Ammonia-N is an important part of the natural ecosystem of surface streams. Because it is readily metabolized and reacts rapidly with oxygen, the ammonia content of well oxygenated surface waters is relatively minor. Ammonia-N content of surface waters is being determined as part of a yearlong watershed assessment of two counties in west Georgia (West Georgia Watershed Assessment). Seventy sample stations are being monitored for ammonia and 20 other water quality parameters on 38 streams. Twenty-eight of these sample stations are monitored weekly; the others are collected 12 times during the year during wet and dry events. The maximum ammonia-N level of 3.8 mg/L occurs in Mud Creek. Mud Creek heads in a large cattle pasture and receives discharge of treated sewage. The next highest ammonia-N (>1 mg/L) levels are associated with runoff from farmland where cattle are fenced to have direct access to Jumpin In Creek and Yellowdirt Creek. The range of averages is 0.02 to 0.60 mg/L ammonia-N. A degree of positive correlation exists between ammonia and nitrite-nitrate-N, TKN, and total phosphorus. Ammonia-N levels in the study area are generally lower than ammonia-N concentration of the major rivers of the United States.