A new report by the USGS finds that "backwaters may represent a sink for organic matter that enters from the main channel and that stable discharge, by lengthening water turnover times, will likely increase organic matter retention." [right, cover photo from USGS report]
Ref: Behn, K.E., Kennedy, T.A., and Hall, R.O., Jr., 2010, Basal resources in backwaters of the Colorado River below Glen Canyon Dam; effects of discharge regimes and comparison with mainstem depositional environments: U.S. Geological Survey Open-File Report 2010-1075, 25 p.