Stressor Identification (SI) At Contaminated Sites: Upper Arkansas River, Colorado (Final)
EPA announced the availability of the final report, Stressor Identification (SI) at Contaminated Sites: Upper Arkansas River, Colorado. This report describes a causal assessment for impairments of plant growth and plant species richness at a terrestrial contaminated site in a highly mineralized area of the Colorado Rocky Mountains. The U.S. EPA Stressor Identification (SI) methodology was used for the assessment.
This report applies the U.S. EPA Stressor Identification (SI) methodology to evaluate impairments at a terrestrial contaminated site and to shed light on its utility in such an environment. The site chosen is in a highly mineralized area of the Colorado Rocky Mountains, consisting of the 500-year floodplain and adjacent irrigated lands of the Upper Arkansas River from the confluence of California Gulch to approximately 11 miles downstream. Impairments evaluated were barren areas in the floodplain (reduced vegetation), and reduced plant growth and plant species richness in meadows irrigated with water from the Upper Arkansas River.
After a number of candidate causes were considered, the various lines of evidence support the interaction of elevated levels of extrinsic metal with decreased pH as the cause of the barren areas in the floodplain. Similar evaluation of reduced plant growth and plant species richness in the irrigated meadows leads to the conclusion that elevated levels of extrinsic metal is the cause. Aspects of the assessment process that may differ between aquatic and terrestrial systems include the critical variables that are measured, degree of development of bioassessment criteria, spatial heterogeneity and linearity of physico-chemical factors, and management practices. This project demonstrates the usefulness of the SI methodology for terrestrial systems.
This report applies the U.S. EPA Stressor Identification (SI) methodology to evaluate impairments at a terrestrial contaminated site and to shed light on its utility in such an environment. The site chosen is in a highly mineralized area of the Colorado Rocky Mountains, consisting of the 500-year floodplain and adjacent irrigated lands of the Upper Arkansas River from the confluence of California Gulch to approximately 11 miles downstream. Impairments evaluated were barren areas in the floodplain (reduced vegetation), and reduced plant growth and plant species richness in meadows irrigated with water from the Upper Arkansas River.
After a number of candidate causes were considered, the various lines of evidence support the interaction of elevated levels of extrinsic metal with decreased pH as the cause of the barren areas in the floodplain. Similar evaluation of reduced plant growth and plant species richness in the irrigated meadows leads to the conclusion that elevated levels of extrinsic metal is the cause. Aspects of the assessment process that may differ between aquatic and terrestrial systems include the critical variables that are measured, degree of development of bioassessment criteria, spatial heterogeneity and linearity of physico-chemical factors, and management practices. This project demonstrates the usefulness of the SI methodology for terrestrial systems.
Impact/Purpose
To shed light on utility of Stressor Identification at Contaminated Site
Citation
KRAVITZ, M. Stressor Identification (SI) At Contaminated Sites: Upper Arkansas River, Colorado (Final). U.S. Environmental Protection Agency, Office of Research and Development, National Center for Environmental Assessment, Washington, DC, EPA/600/R-08/029, 2011.
History/Chronology
| Date | Description |
|---|---|
| Jul 2008 | An external peer review was conducted by an independent contractor. |
| Aug 2010 | EPA revised the report based on peer review comments. |
| Feb 2011 | EPA released the final report. |
This document has been reviewed in accordance with U.S. Environmental Protection Agency policy and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.