RESPONSE OF STREAM BIOTA TO ACID NEUTRALIZATION VIA LIME DOSING

In the spring of 2004 an Aqua-Fix® lime doser was installed to neutralize acid loads (786 lbs/day) from an abandoned underground coal mine in Carbondale, Ohio. A previous passive treatment attempt with vertical flow wetlands reduced iron levels significantly but did not reduce acidity levels to promulgate stream biota recovery in receiving stream, Hewett Fork. As a result of lime dosing, the treatment site currently loads 683 lbs/day of alkalinity to the receiving stream instead of acidity. However, iron loads increased to pre-passive treatment levels due to removal of wetland cells. With lime dosing, increases in alkalinity and pH stimulated return of aquatic life in Hewett Fork. Fish and macroinvertebrates increased in diversity and abundance throughout Hewett Fork with the greatest recovery occurring at the furthest distance from the doser. Full recovery of aquatic life occurred in the lower four miles of stream, which now attain Ohio EPA biological criteria for Warm Water Habitat. Complete aquatic life recovery is limited by variable water quality conditions due to untreated acid sources, total metal concentrations, and habitat related impairments.