Aquatic Toxicity Monitoring

Toxicity tests have historically shown that ambient water in the headwaters of Bear Creek is sometimes acutely and/or chronically toxic and periods of toxicity generally occur when the conductivity is high (Figure 1). Because the high conductivity is thought to indicate an increase in groundwater, the increased toxicity is most likely associated with the contaminants in the groundwater.
Spatial analyses of aquatic toxicity tests did indicate that the impacts were localized in the headwaters, and water from downstream sites did not impair Ceriodaphnia growth or reproduction.

Figure 1. Ceriodaphnia survivial and conductivity in upper Bear Creek (BCK 12.4), 1988-1997.

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Last Modified: April 17, 2001