Below-average March rainfall might scuttle an April experiment by the Army Corps of Engineers to send "pulses" of water down the Savannah River to encourage spawning among targeted fish species.
"It's been very dry so the jury's still out on the April pulse," said Bill Lynch, a corps representative on the Savannah River Basin Comprehensive Study Committee, which met Friday in Columbia County.
The problem, he told committee members, is that sparse rainfall throughout the upstate region has reduced recent inflows to Savannah River reservoirs to less than 10 percent of normal.
The dry weather means there might not be enough water in the lakes to channel down the river for the April 5-9 experiment, when flows were to be roughly doubled to 16,000 cubic feet per second.
The pulse experiment has been conducted once already this year - the week of March 15-19 - and the results are under evaluation, said Amanda Wrona, the director of the Savannah River project for The Nature Conservancy.
The enhanced flows - designed to mimic spring floods that once swelled the river and allowed migrating shad, sturgeon and striped bass to reach upstream spawning grounds - is a joint project by the corps and the Conservancy.
Since the existing network of dams altered the Savannah's flow, fish spawning has changed drastically, Ms. Wrona said.
"What we've seen is a decrease in the natural variability of the flows."
The Conservancy is working along the Savannah and other rivers to restore more natural flow patterns. High flows help re-nourish floodplain soils and increase seed dispersal and germination of cypress and tupelo trees.
Periodic pulses of fast water also can benefit estuaries by reducing parasites in oysters and crabs and aiding in shrimp reproduction, Ms. Wrona said.
Mr. Lynch said it will be a management decision as to whether the April pulse flows will be conducted. In the meantime, he said, the lock at New Savannah Bluff will be opened three times each week - beginning Monday - to help migrating shad, sturgeon and stripers move upstream.
The dam at New Savannah Bluff is an impediment to upstream fish migration, according to the U.S. Fish & Wildlife Service, which recommended that it be removed.
The Basin Comprehensive Study is an ongoing effort by resource agencies to devise a management plan to address the spiraling demands on the Savannah River's fluctuating water supplies.
Reach Robert Pavey at (706) 868-1222, ext. 119,
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