Pool 6 drawdown a ‘no go’

Winona, Minn. – When dealing with something as fickle as nature,
it can be difficult to make definitive plans. This summer, federal
officials had planned a drawdown of Pool 6 of the Mississippi
River, something that requires nature’s cooperation.

But earlier this month, the U.S. Army Corps of Engineers and
U.S. Fish and Wildlife Service announced those plans had been
scrapped, and that they’d try again next year to lower the water
level of the pool, which extends from Winona, Minn., to
Trempealeau, to stimulate plant growth and improve fish and
wildlife habitat.

“We had such high flows for so long that just now the river is
down to normal stages,” said Mary Stefanski, Winona District
manager for the USFWS. It didn’t help, she added, that flooding in
Iowa has affected how flow is managed in the Upper Mississippi.

The USFWS and Corps of Engineers are the primary agencies that
plan drawdowns. They’re joined by the DNRs of both Wisconsin and
Minnesota in preparing for and implementing the projects, two of
which already have been done on the Mississippi. The Pool 6
drawdown had been slated for June 16 through Sept. 30.

But late spring rains increased water flow through the pool,
delaying a drawdown and forcing another survey of the pool to
determine if “in-filling” (the placement of sediment in the river
channel by incoming water sources) would affect the required 9-foot
navigational channel.

Jeff DeZellar, project manager for the Corps of Engineers’ St.
Paul office, said the survey showed routine dredging of Pool 6 was
needed, but there were higher priorities (dredging projects) that
needed to be completed first in other pools. Bottom line: not
enough time remained this summer for a drawdown to achieve its
desired objectives.

Conditions, perhaps, will be better in 2009.

“At this time, the Corps and the partnership are planning to
conduct a drawdown in Pool 6 in the summer of 2009,” a Corps of
Engineers’ press release states. “Public meetings will be held in
the spring of 2009, and agency collaboration will continue.
Environmental documentation will be revised and made available for
public review and comment. The Corps will keep the public informed
of any decisions made.”

DeZellar said the costs associated with the Pool 6 drawdown will
include updating reports and hosting public meetings. Unlike
previous drawdowns in the river, Pool 6 will not require “advanced
dredging,” which tacked about $1 million in costs to the Pool 5
drawdown.

Stefanski said an associated cost for the USFWS is that of a
mussel survey. Concerns have been expressed in the past about the
possible negative effects of drawdowns on native mussels.
Therefore, mussels were counted in Pool 6, and will be counted
again following the drawdown. The USFWS also monitors vegetation
growth associated with drawdowns, and looks at changes in the
fishery, as well as waterfowl use of the pool.

Pool 5 was the site of the most recent drawdown, in 2005 and
2006. Pool 8 was drawn down in 2001 and 2002.

According to the Corps of Engineers, the drawdown at Lock and
Dam 6 at Trempealeau would reduce water levels at the dam by about
a foot, with up to a half-foot drawdown at Winona. It’s estimated
the drawdown would expose about 500 acres of mudflat, where
vegetation could get a fresh start. Drawdowns are meant to mimic
natural river conditions, when water levels are more variable. The
lock and dam system, while aiding navigation, has reduced that
variability.

In Pool 5, about 1,000 acres of mudflat were exposed during
drawdown; about 2,000 acres were exposed in Pool 8.

With the past two drawdowns, public access to the river, given
reduced water levels, has been a concern. Stefanski said there were
three accesses – the Trempealeau Marina, the Pla-More Campground
(Minnesota), and the Prairie Island Campground (Minnesota) – where
a Pool 6 drawdown might affect boater access. She said federal and
state officials met with campground and marina officials and
determined all accesses would be usable.

Overall, Stefanski said, drawdowns on the river are getting
“more support than anything. People ask when there will be a
drawdown on ‘their’ pool,” she said. “They’ve seen the
benefits.”

A drawdown should be especially beneficial for the lower reaches
of Pool 6, Stefanski said, as there’s limited vegetation growth in
that area.

“The water hasn’t fluctuated like a normal stream fluctuates
since the locks and dams (were built) in the ’30s.”

Stefanski said when public meetings are held next spring,
attendees will be told of plans for two years of drawdowns in Pool
6; two years are important, she said, for annual and perennial
plants to germinate, produce seeds, and flourish. Those plants are
important for fish habitat and waterfowl forage.

Federal officials rank drawdown candidates based on potential
benefits, public access considerations, and other factors,
Stefanski said. Pool 3, near Red Wing, Minn., is considered to be a
top candidate to follow a Pool 6 drawdown.

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