Streamflow Determination

Various techniques were used in the determination of streamflow during this study. Tracer-injection methods using changes in chloride concentrations to indicate flow volume changes described in Kimball (1997), Kimball and others (1999), Cleasby and others (2000), and Nimick and Cleasby (2001) were used for the mainstem sites. Equations used for calculating flow from downstream changes in tracer concentration are presented in Nimick and Cleasby (2001). Streamflow for all surface inflows to the mainstem, including sites in the East Fork watershed, plus selected mainstem sites were physically measured using either traditional current-meter methods (Rantz and others, 1982) or volumetrically using a calibrated collection container and stopwatch. 

For the tracer-injection part of this study, an ample supply of tracer-injection solution was prepared by mixing about 96 kg of sodium chloride (NaCl) with about 643 L of streamwater from site 0. The tracer-injection solution was sampled seven times during the study. The mean chloride concentration (89.7 ± 0.95 g/L) was used in the determination of tracer-calculated streamflow. Tracer solution was injected continuously into Miller Creek just upstream from the Black Warrior Mine tributary at a rate of 206 ± 1.5 mL/min for about 47 hours using a positive-displacement pump system controlled and monitored by an electronic data logger. The injection began at 1330 hours on August 28 and ended at 1220 hours on August 30, 2000. Three tracer-monitoring sites (T-1, T-2, and T-3) were sampled prior to the arrival of the tracer solution to determine the natural chloride concentrations (fig. 2). During the tracer-injection study, these three "tracer" sites were sampled approximately hourly to document the concentration and downstream movement of the injected chloride tracer. Samples at tracer-monitoring sites (fig. 2) were either collected manually or with automatic pumping samplers at a single point near midstream where water was well mixed. Samples were filtered though a 0.45-µm capsule filter.

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