ENVIRONMENTAL CONDITIONS OF GREEN VALLEY LAKE

Green Valley Lake, western Indiana, has experienced periodic inputs of acid mine drainage (AMD) from the abandoned Green Valley Coal Mine. The lake serves as a state fishing area and AMD inputs may affect the aquatic ecosystem and human health. Water and bottom sediment samples were taken throughout the lake to evaluate spatial variability of contamination. Three cores were taken from the Northwest portion of the lake, where AMD enters via surface flow to evaluate temporal changes in contamination. The purpose of this research is to determine the degree and extent of present-day lake contamination.

Initial results indicate pH is slightly acidic (pH=6.4) near the locations of AMD input and increases to the east (pH=8.30). Organic matter content, based on LOI, is higher in the older portion of the lake (7-33 wt %) due to the influence of vegetation. Additionally, temperature, total dissolved solids, and dissolved oxygen decreases with depth, while salinity increases slightly with depth.

Future results are expected to show that water in the northwest portion of the lake contain elevated dissolved metal concentrations due to mixing of lake water with AMD in this area. Likewise, it is anticipated that core samples from this area will have elevated trace metals concentrations. Elevated metal concentrations could result in increased metal bioaccumulation and toxicity to organisms living in the lake. Overall, the data will provide important information for establishing the aquatic ecosystem health, particularly for organisms that live in or near the sediment-water interface where contaminants may be sequestered.