Friday, July 25, 2008

Drought Conditions Intensify Across Georgia

Exceptional drought has returned to northeast Georgia, and continuing dry weather has spread drought conditions to southeast Georgia.

Although scattered thunderstorms brought some relief to drought-parched Georgia during July, allowing plants to show some recovery, the relief was localized. The rains were not enough to halt dropping stream flows across most of the state.

Many streams are at or near record low flows for late July.

Exceptional drought conditions now are occurring north and east of a line from Wilkes to Oglethorpe to Clarke to Jackson to Hall to Lumpkin to Union counties, inclusive. This includes 16 counties in northeast Georgia.

Exceptional is the worse drought category. During exceptional drought, many of the drought indicators are at levels seen only once in 50 to 100 years.

Extreme drought conditions remain in 13 counties of north Georgia: Fannin, Gilmer, Dawson, Forsyth, Gwinnett, Barrow, Walton, Oconee, Morgan, Greene, Taliaferro, Wilkes and Lincoln.
Severe drought conditions exist north and west of a line from Echols to Lanier to Berrien to Irwin to Ben Hill to Wilcox to Pulaski to Bleckley to Twiggs to Wilkinson to Washington to Jefferson to Burke counties, inclusive. This includes 96 of the 159 counties in Georgia.

In southeast Georgia, moderate drought conditions are occurring in 16 counties: Clinch, Ware, Atkinson, Coffee, Bacon, Jeff Davis, Telfair, Wheeler, Montgomery, Dodge, Laurens, Treutlen, Johnson, Emanuel, Jenkins and Screven. The 12 counties experiencing mild drought conditions are Charlton, Brantley, Pierce, Appling, Wayne, Toombs, Tattnall, Long, Evans, Candler, Bulloch and Effingham.

The six counties of coastal Georgia are classified as being abnormally dry.

Across northeast and southwest Georgia, almost all streams are at or near record low flows for late July.

Many streams are below the 7Q10 level of flow. The seven refers to the seven-day stream flow, the “Q” is quantity and the 10 refers to 10 years. Thus, the current 7Q10 level is the lowest consecutive seven-day stream flow expected to occur once in 10 years.

When stream flows fall below the 7Q10 value, there are concerns about environmental quality and a stream’s health. It is very common that stream withdrawal and discharge permits are based on 7Q10.

Streams currently at record low flows for July 24 in northeast Georgia are the Chattooga and Tullulah rivers near Clayton, the Nottely River near Blairsville, the Chattahoochee River near Cornelia and the Chestatee River near Dahlonega.

The Chattahoochee and Chestatee rivers are the main sources of water for Lake Lanier. Lanier, Hartwell and Clarks Hill reservoirs remain near or below record low levels for late July.

The Broad River near Bell and the Little River near Washington are below their 7Q10 values. The Middle Oconee River in Athens has been below its 7Q10 value for the past 6 days. However, rainfall of three to four inches in the upper reaches of the Middle Oconee’s watershed has sent a surge of water down the river. This surge should past Athens during the weekend. Without rain, the Middle Oconee at Athens is expected to return to flows levels below its 7Q10 over the weekend.

In southwest Georgia, Ichawaynochaway Creek at Milford is below its 7Q10 value while the Withlacoochee River near Quitman is at a record low flow for July 24. In southeast Georgia, the Little Satilla River near Offerman is also at a record low flow for July 24.

Area lakes are becoming dangerous as water levels drop. Unmarked obstructions are now nearer the surface and can cause boat damage. Additionally, unmarked drop-offs into deep water are appearing along the shoreline, increasing danger for casual waders and swimmers.
All boaters are encouraged to exercise extreme caution as water levels drop. Boating in the main lake channels between channel buoys decreases the danger but does not eliminate it. All boaters are encouraged to wear life jackets at all times when in an open hull boat or when above deck.
Farm ponds, especially ones not fed by springs, are showing the lack of rain. Many ponds didn’t receive adequate recharge during the winter and entered the summer low. Beef and dairy farmers are now rotating cattle from pasture to pasture not only to protect pastures but also manage their cattle drinking water supply.

Through October, Georgia’s best chance for widespread drought relief will be tropical disturbances. The heart of tropical storm season is still a few weeks away.

Visit www.georgiadrought.org for more drought information, www.georgiaweather.net for automated weather data across Georgia, www.cocorahs.org for daily rainfall from CoCoRaHS, ga.water.usgs.gov for USGS data and www.conservewatergeorgia.net for water conservation information.

(Author David Emory Stooksbury is the state climatologist and a professor in engineering and atmospheric sciences at the University of Georgia.)
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