Proper nitrogen (N) management as it relates to crop yield has become a critical concern due to the environmental impacts of excessive N fertilizer application. This study monitored 36 sites within the Lake Bloomington, Illinois, watershed on a weekly basis to determine nitrate-N concentrations from various surface water sources. Average nitrate-N concentrations for the period 1993 to 2002 revealed the following: agricultural production drainage tiles, 17.0 mg/L; creek water (Money Creek tributary), 12.0 mg/L; organic agriculture drainage tiles, 11.4 mg/L; surface water runoff, 6.6 mg/L; wooded pasture drainage tiles, 1.6 mg/L; and rainwater, 1.2 mg/L. In addition, as creek water passed through a small municipality ("urban effect"), [...]