Project Title

IS WATER QUALITY IN BOONE LAKE A DAM PROBLEM? AN ASSESSMENT OF WATER QUALITY PRE- AND POST- DRAWDOWN

Authors' Affiliations

Annie Grant* and Dr. Ingrid Luffman Department of Geosciences East Tennessee State University Johnson City, Tennessee

Location

BAYS MTN. ROOM 125

Start Date

4-4-2018 9:40 AM

End Date

4-4-2018 9:55 AM

Name of Project's Faculty Sponsor

Ingrid Luffman

Faculty Sponsor's Department

Geosciences

Type

Oral Presentation

Classification of First Author

Graduate Student-Master’s

Project's Category

Natural Sciences

Abstract Text

Boone Lake was formed in 1952 by the impoundment of the South Fork Holston River in Sullivan and Washington counties, TN. The “V” shaped lake spans 6.88 square miles; it consists of two primary tributaries of approximately equal-length which meet just above the dam. South Fork Holston River makes up the northern arm and Watauga River feeds the southern arm. In October 2014, the discovery of a sinkhole led to detection of sediment-laden seepage under the earthen part of the dam. As a safety precaution, the reservoir was immediately lowered to an elevation of 1,352.5 feet, 10 feet below operational “winter” levels. It will remain there until the anticipated dam repair completion date of 2022. This study compares reservoir water quality data collected before seepage detection to data collected since drawdown to determine the impact of drawdown on water quality in the reservoir. Parameters analyzed were Dissolved Oxygen (DO), turbidity, conductivity (EC), Total Dissolved Solids (TDS), pH, temperature, and Escherichia Coli (E. coli). Data were compiled from two sources consisting of samples taken from 22 locations dispersed throughout each arm of the reservoir. Statistical analysis of pre/post-drawdown data was conducted using independent samples t-tests and Mann-Whitney tests as appropriate. Results of this study indicate water quality in Boone Lake has changed significantly since water levels were lowered. This change is likely due to flushing of the reservoir caused by ongoing dam repair. Conductivity, TDS, and E. coli levels have decreased significantly, suggesting improvements in water quality. Changes in temperature and pH were also found to be significant. Time series analysis of temperature and pH show significant trends overtime suggesting the lake will continue to warm and acidify. This combination of changes could negatively impact water quality, as metals trapped in lake sediments will likely become increasingly mobilized. Based on these findings, it is recommended that water quality data be collected regularly at consistent time intervals using a paired samples approach throughout the completion of the dam’s repair and continuing thereafter. Additionally, based on pH and temperature findings, it is recommended that water quality testing include testing for presence and concentrations of metals to stay vigilant to potential changes in the water column.

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Apr 4th, 9:40 AM Apr 4th, 9:55 AM

IS WATER QUALITY IN BOONE LAKE A DAM PROBLEM? AN ASSESSMENT OF WATER QUALITY PRE- AND POST- DRAWDOWN

BAYS MTN. ROOM 125

Boone Lake was formed in 1952 by the impoundment of the South Fork Holston River in Sullivan and Washington counties, TN. The “V” shaped lake spans 6.88 square miles; it consists of two primary tributaries of approximately equal-length which meet just above the dam. South Fork Holston River makes up the northern arm and Watauga River feeds the southern arm. In October 2014, the discovery of a sinkhole led to detection of sediment-laden seepage under the earthen part of the dam. As a safety precaution, the reservoir was immediately lowered to an elevation of 1,352.5 feet, 10 feet below operational “winter” levels. It will remain there until the anticipated dam repair completion date of 2022. This study compares reservoir water quality data collected before seepage detection to data collected since drawdown to determine the impact of drawdown on water quality in the reservoir. Parameters analyzed were Dissolved Oxygen (DO), turbidity, conductivity (EC), Total Dissolved Solids (TDS), pH, temperature, and Escherichia Coli (E. coli). Data were compiled from two sources consisting of samples taken from 22 locations dispersed throughout each arm of the reservoir. Statistical analysis of pre/post-drawdown data was conducted using independent samples t-tests and Mann-Whitney tests as appropriate. Results of this study indicate water quality in Boone Lake has changed significantly since water levels were lowered. This change is likely due to flushing of the reservoir caused by ongoing dam repair. Conductivity, TDS, and E. coli levels have decreased significantly, suggesting improvements in water quality. Changes in temperature and pH were also found to be significant. Time series analysis of temperature and pH show significant trends overtime suggesting the lake will continue to warm and acidify. This combination of changes could negatively impact water quality, as metals trapped in lake sediments will likely become increasingly mobilized. Based on these findings, it is recommended that water quality data be collected regularly at consistent time intervals using a paired samples approach throughout the completion of the dam’s repair and continuing thereafter. Additionally, based on pH and temperature findings, it is recommended that water quality testing include testing for presence and concentrations of metals to stay vigilant to potential changes in the water column.