RP15 Assessment at Larger Scales (Watersheds, Landscape, Regional)
Thursday, 17 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(ECH-1117-768124) A Comparison of Ecotoxicological Ratings from Acid Mine-Influenced Tributaries in the Powell River Watershed, Virginia.

Echols, B¹, Cherry, D¹, Currie, R², ¹ VA Tech, Blacksburg, VA, USA² Roanoke College, Salem, VA

ABSTRACT- A three part feasibility study was conducted in the Powell River, southwestern Virginia, from 1995-2004. The purpose of this study was to identity sites within subwatersheds of the Powell River influenced by abandoned mined lands (AML). To facilitate site evaluation, an Ecotoxicological Rating (ETR) was developed to provide a single numerical score that was predictive of ecological impairment. Assessment parameters used were: (1) taxon richness, (2) % Ephemeroptera, (3) mean pH, (4) mean % clam (Corbicula fluminea) survival, (5) mean % Ceriodaphnia dubia survival, (6) mean conductivity, (7) mean % Daphnia magna survival in sediment tests, (8) mean habitat assessment, (9) sediment iron concentration, and (10) water column aluminum concentration. Ratings could range from 0-100 with sites scoring 69-60 considered moderately stressed (D rating) and those with ≤ 59 stressed (F rating). ETRs indicated that of the 141 sites evaluated, 30 were determined to be moderately stressed and 36 stressed. Sub-basins with significant impairment based upon the most failing ETRs were Ely Creek, Pucketts Creek and Crab Orchard Creek with Ely Creek having an ETR as low as 5.25. Based upon these ETRs, the US Army Corps of Engineers began remediation efforts in the Ely Creek sub-basin. The construction of two passive wetland remediation systems was completed in October 2003 and current research shows abiotic/biotic improvement below the wetland systems. Within the two remaining unremediated sub-basins, Pucketts Creek had the most impaired sites with 10 of 15 being moderately stressed to stressed. Lowest ETRs for Pucketts Creek were 13.8 and 18.0. Crab Orchard Creek also had significant impairment with five moderately stressed and nine stressed sites, with low ETRs of 24.4 and 29.5. Future remediation efforts in the Pucketts Creek and Crab Orchard Creek sub-basins will be based upon failing ETRs.

Key words: Ecotoxicological Rating, Bioassessment, AML