Martens Lake ready for fall activities - KWWL - Eastern Iowa Breaking News, Weather, Closings

Martens Lake ready for fall activities


After a drawdown to get rid of invasive species, the Iowa Department of Natural Resources says Martens Lake, in the Sweet Marsh Wildlife Management area, will be ready for fall recreation.

The DNR says the lake, which is a popular fishing, hunting and boating area, has been challenged by invasive aquatic plants since the mid-1990's.

In 2010, officials discovered a new invasive plant, brittle naiad.

On June 27 of this year, the DNR began a marsh drawdown to help control the spread of the plant.  They say it returned to full pool on August 3 after being more than two feet below the average full-pool level during the drawdown.

Aquatic plant specialists returned to the lake the week of August 4 found brittle naiad at seven percent of the 14 survey sites in 2011 versus 71 percent in 2010.  No aquatic herbicides were used to treat invasive plants.

The DNR began refilling the marsh on July 19 because fish were showing signs of stress caused by excessive heat.  About 100 northern pike and white sucker died between July 18 and 20 due to the heat.  They don't know if the drawdown contributed to the loss of these fish.

During the drawdown, some improvements were made to Sweet Marsh, including the installation of a larger cement water-level control structure in the southeast part of Martens Lake.  The new structure will improve water level control and increase the capacity for water flow during future drawdowns.  The DNR says flowing water carries oxygen so the new structure will help sustain fish during future drawdowns.

They also say that the removal of water from most of the areas covered by cattails in Martens Lake, stimulated the cattails to root into the ground, which should reduce the amount of floating cattails and the frequency of cattails plugging the boat-channel.

The DNR says duck hunters can expect conditions on Sweet Marsh similar to previous years during the fall.  They also say that anglers can expect typical fishing conditions through the remainder of this year.

Biologists are encouraged by the reduction of brittle naiad, but say it will take continued management over the long-term to keep the unwanted plant down to acceptable levels.

A marsh drawdown is planned for 2012 because of the results measured during 2011.

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