Ecological assessment for the wetlands at milltown reservoir, missoula, montana: Characterization of emergent and upland habitats

Wetlands in mining districts in the western United States are frequently impacted by heavy metal contaminated sediments The present study summarizes a soil contamination evaluation and an ecological assessment completed for a Superfund site located at Milltown Reservoir wetlands (MRW) in western Montana For wetlands, as well as upland habitats adjacent to wetlands, biological evaluations in the field and laboratory should be considered critical components in the ecological risk assessment process Depending upon habitat type, field and laboratory methods have been developed for hazard and risk assessment that lend themselves directly to the Superfund ecological risk assessment process, and that consider contaminant bioavailability and subtle expressions of adverse biological effects associated with chronic exposures As part of an ecological risk assessment for MRW, field surveys and a variety of biological test methods (e g., terrestrial and aquatic tests) were critical to the wetland evaluation For evaluating heavy metal effects at MRW, field and laboratory methods within the ecological assessment included wetlands delineation and preliminary plant and wildlife survey, vegetation tests in emergent and upland habitats, soil macroinvertebrate (earthworm) tests, preliminary studies using amphibian and bacterial test systems, soil characterizations, and chemical analysis of soils, sediments, and biological materials In conjunction with chemical analyses, these biological and ecological evaluations yielded an integrated evaluation of ecological effects and exposure at MRW The data gathered from laboratory and field work at MRW suggested that biological and ecological effects were subtle in their expression in the wetland In conjunction with sediment contamination evaluations, these studies should reduce the uncertainty associated with the baseline ecological risk assessment for MRW