Jf. Gottgens et Tl. Crisman, QUANTITATIVE IMPACTS OF LAKE-LEVEL STABILIZATION ON MATERIAL TRANSFERBETWEEN WATER AND SEDIMENT IN NEWNANS LAKE, FLORIDA, Canadian journal of fisheries and aquatic sciences, 50(8), 1993, pp. 1610-1616
Spillways at lake outlets reduce water-level fluctuations but may acce
lerate sedimentation in the lake. In eutrophic Newnans Lake, Florida,
a transect of sedimentary profiles, dared with (210)pb and Cs-137 by g
amma-ray spectroscopy, showed threefold increases in accumulation rate
s of organic matter, total Kjeldahl nitrogen (TKN), and total phosphor
us (TP) 1200 m lakeward of a spillway since its construction in 1967.
Concentrations of TKN and TP increased 3.5 and 2.4 times, respectively
, in sediments deposited since 1967. These increases were progressivel
y less at stations farther from the spillway. Postspillway accumulatio
n of TP was focused toward the dam whereas recent TKN deposition was s
imilar lakewide. Flocculent sediment (>90% water) accumulated at 1.4 c
m/yr. Dams designed to reduce water-level fluctuations may provide sho
rt-term benefits for lake access and navigation but in the long-term m
ay accelerate deposition of nutrient-rich detritus, reduce lake volume
, cloud the water, alter plant communities, and change lake productivi
ty.