Fish kill is likely on Big Eau Pleine Reservoir
WAUSAU – Low levels of dissolved oxygen in the Big Eau Pleine
Reservoir will likely cause a significant fish kill, said officials with
the state Department of Natural Resources.
DNR fisheries biologists suspect the fish kill has already started based on recent reports from ice fishermen.
Fish kills have occurred here before, typically during the late
winter months, when levels of dissolved oxygen in the ice-covered
reservoir can become too low to support game fish. A severe fish die-off
occurred in 2009, but enough fish survived to rebuild populations and
the fishery had been recovering nicely.
Beginning in late January, however, tests shows extremely low levels
of dissolved oxygen in the upstream portion of the reservoir and in the
lower portion, near the dam.
When winter thaws occur, runoff can carry nutrient-rich sediments and
organic material into the river and reservoir. As these decay, they
consume oxygen. Additionally, the buildup of organic sediments in this
aging reservoir depletes oxygen levels. At the same time, the water’s
frozen and snow-covered surface limits or prevents surface air mixing or
light penetration so that the water is not replenished with oxygen.
Since 1981, the Wisconsin Valley Improvement Company, the owner of
the dam, has operated an aeration system on the flowage. The aeration
system has provided a refuge for fish when oxygen levels are low.
However, in recent years the severity of low dissolved oxygen has
increased, especially in dry years when not enough rain falls to refill
the reservoir. Low water levels exacerbate the problem.
“In 2009 the aeration system did provide some refuge to the fish, and
although the fish kill was severe, later surveys showed a surviving
fish population capable of rebuilding the fishery,” said Tom Meronek,
DNR fisheries biologist.
“But the fish kill could be more severe in 2013, because we are
seeing much lower dissolved oxygen levels in the reservoir upstream from
Highway S than those recorded in 2009”.
By 2009, the aeration system was operating at less than optimum
efficiency. In 2010, the system was upgraded with new blower manifolds
and aeration lines. The system rebuild was funded by a grant from
Marathon County, using right-of-way mitigation fees collected from the
American Transmission Company. Additional private funds were raised
through the efforts of the Big Eau Pleine Citizens Organization.
Since the rebuild WVIC and DNR have partnered to jointly operate the aeration system and share maintenance expenses.
Dissolved oxygen levels remained stable until the end of January 2013
when WVIC monitoring started picking up low levels above and below the
aeration system. In early February WVIC and DNR agreed the aeration
system should be started about mid-February. Ultimately, the aeration
system did not reach full capacity until Feb. 22 due to a faulty seal in
one of the blower motors. This delay of one week is not significant
compared to the large volume of oxygen-depleted water entering the
reservoir.
“The aerator is not meant to handle that,” Meronek said. “It was
designed to create a fish refuge when needed. It was never meant to
aerate the entire 6,000-acre reservoir.”
In 2009, higher oxygen readings were found upstream of County S and a
larger fish refuge existed. Many fish were able to avoid the low
dissolved oxygen zone by seeking refuge upstream where favorable
conditions existed.
Currently the new aeration system is providing a small refuge area
for fish. The DNR and WVIC will continue to monitor conditions in the
reservoir.
Read more here:
FOR MORE INFORMATION CONTACT:
- Tom Meronek, DNR fisheries biologist, Wausau - (715) 359-7582
- Ed Culhane, DNR communications, Eau Claire - (715) 781-1683
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Volunteer for an active role in the Sturgeon Guard Program.
photo c. WDNR ©2013 |
New system aids in signing up sturgeon guard volunteers
OSHKOSH, Wis. -- A new online registration process is now available
for those interested in taking part in the Sturgeon Guard program. For
the past 36 years, the program has relied on volunteers to help guard
the prehistoric fish from being harvested as they head up rivers to
spawn.
“Anyone interested in volunteering can go online and pick the time,
date, and preferred location where they’d like to volunteer,” said April
Dombrowski, DNR conservation warden supervisor at Oshkosh, who headed
up the effort to create the online system. “This is really great for the
volunteers to see what opportunities are available to come out and help
protect the fish.”
The preferred spawning site location is a new feature with the
Web-based program. This is designed for volunteers that, if they have
participated in the past, can request the same spawning site location.
The Department of Natural Resources can then attempt to coordinate their
request, if fish are actively spawning at the site during their
assigned shift.
The all-volunteer sturgeon guards monitor spawning grounds 24 hours a
day throughout the spawning season, which typically runs late April to
early May. While it’s impossible to predict the exact dates spawning
will occur, guards are routinely scheduled from April 15 through May 5.
People who are interested in volunteering, are encouraged to sign up
early as spots fill quickly.
You can register online by going to our website and searching Sturgeon Guard.
Another new feature this year involves the DNR’s call center which will
now also accept registrations by phone. It is open seven days a week
from 7 a.m. to 10 p.m. at 1-888-936-7463.
Read more here.
FOR MORE INFORMATION Contact:
- April Dombrowski - (920) 424-3055
- Trish Ossmann, DNR Northeast Region public affairs manager – (920) 662-5122
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