Articles & Abstracts

The following are articles/abstracts written by members of EMB's staff and were accepted and published in magazines or presented at seminars.

For questions and inquiries about the articles/abstracts, please email Patrick Plantenberg.

Written by Joe T. Gurrieri, Hydrologist (former employee of EMB)

"Reprinted with permission from Elsevier Science"
Journal of Geochemical Exploration 64 (1998) 83-100

Distribution of metals in water and sediment and effects on aquatic biota in the upper Stillwater River Basin, Montana
J.T. Gurrieri*

Montana Department of Environmental Quality, Helena Montana 59620,USA
Accepted 21, May 1998

Abstract

The longitudinal distribution of metals and toxic effects on benthic organisms and periphyton in the upper Stillwater River basin were investigated by analyzing bed sediments, biological communities, and by conducting synoptic water quality sampling during August 1994. Methodologies employed to assess the downstream attenuation of metals and the aquatic health of the river included: (1) longitudinal water quality trend evaluation; (2) congruent element analysis; (3) sediment dispersion modeling; (4) sequential extractions on sediments; and (5) macroinvertebrate and periphyton community structure analysis. Mixing of acidic McLaren Mine drainage with alkaline waters of Daisy Creek and the Stillwater River causes rapid downstream precipitation and sedimentation of dissolved metals. The longitudinal dispersion of dissolved metals was controlled by chemical removal mechanisms immediately below the confluence of Daisy Creek and by physical dilution with clean tributary inflows further downstream. The distribution pattern of metals in sediments reflects the location, degree, and type of mineralization in the basin. Pre-mining sediment metals concentrations and the degree of anthropogenic enrichment were estimated for the Stillwater River. Macroinvertebrate and periphyton community structure exhibits a predictable response to heavy metal pollution and correlated well with sediment metals concentrations. Biological integrity was severely impaired below Daisy Creek but improved dramatically downstream with the influx of clean water and sediment from tributaries. 1998 Elsevier Science B.V. All rights reserved.

Keywords: metals; acid mine drainage; sediments; aquatic insects; Montana&

Presented by Joe T. Gurrieri at Summit 2000, GSA Annual Meeting, Reno, Nevada 

Groundwater Inflow To Rock Lake and Potential Impacts From Underground Mining, Cabinet Mountains Wilderness, Montana

In Session - Ground Water Connections II
(GSA Hydrogeology Division) November 13, 2000

Abstract

The role of groundwater in regulating the hydrology and chemistry of Rock Lake, a dilute cirque lake, was investigated during the summer and autumn of 1999 to assess the potential for adverse impacts from groundwater drainage stresses produced by underground mining. The study established that the lake is in direct communication with the local groundwater system and a large proportion of its warm season solute load is contributed by groundwater. This evidence suggests that mining induced disruptions in water and chemical budgets could compromise the aquatic ecological integrity of the lake.

After baseflow conditions were established in the watershed, non-steady water budget and chemical mass-balances for calcium, magnesium, silica, and oxygen-18 were used to estimate groundwater inflow rates over three-week time intervals. During the study, the lake changed from a system dominated by snowmelt to one influenced by groundwater. Based on water budget and solute mass-balance calculations, groundwater contributed 60% of the total seasonal inflow and 70% of the solute load. Surface inflow contributed 36% of the inflow and 25% of the solute load. Precipitation contributed only 4% of the inflow and 5% of the solute load.

The major causes of variation in the oxygen-18 composition of the lake were the seasonal change in residence time, composition of snowmelt and groundwater inflows, and enriched summer precipitation. Isotopic variables such as evaporative enrichment and atmospheric moisture composition were insignificant in comparison and had little effect on lake water composition. The small difference between lake water and groundwater composition limited the use of isotopes for water balance estimation. However, isotopes provided valuable insight into hydrologic processes not readily apparent using other methods.

Quantifying groundwater-lake interactions in a dynamic hydrologic system dominated by snowmelt is possible when both isotopic and natural solute tracers combined with the water budget are used. The non-steady mass-balance equation can be integrated over periods of time when parameters remain relatively stable. This study provides a monitoring methodology capable of identifying mining induced reductions in groundwater inflow to this and other nearby lakes.

Keywords: lakes, isotopes, mining, Montana