Environment News Service (ENS)

Environment News Service (ENS)

Lowest Streamflow in 110 Years Recorded in North Carolina


Source: Environment News Service (ENS)

RALEIGH, North Carolina, August 31, 2007 (ENS) - The lowest average August streamflow in 110 years of North Carolina recordkeeping was measured last month on the Tar River at Tarboro, in the east-central part of the state.

Streamflow figures released by the U.S. Geological Survey, USGS, on Friday show that the hot, dry days of August brought record lows to many of the state’s rivers and streams amidst worsening drought conditions. People across most of eastern North Carolina are being asked to conserve as much water as they can.

The USGS and its federal, state, and local cooperators maintain 270 streamgaging stations and 39 monitoring wells throughout North Carolina.

These measurements show that the lowest average August streamflow on record occurred at 12 other monitoring stations in the state, but not compared to a 110 year period as on the Tar River.

All of these other 12 sites have at least 35 years of record, and most of the sites have more than 50 years of record. Nine of those sites are located in central North Carolina, with the others on the coastal plain or in the mountains.

August 2007 streamflows at 17 eastern North Carolina monitoring stations are lower than those measured during the 1998 - 2002 drought, when minimum streamflow records were established throughout much of the state.

Records for the lowest daily streamflow ever measured were established at three monitoring stations.

On August 17, streamflow at the Oconaluftee River, which runs through Swain County in western North Carolina, was 72 cubic feet per second, compared with the previous record low of 110 cubic feet per second established during the 1987 - 1988 drought.

During more than half of August, streamflows at this site were lower than the previous record minimum.

Record daily minimum streamflows also were established at Buckhorn Creek in Chatham County, southwest of Raleigh.

On Fishing Creek in Edgecombe County streamflow has been measured continuously since 1923, and the minimum daily streamflow measured there in August 2007 was about 2.5 times lower than the previous minimum.

Effects of the drought on groundwater levels are variable across the state, the USGS reports. Groundwater levels in unpumped wells in western North Carolina and in the outer coastal plain are approaching the levels observed during the 1998 - 2002 drought.

Groundwater levels at most locations throughout central North Carolina however, are only slightly below average for August, despite the fact that streamflows at many locations are at record low levels for August.

The heat and low streamflows also are affecting stream water temperatures, which can adversely affect fish and biological communities.

Monthly average water temperatures at 16 monitoring stations across the state averaged about three degrees Fahrenheit greater than normal for the month.

At Hyco River in Person County, where water temperature has been measured since 1985, streamflow temperatures in August were about four degrees greater than average.

Water temperatures in the sounds and estuaries also are affected. In the Neuse River at New Bern, water temperature was about 3.5 degrees higher than normal for August.

The U.S. Drought Monitoring system has classified 12 counties in the southwestern tip of the state to be undergoing the highest level of drought, called Exceptional Drought. They are Buncombe, Cherokee, Clay, Graham, Haywood, Henderson, Jackson, Macon, Madison, Polk, Swain, and Transylvania counties.

The North Carolina Drought Management Advisory Council is urging all water users in this area to limit water usage to those uses that are essential to ensure public health and safety and to prepare for the likelihood of community water systems requiring water rationing.

Maps and graphs are on the USGS North Carolina Drought Watch site.

Follow the North Carolina Department of Environment and Natural Resources Summary of Water Conservation Level Status by location at: http://www.ncwater.org/Drought_Monitoring/reporting/displaystate.php

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