HR: 09:15h
AN: NB31B-04 INVITED     [Abstracts]
TI: Developing and Using Reference Condition to Assess Northern Great Plains Streams
AU: * Johnson, T
EM: johnson.tom@epa.gov
AF: U.S. Environmental Protection Agency Region 8, 999 18th Street Suite 300, Denver, CO 80202-2466 United States
AU: Angradi, T
EM: angradi.theodore@epa.gov
AF: U.S. Environmental Protection Agency Region 8, 999 18th Street Suite 300, Denver, CO 80202-2466 United States
AU: Hermann, K
EM: hermann.karl@epa.gov
AF: U.S. Environmental Protection Agency Region 8, 999 18th Street Suite 300, Denver, CO 80202-2466 United States
AU: Ismert, P
EM: ismert.peter@epa.gov
AF: U.S. Environmental Protection Agency Region 8, 999 18th Street Suite 300, Denver, CO 80202-2466 United States
AU: Selle, T
EM: selle.tony@epa.gov
AF: U.S. Environmental Protection Agency Region 8, 999 18th Street Suite 300, Denver, CO 80202-2466 United States
AU: Spaulding, S
EM: spaulding.sarah@epa.gov
AF: U.S. Geological Survey, Biological Resources Division, Denver, CO 80202-2466 United States
AB: Ideally, reference condition is represented by streams that have minimal human disturbance. In the northern plains of eastern Montana, most watersheds have been used for grazing and dryland agriculture for over 100 years. Human influence is pervasive and defining reference condition is difficult. In this study, a set of "least disturbed" sites were defined based on landscape, chemistry, and stream substrate values. All sites had some degree of human impact, but these least disturbed sites represented some of the best remaining streams in the region. Using these reference sites, condition classes (good, fair, and poor) were developed to assess the biological condition of the stream population in the region. Biological condition was determined using fish and macroinvertebrate multi-metric indices developed earlier in the study. A separate set of reference sites were also developed to determine the extent of excess sediment. The fish index found 24 percent of the stream length in poor condition and 49 percent in good condition. Using the macroinvertebrate index (applicable only to riffle habitats), 46 percent of stream length was in poor condition and 32 percent in good condition. The fish and macroinvertebrate indices, however, represented different total stream lengths. Forty-eight percent of stream length was found to be impacted by sediment.
DE: 1871 Surface water quality
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly