PARENT SESSION
PW11 - Site-Specific Risk Assessments
Wednesday, 20 November 2002
8:00 AM to 6:30 PM
Exhibit Hall

(P851) Hazard Assessment of Seep Waters Along Whitewood Creek, South Dakota, Using Fathead Minnow.

Buhl, Kevin^*,1, Hamilton, Steven¹, ¹ U.S. Geological Survey, Yankton, SD, USA

ABSTRACT- Mine tailings have been deposited along Whitewood Creek in South Dakota for over 100 years. When water leaches through the tailings it dissolves trace elements and carries them to the groundwater, which enters the creek at various seeps. We evaluated the toxicity of seep water from five sites to larval fathead minnow (Pimephales promelas) using 4-day static renewal exposures. Water was collected daily from three locations at each site: above the seep (reference creek water), from the seep, and below the seep (mixing zone in creek). Each water sample collected for toxicity testing was subsampled for analysis of trace elements and general water quality. Survival of fathead minnow exposed to full strength seep water and mixing zone water (87-100%) was not significantly reduced compared to that of fish in creek water (97-100%). Full strength seep water had significantly higher concentrations of arsenic at four sites and nickel at three sites compared to creek water. Conversely, creek water had significantly higher concentrations of total mercury at four sites and copper at one site compared to seep water. Concentrations of beryllium, cadmium, chromium, lead, selenium, and zinc were similar in creek and seep waters. Although these seep waters did not pose an acute hazard to fathead minnow, additional studies are needed to assess their chronic hazard potential to fishery resources in the creek. Moreover, the present study only tested 5 of the 52 seeps identified by federal and state resource agencies and it is not known what trace elements the other 47 seeps are contributing to the creek or their hazard potential to native aquatic biota.

Key words: seep water, metals, acute toxicity, fathead minnow