Traveltime and reaeration measurements were made in the Salt Creek Basin, a tributary to the Des Plaines River, in northeastern Illinois during three study periods from June through October 1995. The measurements were made in representative lengths on three reaches of Salt Creek: upper reach, middle reach, and lower reach. During the measurement periods the streamflows of Salt Creek ranged from 22 to 36 cubic feet per second (ft3/s) in the upper reach, 48 to 57 ft3/s in the middle reach, and 52 to 61 ft3/s in the lower reach. Traveltimes ranged from 2.1 to 2.3, 5.3 to 6.1, and 1.4 to 1.9 hours in the upper, middle, and lower reaches, respectively. Measured reaeration coefficients adjusted to 20 Degree C ranged from 0.033 to 0.397, 0.011 to 0.036, and 0.115 to 0.306 per hour, in the upper, middle, and lower reaches, respectively. Representative measurements also were made in lengths on two reaches of major tributaries to Salt Creek, Spring Brook and Addison Creek. During the study periods the streamflows of Spring Brook ranged from 2.2 to 2.8 ft3/s and Addison Creek ranged from 9.6 to 30 ft3/s. Traveltimes for Spring Brook were 3.7 and 5.0 hours and Addison Creek was 1.6 hours. Measured reaeration coefficients in Spring Brook were 0.093 and 0.218 per hour and Addison Creek were 0.169 and 0.287 per hour.
