STREAM WATER QUALITY, SEDIMENT CHEMISTRY AND MACROINVERTEBRATE POPULATION OF A STREAM DRAINING ABANDONED PYRITE AND GOLD MINES IN LOUSIA COUNTY, VIRGINIA

Contrary Creek, located in Louisa County, Virginia, is the recipient of waters draining abandoned gossen, pyrite, and gold mines. Our assessment examines the impact of the former mines on stream water quality, stream sediment chemistry, and benthic macroinvertebrates. ICP-AES analyses indicate elevated concentrations of dissolved zinc, aluminum, and iron in stream waters, confirming and updating findings of previous studies. Redox potentials measured in Contrary Creek waters range from 159 mV to 500 mV, while stream water pH ranges from < 2.0 to 6.11. Suber samplers were used to quantify the macroinvertebrate assemblage of 4 pool/riffle habitats along a 400 m reach of the stream. Dissolved oxygen, pH, redox potential, and specific conductance were measured at each habitat unit. The invertebrate assemblage was dominated by chironomid midge larvae, with hydropsychid caddisflies being the second most common taxa. We are currently investigating the relationship between chemical variables and invertebrate diversity and abundance.