An Empirical Evaluation of the Performance of Different Approaches to Classifying Reference Conditions in Streams

EPA Grant Number: R828637
Title: An Empirical Evaluation of the Performance of Different Approaches to Classifying Reference Conditions in Streams
Investigators: Hawkins, Charles P. , Roberts, David W. , Stevenson, R. Jan
Institution: Utah State University , Michigan State University
EPA Project Officer: Hiscock, Michael
Project Period: January 1, 2001 through December 31, 2003 (Extended to December 31, 2005)
Project Amount: $1,499,485
RFA: Development of National Aquatic Ecosystem Classifications and Reference Conditions (2000) RFA Text |  Recipients Lists
Research Category: Aquatic Ecosystems , Water , Ecosystems


Classification of reference habitats is a critical step in bioassessment because it is used to predict the biological conditions that should occur in the absence of human-caused impairment. Our research will identify the level of classification that is optimal for bioassessment purposes by determining (1) how the sensitivity of assessments is affected by (a) the approach (regionalization versus discriminat model) used to classify habitats, (b) the autecological characteristics of organisms, and (c) the spatial scale of classification and (2) if approaches to site classification are transferable among regions. We hypothesize that the classifications that most closely approximate the local factors actually affecting individual organisms will be the best predictors of expected conditions.


All analyses will be conducted on 2 biological assemblages: algae and invertebrates. We will use a combination of existing and new data to evaluate performance of different classifications (e.g. ecoregions, catchment, type of stream reach, thermal strata) in terms of their accuracy and precision as well as their effect on the sensitivity of detecting impairment. Initial analyses will be based on a spatially extensive set of previously collected data from California, Oregon, and Washington. We will then determine how transferable our results are to other regions by replicating our analyses on independent data collected along a wide transect from New Mexico to Montana.

Expected Results:

Improving the classification of reference sites will allow water resource managers to more accurately and precisely judge the biological health of aquatic systems. Our project will also establish the most spatially extensive network of stream reference sites in the country. State and federal (US Forest Service, BLM) resource agencies will be able to immediately use these data for their own assessment programs. Finally, the reference data will provide a means for state and federal resource agencies to conduct both site and regional assessments of stream biological integrity by using our data as a reference base to interpret data collected at potentially impaired sites. The classification-indicator framework that we develop could thus serve as a model for conducting nationally comparable bioassessments.

Publications and Presentations:

Publications have been submitted on this project: View all 15 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 1 journal articles for this project

Supplemental Keywords:

EPA Regions 8 -10, CA, OR, WA, UT, NV, ID, WY, MT, CO, AZ, NM, classification, indicators, regionalization, bioassessment, EMAP, modeling,, RFA, Scientific Discipline, Geographic Area, Ecosystem Protection/Environmental Exposure & Risk, Aquatic Ecosystems & Estuarine Research, Hydrology, Ecosystem/Assessment/Indicators, Ecosystem Protection, State, Aquatic Ecosystem, Ecology and Ecosystems, Ecological Indicators, EMAP, ecological exposure, bioassessment, streams, classifying reference conditions, Oregon, ecology, classification, New Mexico (NM), stream ecosystems, anthropogenic impact, empirical evaluation, Washington (WA), modeling, environmental indicators, aquatic ecosystems, water quality, biological indicators, ecological classification, Environmental Monitoring and Assessment Program, spatial data bases, California (CA), Montana , OR

Progress and Final Reports:

  • 2001 Progress Report
  • 2002 Progress Report
  • 2003
  • 2004
  • Final