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The State of Tennessee derives many benefits from an abundance of streams, rivers, and lakes. Excluding the Mississippi River, which flows south along Tennessee's western boundary, the largest rivers in the State are the Tennessee and Cumberland Rivers. The Tennessee and Cumberland Rivers are highly regulated by an extensive system of multipurpose dams and reservoirs. Natural conditions generally only occur in tributaries to the major rivers or other streams draining relatively small basins throughout the State. Streamflow data from these unregulated streams can be used to describe hydrologic conditions across the State.
A comparison of annual mean discharges for the 2000 water year with means for the period-of-record for unregulated streams indicates that runoff during the water year was significantly below average across the entire State. Discharge data from unregulated streams in East and Middle Tennessee (east of Kentucky Lake on the Tennessee River) averaged only about 53 percent of the means for period-of-record. In West Tennessee, annual mean discharges averaged only about 45 percent of the means for the period-of-record. Monthly mean discharges were below period-of-record means for most of the water year throughout the State. Monthly mean discharges approached or exceeded the long-term mean values only for the months of April and May.
There were no significant flood events recorded at USGS streamgages in Tennessee during the 2000 water year.
Ground-water levels at key aquifers throughout Tennessee were affected by rainfall during the 2000 water year. Ground-water levels are recorded continuously at a series of observation wells across the State. Water levels recorded from wells throughout Middle and East Tennessee generally respond faster with larger fluctuations than wells drilled into the sand and gravel aquifers of West Tennessee. Observation wells in Shelby County show that ground-water levels are strongly affected by ground-water withdrawals by the City of Memphis and surrounding communities. At well Sh:Q-1, near downtown Memphis, water levels declined steadily since 1972, although a slower rate of decline began in 1988. The decline in ground-water levels in the Memphis area is not indicative of a reduction in the available ground-water supplies, but the response of the aquifer to additional withdrawals.
Water-quality data were collected at 29 surface-water sites and 19 ground-water
sites during the 2000 water year. About half of these sites are located in the
Tennessee River Basin and were sampled as part of the U.S. Geological Survey's
National Water-Quality Assessment (NAWQA) Program. Data for pesticides in surface
water were collected at four NAWQA sites. Other water-quality activities included:
The data collected for NAWQA sites identified low-level concentrations of pesticides in surface and shallow ground water. Fecal indicator bacteria exceeded 1,000 colonies per 100 milliliters in at least one sample collected at each of the NAWQA surface-water sites that were sampled monthly.
Friday, 13-Apr-01 14:34:11 CST
This abstract can be cited as follows:
Hampson, P.S., 2001, Hydrologic conditions in Tennessee, water year 2000 [abs.], in Tennessee Water Resources Symposium, 11th, Burns, Tenn., 2001, Proceedings: Tennessee Section of the American Water Resources Association, p. 1B-9.
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