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Implications of Changes in Riparian Buffer Protection for Georgia's Trout Streams |
Researchers: Judy L. Meyer, Krista L. Jones, Geoffrey C. Poole, C.
Rhett Jackson, James E. Kundell, B. Lane Rivenbark, Elizabeth L.
Kramer, and William Bumback
This four-year research project by scientists at the University of
Georgia and Eco-metrics evaluated the impacts of Georgia House Bill
1426 on the State's trout streams. The study's objectives were to provide
the State with scientific information on: 1) the effectiveness of
100- vs. 50-ft riparian buffer widths in protecting trout habitat in
North Georgia's streams; and 2) the
geomorphic and biological characteristics of headwater trout streams that are exempt from 50-ft riparian buffer requirements.
Objective 1: Effectiveness of 100- vs. 50-ft buffers  Study conceptual model
Elevated
stream temperatures and increased delivery of fine sediment to streams are two potential consequences of reducing the
buffer width (Barton and Taylor 1985, Gregory et al. 1991, Waters 1995,
Scott et al. 2002, Pusey and Arthington 2003). Both warm water
and fine sediment can adversely affect the metabolism, growth, and
reproductive success of trout (Hausle and Coble 1976, Crisp 2000, Curry
and MacNeill 2004, Suttle et al. 2004). Thus, a simple conceptual
model of land-use effects on trout populations guided our
research.
To assess the adequacy of 15-m buffers, we
developed a spatial database of Georgia’s trout stream network,
identified more than 40 sampling locations that represented the range
of landscape conditions within the trout stream network, and collected
field data on instream habitat and trout populations at these sampling
locations. Using these data, we: 1) quantified the three
equations describing the relationships between riparian forests,
instream habitat, and trout; and
2) predicted the expected adequacy of
15-m riparian buffers
for supporting self-sustaining trout populations
at the
stream segment and stream network scales.
Objective 2: Characteristics of headwater trout streams
Headwater trout streams with average discharge of 25 gallons per minute
(gpm) (0.057-cfs) or less are exempt from 50-ft riparian buffer
requirements and can be piped up to 200 ft by individual
landowners. For this part of the study, Rhett Jackson
and Lane Rivenbark researched: 1) the size of watersheds generating
streams with mean annual discharge of 25 gallons per minute; and 2) the
applicability of drainage area, average monthly baseflow, or channel
metrics as accurate surrogates for average discharge measurements in
small ungaged basins. To provide this scientific information,
they related average discharge and drainage using continuous flow data
from sixteen small streams in the Southern Appalachians and completed
field surveys of 30 streams for the points of channel and perennial
flow initiation.
Based on the relationship between basin area and mean annual discharge
observed by Jackson and Rivenbark, we estimated the extent of the
landscape drained by these streams that can be piped under existing
riparian buffer regulations. Also, the biological impact of
piping headwater trout streams was assessed by the comparison of
macroinvertebrate drift samples collected from 3 streams sampled by Jackson and
Rivenbark and 1 piped stream.
See the study's executive summary and final report for more information and results.
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Research 
