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The hydrologic conditions for the 1999 water year for the State of Georgia were based upon the precipitation average totals from across the State and the daily mean streamflow from four "index" continuous streamflow gages operated by the U.S. Geological Survey (USGS). The precipitation data are referenced from a series of publications of the National Oceanic and Atmospheric Administration called Climatological Data-Georgia, October 1998 to September 1999, vol. 102-103. The nine divisions in these publications were averaged to three main regions: north, central, and south. The four USGS streamflow gages are: 02226000 Altamaha River at Doctortown, GA, 02317500 Alapaha River at Statenville, GA, 02347500 Flint River near Culloden, GA, and 02392000 Etowah River at Canton, GA.
For the 1999 water year, the average precipitation total statewide was 39.77 inches, which represents a deficit of 11.78 inches. The south region recorded the highest average precipitation deficit of 12.71 inches, with the extreme southwest division recording a deficit of almost 17.00 inches. This area was considered in extreme drought conditions throughout the 1999 water year. All four of the index gages recorded deficient mean streamflow conditions for at least ten months of the year. The Flint River at Culloden and Alapaha River at Statenville gages recorded extremely low monthly streamflows, verifying the drought conditions in the south region of Georgia.
During October, all regions of the State recorded below normal precipitation totals. The departures from normal ranged from -0.99 inches in the south region to -1.56 inches in the north region. The Etowah River at Canton gage was in the near-normal range for the month, while Alapaha River at Statenville gage recorded only a third of the normal monthly mean streamflow. The near-normal streamflow on the Etowah was a result of previous precipitation, while the Alapaha continued in dry conditions from previous months.
For November, all regions again recorded below normal precipitation totals. The larger departures from normal switched, however, from the north to the central and south regions. All streamflow gages were in the deficient range, with even the Etowah River gage at only 75 percent of normal. These trends would continue through December.
During January, the entire State recorded average precipitation totals slightly above normal. The departures from normal ranged from +0.34 inches to +0.55 inches. This was not enough rainfall to reverse the deficient streamflow conditions at all four index gages. The Altamaha River at Doctortown gage was at approximately one-third the normal monthly mean streamflow.
From February through May, below-normal average precipitation totals were recorded in all regions of Georgia. During this period, only the Alapaha River at Statenville gage recorded normal streamflow conditions during the months of April and May. This reflects the smallest rainfall deficit that occurred in the southeast division of the State.
For June, average precipitation totals were above normal across the State. The departures from normal ranged from +1.75 inches to +2.08 inches. This increased precipitation was caused by tropical activity. The above normal precipitation was again not enough to affect the monthly mean streamflow at all four index gages. All four gages recorded less than one-third the normal streamflow for the month.
From July through August, the dry conditions resumed with all regions of the State recording below-normal average precipitation totals. All streamflow gages recorded deficient monthly mean streamflows for July and August.
During September, above average precipitation totals occurred in the central and south regions of Georgia. The north region persisted in dry conditions with a departure from average of -1.51 inches. These precipitation conditions were reflected in the monthly streamflow records. The Flint River at Culloden gage recorded normal monthly mean streamflow conditions and the Alapaha River at Statenville gage was nearly 600 percent above normal. The Altamaha and Etowah gages remained below normal for the month.