Lower river stages affect fish, birds

Wednesday, December 19, 2012
A sand bar protrudes from the Mississippi River blocking access to the river from the Red Star boat ramp as seen on Tuesday evening, Dec. 18, 2012. According to the National Weather Service the river stage was at 5.24 feet on the Cape Girardeau gauge. (Laura Simon)

While low water levels on the Mississippi River present problems for some species within the water, some animals can thrive along sandbars and side channels that have been exposed during the drought.

"Organisms that use shallow-water areas will not have as much habitat available to them as they would if the river was at a higher stage," said Bob Gillespie, natural history biologist with the Missouri Department of Conservation's Cape Girardeau regional office.

Fish, including the pallid sturgeon, use shallow water for spawning and seek refuge there to get out of the current of the deeper water.

"When you have low river stages, juvenile fish don't have as many places to hide. If they were out in the main current, they would be swept away," Gillespie said. Low water for extended periods can affect organisms that thrive in a shallow-water habitat, but it can be beneficial for some, including the interior least turn, one of the region's rarest birds.

These birds nest on sandbar islands, so when the water is low, they have more nesting areas. When the water is high, these birds may be forced to nest inland, where they are more susceptible to predators.

The U.S. Army Corps of Engineers has incorporated environmental monitoring into its efforts to remove rock outcroppings near Thebes, Ill.

Work began Monday as crews used excavation equipment to break up and scoop out rocks restricting river traffic. The project called for crews to use explosives to blast loose the rocks, but this tactic has been delayed for now.

Fish within the shock wave can be harmed or killed.

"When we do end up blasting, we will use the smallest charge necessary to get the job done," said Mike Petersen, spokesman for the U.S. Army Corps of Engineers St. Louis District.

To drive fish out of the area immediately before blasting, contractors will employ a loud underwater noise to spook them out of the area. The corps also will have people watching for any negative environmental effects.

"If we have folks downriver who see we get fish coming up to the surface and start to see impacts, we can immediately adjust what we are doing," Peterson said.

The middle Mississippi River is approaching historic lows due to months of drought, a situation worsened last month when the corps cut the outflow from an upper Missouri River reservoir, further reducing the amount of water flowing into the Mississippi.

Dozens of lawmakers from affected states have urged the corps to restore the flow. They were unsuccessful in that effort, but they did convince the corps to expedite the rock removal, which had been scheduled to start in February.

Two excavation barges positioned on each side of a railroad bridge worked constantly Tuesday -- backhoe arms digging deep into the river bottom, pummeling rock and pulling up the remains.

"It's a lot safer, a lot cleaner and a lot faster" than using explosives, Petersen said.

Rock removal is expected to take 30 to 45 days, with explosives likely to be needed at some point -- officials just can't say when, Petersen said.

When explosions happen, sightseers expecting to view plumes of river water spraying into the air will be disappointed.

"It'll make tiny bubbles," Petersen said. "It's not going to be very exciting to see."



The Associated Press contributed to this report.

Pertinent address:

Thebes, Ill.

Map of pertinent addresses

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