USGS water quality data collected in 1999 identified dissolved oxygen (DO) impairments for Altamaha stream segments, and further indicated that these impairments occurred during, and were limited to, summer months, low flow and high temperature conditions. Stream flows during periods of impairment were at, or below, 7Q10 (the minimum 7- day average flow that occurs once in 10 years on the average), which is consistent with the 3- year drought experienced in Georgia from 1998 to 2000. Since the observed DO impairments were clearly driven by persistent low flows and high temperatures, occurring over several summer months, a steady state modeling approach was adopted as appropriate for DO TMDL analysis.