Toxic Substances Hydrology Program
U.S. Geological Survey Toxic Substances Hydrology Program--Proceedings of the Technical Meeting Charleston South Carolina March 8-12,1999--Volume 1 of 3--Contamination From Hard-Rock Mining, Water-Resources Investigation Report 99-4018A
Use of Tracer-Injection and Synoptic-Sampling Studies to Quantify Effects of Metal Loading from Mine Drainage
By Briant A. Kimball, Robert L. Runkel, Kenneth E. Bencala,
This report is available in pdf format: kimball.pdf 62KB
Thousands of abandoned and inactive mines are located in environmentally sensitive mountain watersheds. Cost-effective remediation of the effects of metals from mining in these watersheds requires knowledge of the most significant sources of metals. The significance of a given source not only depends on the concentration of a toxic metal, but also on the load (or mass) of metal added to a stream. An approach that has worked well for mountain watersheds combines tracer-injection methods, to provide reliable discharge measurements on a watershed scale, with synoptic sampling, to provide spatially detailed concentration data. Multiplying concentration and discharge gives a profile of sampled instream load from which we calculate a cumulative sum of load along a study reach. Part of that cumulative total load that can be attributed to visible inflows, and another calculation gives a maximum load due to visible inflows. Comparisons of these different views of load profiles provide important characteristics of a stream that are useful for remediation planning.