You are here:
BIOASSESSMENT OF WADEABLE STREAMS IN USEPA REGION 8, USING THE EMAP CHEMISTRY INDICATOR, BENTHIC MACROINVERTEBRATE INDICATOR, WATER COLUMN TOXICITY TESTS, AND SEDIMENT TOXICITY TESTS
Citation:
Klemm, D J., A. T. Herlihy, J M. Lazorchak, M. Smith, AND W T. Thoeny. BIOASSESSMENT OF WADEABLE STREAMS IN USEPA REGION 8, USING THE EMAP CHEMISTRY INDICATOR, BENTHIC MACROINVERTEBRATE INDICATOR, WATER COLUMN TOXICITY TESTS, AND SEDIMENT TOXICITY TESTS. Presented at The EMAP Symposium on Western Ecological Systems, San Francisco, CA, April 5-9, 1999.
Description:
Almost 95% of the mineralized portion of the Rocky Mountains are contained in the Southern Rockies Ecoregion. For the past century, extensive mining of metals has occurred in this area. Runoff and drainage from both active and inactive mining sites have contaminated waters and sediments. The U.S. EPA conducted a probability survey as part of its Environmental Monitoring and Assessment Program (EMAP), Regional Environmental Monitoring and Assessment Program (R-EMAP) in the Colorado portion of the Southern Rockies in 1994 and 1995. The survey targeted second-fourth order wadeable streams as represented on USGS 1:100,000 scale maps. Using data from this study, the potential impact of mining on stream condition was assessed using three approaches. The first approach used water chemistry data collected from the survey to classify streams based on Acid Neutalizing Capacity (ANC), sulfate, chloride, and metal concentrations. In the second assessment approach, water column samples and sediment samples were collected at the same sites as the chemistry samples. Ceriodaphnia dubia and Pimephales promelas 48-hour tests were conducted on the water column samples and the 7-day survival and growth tests using Hyalella azteca were conducted on the sediment samples. The third approach used stream macroinvertebrate assemblages collected at the sample sites to quantify the EMAP multimetric, Stream Benthos Integrity Index (SBII) method. High sulfate and metal concentrations in these sites served as an excellent indicator of mine drainage impacts in the watershed. The results indicated that almost all of the sites with impacted benthos and water column toxicity occurred in sites classified as mine drainage impacted by water chemistry. The stream chemistry data estimated that 28% of the stream miles in the target population were impacted by mine drainage. The toxicity data estimated that 9% of the stream miles in the target population had stream water toxic to aquatic organisms. The SBII scores indicated that 8% of the stream miles in the target population had impaired benthic invertebrate biotic integrity.