Stream discharge, sodium, bromide, and specific conductance data for stream and hyporheic zone samples affected by injection of sodium bromide tracer, Leavenworth Creek, Clear Creek County, Colorado, August 2012

Leavenworth Creek, a tributary of South Clear Creek and Clear Creek near Georgetown, Colorado contains copper, lead, and zinc concentrations that are near to or exceed aquatic life standards. The creek drains the Argentine mining district where mining was active primarily in the early 1900s. In the summer of 2012, the U.S. Geological Survey (USGS) conducted a metal-loading study using tracer dilution and spatially detailed synoptic sampling to assess the location and magnitude of copper, lead, manganese, and zinc sources to Leavenworth Creek. Sodium bromide solution was injected into the stream to facilitate calculation of stream discharge at all stream sites using the principles of tracer dilution. Consequently, concentrations of tracer (total and filtered sodium and filtered bromide) and specific conductance measured in the stream do not represent true environmental conditions because they were altered by injection of the tracer into the stream. As a result, these data are stored in the USGS National Water Information System database (NWIS) but are not accessible to the public.   
This data release contains values for total and filtered sodium and filtered bromide concentrations, where available, and specific conductance measurements for (1) stream sites sampled during the synoptic sampling event (1200 on August 30, 2012), (2) three hyporheic sniffer samplers installed in the shallow streambed, and (3) one inflow to the stream that likely represented a side channel of the mainstem. Four stream sites have additional bromide concentrations collected after synoptic sampling occurred. Streamflow discharge calculated from bromide concentrations is presented for all stream sites. In addition, automatic samplers installed at three stream sites collected samples on approximately an hourly basis for varying periods from August 27 to 30, 2012. Concentrations of filtered sodium (where available) and bromide are reported for these samples. Methods of sampling and analysis are available in Walton-Day and others (2021). 
First posted - December 28, 2020 (available from author)
Revised - August 11, 2021 
During review of the parent report for this data release, Walton-Day and others (2021), an error was discovered in the reported bromide injectate concentration. In addition, rounded bromide concentrations reported in version 1 were not sufficient to allow a user to recalculate and replicate reported stream-discharge values. Also, the values of stream discharge stored in the NWIS database and available to the public are rounded to one decimal place, which does not allow accurate recalculation and replication of the metal loading results presented in the parent report, Walton-Day and others (2021). In this version (version 2), the metadata contains the corrected concentration for the bromide injection solution; the data tables Stream_and_Sniffer_Data.csv and ISCO_Site_Data.csv contain raw data for all reported bromide concentrations; and in Stream_and_Sniffer_Data.csv, stream-discharge values are reported to two decimal places in units of liters per second and cubic feet per second to allow accurate recalculation of metal loads in Walton-Day and others (2021). Finally, in both .csv files, the U.S. Geological Survey Station ID numbers are preceded with a “T” to allow accurate input of the numbers as text by spreadsheet programs. In version 1 of the data release, the 15-digit number was changed to scientific notation during upload to spreadsheet programs, and all 15 digits were not retained.

Tags: clear-creek-county, contamination-and-pollution, environment, georgetown-colorado, inlandwaters, leavenworth-creek, mineral-resources, tracer-study, usgs-609a79cfd34ea221ce36d144, water-quality
Organization: Department of the Interior