PARENT SESSION
Oral Session #73: Applied Ecology and Ecological Economics. Presiding: J. Hof.
Friday, August 10, 2001. 8:00 AM to 12:00 PM. Hall of Ideas P&Q.
The ecological impacts of dam mitigation: The TVA's RRI program.
BEDNAREK, ANGELA1, 1
ABSTRACT- Degraded tailwater conditions within the Tennessee River system prompted the Tennessee Valley Authority (TVA) to make modifications to the structure and operations of their dams in 1991 through the Reservoir Releases Improvement Program (RRI). These changes were implemented to reach certain levels of dissolved oxygen and discharge based on hypothesized responses from river organisms. I extended preliminary TVA analyses by testing statistical hypotheses using analyses of variance to assess the response of the biological community to the modifications. I utilized long-term data collected by the TVA, which included yearly monitoring of the benthic macroinvertebrates in each of ten tailwaters. Overall, total macroinvertebrate abundance and taxa richness were significantly higher in the set of years following the increases in DO and discharge. Water-quality sensitive taxa, such as caddisflies, increased significantly in abundance at most of the dams following RRI. Though tolerant taxa, such as oligochaetes, also increased after the RRI changes, their proportion of the total macroinvertebrate abundance did not change. The results suggest that tailwater environmental conditions have improved enough to increase the abundance of most organisms but no single group of macroinvertebrates is driving the response. The intent of these analyses is to discover the types of river conditions necessary to support enhanced biological communities in the Tennessee River system and improve tailwater management.
KEY WORDS: dam mitigation, tailwaters, TVA