|
|
This metal-loading study was designed to determine streamflow and chemical quality at many mainstem and surface-inflow sites in a short period of time in order to create a nearly instantaneous snapshot of the loading and downstream transport of metals in the study reach. Tracer-injection methods were used to determine streamflow, and synoptic-sampling methods were used to determine chemical quality of water. Supplemental streamflow data for surface inflows were collected using conventional measuring methods.
A reconnaissance of the study reach was conducted during August 19-20, 1999, a few days before the start of the metal-loading study. The study reach included most of Daisy Creek and the Stillwater River from the mouth of Daisy Creek to the road to Lake Abundance. Although no additional metal loading was expected in the Stillwater River, this reach was included to document the extent, if any, of metal attenuation. The metal-loading study was conducted during August 24-27, 1999. Field notes from the reconnaissance are listed in table 4. Right bank and left bank are terms used in the field notes and in this report to refer to the respective sides of the stream viewed while looking downstream.
Table 4. Field description of synoptic-sampling sites, Daisy Creek and Stillwater River drainage, Montana, August 19-20, 1999 (click here for pdf file) (click here for xls file)
The tracer-injection site (fig. 2) was about 150 ft downstream from the headwater springs of Daisy Creek and 74 ft upstream from the most upstream surface inflow of acidic water. The tracer-injection site was assumed to be upstream of any metal-rich inflows that might originate from the McLaren Mine area. Downstream, sites to be sampled synoptically were selected and marked with flagging, and their distances from the tracer-injection site were measured (table 4, at back of report). Sampling sites along Daisy Creek and the Stillwater River were selected upstream and downstream from visible surface inflows. Although some streams affected by historical mining have tailings piles or other mining-related sources of metals located adjacent to the channel, these features did not exist along the study reach. Almost all visible surface inflows were selected for sampling. In some places, several inflows were channeled temporarily along the flood plain and combined into one inflow to facilitate field measurements. To detect possible subsurface inflow, additional mainstem sites were selected in longer subreaches that had no visible surface inflow. A base-flow condition absent of precipitation runoff was targeted to minimize complications of varying streamflow and short-term metal loading that might result from overland runoff from the McLaren Mine area.
Sampling sites for this study were either on the mainstem or near the mouths of surface inflows (table 4). Mainstem sites included those on Daisy Creek and the Stillwater River downstream from Daisy Creek. Inflow sites included tributaries to Daisy Creek, the Stillwater River upstream of Daisy Creek, and a tributary of the Stillwater River. Sampling-site numbers were designated according to the site’s distance in feet downstream from the tracer-injection site (fig. 2). Many surface-water sites in the Daisy Creek drainage had been sampled during previous water-quality studies (summarized by URS Operating Services, Inc., 1998). The names of these sites are listed on figure 2b and in table 4 and are noted in the text of this report.
Home page for USGS Water Resources Investigations Report 00-4261
| AccessibilityFOIAPrivacyPolicies and Notices | |
  |
|