While it creates some complications, the flood of 2001 shouldn't rule out the planned drawdown of Pool 8 on the Mississippi River this summer, an official with the Wisconsin Department of Natural Resources said.
"Looking at the water elevation and flows from 1965 indicate that a severe flood does not preclude a drawdown," said Gretchen Benjamin, the DNR's Mississippi River planner, referring to the year when the river hit its highest point on record.
The drawdown plan calls for slowly lowering the level of Pool 8 from La Crosse to Genoa by 18 inches from mid-June through mid-September. By reducing the water in the pool and exposing more land, the DNR hopes to re-establish native marsh vegetation in areas along the river.
The drawdown is to be only 6 inches in the La Crosse area to minimize the effect on recreational and commercial traffic.
The U.S. Army Corps of Engineers, which oversees the river's locks and dams, postponed the drawdown in 2000 because of dry conditions.
This year, the flow at Lock and Dam 8 at Genoa would have to be at or below 70,000 cubic feet per second by mid-June for the drawdown to be possible. The flow is 200,000, Benjamin said.
"We are in a wait-and-see mode at this point," Benjamin said. Officials hope to have a better indication by mid-May.
Another potential obstacle to the project is dredging, Benjamin said, which had been planned in Pool 8 this summer to keep the main channel open during the drawdown.
With the flooding, which washed additional sediment into the river, the Corps might need to do more dredging than originally planned this summer, Benjamin said. It raises the question whether it could handle the additional dredging and also do the work in Pool 8, she said.
The high water could be helpful for backwater dredging, as it makes it easier to get equipment in, Benjamin said. But if dredging is done while the water is too high, sediment could refill the dredged area.
"So this dredging will require balancing the needs of getting to the sites, dredging the materials at the right time and making sure it is all or mostly done when the actual drawdown occurs," Benjamin said.
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