minute intervals. The average of all the values recorded by the datasonde in minute intervals. The standard deviation of all the values recorded by the datasonde in minute intervals. REPORT GENERATED ON /8/

4 mg/l ms/cm NTU F Stage, ft Rain, in Continuous Water Quality Gills Creek B (Sep -- Oct, ) PARAMETER DESCRIPTION CONTINUOUS WATER QUALITY PARAMETERS: SUMMARY STATISTICS STREAM NAME: Gills Creek STAGE (FT): LOCATION: ADDRESS: COORDINATES: TMDL/IMPAIRMENT: NEIGHBORING LANDUSE: APPROX. DRAINAGE AREA: SPATIAL LOCATION: TOTAL NO. STORMS OVER. INCH: MAX. DAILY RAINFALL: TOTAL RAINFALL (FOR PERIOD): Devine Street bridge 46 Devine Street Columbia, SC , Fecal & Dissolved Oxygen Residential and commercial 9 square miles Middle site.4 inches.9 inches TEMPERATURE ( F): TURBIDITY (NTU): 8 : SPECIFIC CONDUCTIVITY (ms/cm): DISSOLVED OXYGEN (mg/l): Stage & Rainfall Water Temp 8 6 Turbidity Specific Conductivity SCDHEC in-stream standard: Daily average not less than mg/l with a low of 4 mg/l Dissolved Oxygen 4 mg/l (SCDHEC Low Standard) REPORT GENERATED ON /8/

5 Continuous Water Quality Gills Creek B (Sep -- Oct, ) Explanation of Statistics: The minimum of the values recorded by the datasonde in minute intervals. The maximum of the values recorded by the datasonde in minute intervals. The median of all the values recorded by the datasonde in minute intervals. The average of all the values recorded by the datasonde in minute intervals. The standard deviation of all the values recorded by the datasonde in minute intervals. REPORT GENERATED ON /8/

6 mg/l ms/cm NTU F Stage, ft Rain, in Continuous Water Quality Gills Creek C (Sep -- Oct, ) PARAMETER DESCRIPTION CONTINUOUS WATER QUALITY PARAMETERS: SUMMARY STATISTICS STREAM NAME: Gills Creek STAGE (FT): LOCATION: ADDRESS: COORDINATES: TMDL/IMPAIRMENT: NEIGHBORING LANDUSE: APPROX. DRAINAGE AREA: SPATIAL LOCATION: TOTAL NO. STORMS OVER. INCH: MAX. DAILY RAINFALL: TOTAL RAINFALL (FOR PERIOD): Bluff Road bridge 9 Bluff Rd. Columbia, SC , Fecal & Dissolved Oxygen Residential and commercial 64 square miles Most downstream site. inches. inches TEMPERATURE ( F): 64 6 TURBIDITY (NTU): 66 : SPECIFIC CONDUCTIVITY (ms/cm): DISSOLVED OXYGEN (mg/l): Stage & Rainfall Water Temp Turbidity Specific Conductivity SCDHEC in-stream standard: Daily average not less than mg/l with a low of 4 mg/l Dissolved Oxygen 4 mg/l (SCDHEC Low Standard) REPORT GENERATED ON /8/

7 Continuous Water Quality Gills Creek C (Sep -- Oct, ) Explanation of Statistics: The minimum of the values recorded by the datasonde in minute intervals. The maximum of the values recorded by the datasonde in minute intervals. The median of all the values recorded by the datasonde in minute intervals. The average of all the values recorded by the datasonde in minute intervals. The standard deviation of all the values recorded by the datasonde in minute intervals. REPORT GENERATED ON /8/