Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: THURSDAY, July 15, 1993 TAG: 9307150190
SECTION: NATL/INTL PAGE: A-7 EDITION: METRO
SOURCE: Los Angeles Times
DATELINE: TAYLOR, MO. LENGTH: Medium
Lingering floodwaters along the Mississippi's 583-mile upper branch will likely delay a speedy recovery and wreak havoc on everything from the reclamation of sunken river towns to the survival of wild grasses, say scientists and engineers girding for the impact. Unlike earthquakes and hurricanes, which spend their fury in a matter of days, the Mississippi's devastation is a quiet, invisible undermining that intensifies as long as floodwaters remain.
Mosquito and mayfly populations are already showing signs of exploding in the saturated bottomlands. River channels are filling with tons of silt. Thousands of birds are expected to stray off the Mississippi flyway during their fall migration. The risk of bacterial disease and drownings will rise among families trying to return to homes eroded by water, caked with silt and filling with river fish and poisonous snakes.
"What's phenomenal is that even after the river crests, this crisis is not over. It's just starting," said Robert Stratton, a federal animal biologist who directs the Mark Twain National Wildlife Refuge, a 275-mile-long preserve now completely underwater.
"We've got above normal rainfall predicted until September so the water will sit in some places as long as late August and September before it drains out," said Gary Dyhouse, chief hydrologist for the U.S. Army Corps of Engineers in St. Louis. "I wouldn't be surprised to see some water still around by winter."
Beneath the swirling surface of the Mississippi, the strong 15-mile-an-hour current is shaving and planing the river bottom, altering the depths of boating channels. Buoy markers have been swept away "like matchsticks," said Army Corps spokeswoman Denise Yale.
"The face of the river will change," Yale said. "Boaters will have to relearn the river. Debris is changing the shoreline. We'll get new sandbars at the bends."
The Army Corps already expects it will have to dredge some of the river's bottom to maintain the Mississippi's standard 90-foot depths. And in some flooded areas, farmers will be forced to dynamite levees to drain off standing water as the river level recedes.
Standing water has already begun to kill off all but the most durable vegetation by cutting off sunlight essential for photosynthesis.
The damage to washed-out crops is evident, already being calculated in the billions of dollars. But the bare ground that remains will also likely have a stunning impact on this fall's southern migration of teal, mallards, canvasback ducks and Canada geese, according to wildlife experts.
Normally a major flight corridor in the fall, the Mississippi's farms provide sustenance for southbound bird populations. But this year, bare fields left by the flood will drive migrating birds away from the river, say Stratton and other experts.
Decomposing animal corpses add to the disease risk in the Mississippi, already churning with sewage, farm pesticides and chemicals. Hydrologists say the massive volume of the flood has diluted the ecological risk posed by toxic runoff.
But disease risk lingers. Last week, Larry Barker, Davenport, Iowa's public health director, went out to the city's downtown flood zone to make a televised appeal to watch out for disease risks. As he spoke, he watched dead fish, rusty nail-studded boards and fecal matter float by.
"It was a graphic illustration of the problems we could have," Barker said. "I didn't even have to say anything."
by CNB