Lakin Slough IA 04-RAC-1758

Assessment Comments

Assessment is based on August 31, 2010, Iowa DNR press release on water quality problems at this wetland.

Basis for Assessment

[NOTES:  This waterbody is not currently in Iowa's Surface Water Classification document (http://www.iowadnr.gov/water/standards/files/swcdoc2.pdf) and is thus not designated for aquatic life uses.   As such, this waterbody is classified in the Iowa Water Quality Standards (http://www.iowadnr.com/water/standards/files/chapter61.pdf) only for general uses such as livestock and wildlife watering, aquatic life, noncontact recreation, crop irrigation, and industrial, agricultural, domestic and other incidental water withdrawal uses.   According to the Iowa Water Quality Standards (Section 61.3(2)), general use waters are protected by narrative criteria designed to prevent aesthetically objectionable/nuisance conditions, and other forms of gross pollution attributable to pollution sources.

SUMMARY/EXPLANATION:  The general aquatic life uses of this wetland are assessed (evaluated) as "not supported” due to high levels of water column turbidity caused by a large population of common carp.   This high turbidity has hindered growth of beneficial aquatic vegetation such that the wetland's value as habitat for waterfowl has been severely degraded.   The following IDNR press release summarizes the water qualit impacts at this wetland:

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Lakin Slough to be Kept Dry During Hunting Season
Posted: August 31, 2010

Over the past several years Lakin Slough, in Guthrie County, has been experiencing a water quality problem caused primarily by a high number of carp that keep the water stirred up through their feeding.  This cloudy water does not allow for emergent vegetation to get established causing the slough to have mostly open water conditions that provides limited habitat for a variety of wildlife species.  

During the summer of 2010 the Iowa DNR issued a contract to dig a ditch at Lakin Slough so that the slough could be drained to remove the carp and allow aquatic vegetation to establish on the mud flats.  The variety of plant species would greatly enhance the habitat for waterfowl and other wildlife.  Unfortunately the wet summer did not allow the ditch to be completed.  The water level in the slough has not stayed down long enough to remove the carp or allow for vegetation to grow.  It will now be necessary to keep the water level low so that during the fall in order to complete the ditch and remove the carp during a winter kill.  

Keeping the water levels low into the spring and summer of 2011, vegetation will have a chance to get established and grow, depending on the weather and rainfall.  A fish barrier will be built next summer at the outlet structure to prevent carp from reentering the slough.   With the improvements to Lakin Slough the public should notice a variety of aquatic vegetation and wildlife species again using the area.  

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