RESTORATION OF THE LOWER WHITEWATER RIVER

Tim Schlagenhaft.
Minnesota Department of Natural Resources, 1801 S. Oak St., Lake City, MN 55041.

During 1957 an approximately 4.5 mile reach of the lower Whitewater River was 
bypassed to allow construction of the Dorer Pools, a series of small impoundments 
managed for waterfowl in the Whitewater Wildlife Management Area.  The bypassed 
reach confined the Whitewater River between dikes, resulting in less frequent 
inundation of the flood plain which contributed to increased sediment movement into 
Weaver Bottoms, an important backwater of the Mississippi River.  At the time of 
construction, the impacts of stream channelization were not well understood.  The 
Whitewater River was suffering from intensive agricultural changes in the watershed, 
and had become wide, shallow, and too warm to support trout, and the 
channelization project was not considered to have detrimental effects.

Changes in land use in the watershed, however, slowly improved stream physical 
conditions and water quality resulting in improved fish populations.  The lower 
Whitewater River, immediately upstream of the channelized reach, now supports a 
trout population averaging 300 adults/mile.  The channelized reach, however, 
remained wide and shallow with predominately sand substrates, and supported a 
population of less than 10 trout/mile.

During 1999, the lower Whitewater River was restored to portions of its historical 
channel by diverting flow at two sites, and by constructing an approximately « mile 
"new" channel.  Stream length increased by over a mile, with slightly over 3 miles 
were converted from a channelized ditch to a natural meandering stream.  Fish habitat 
was greatly improved due to increased woody debris cover and greater diversity of 
depths and substrates in the historical channel.  Natural channel bank elevations were 
lower than the channelized portion allowing the river to inundate portions of the flood 
plain more frequently, which should increase the number of seasonal wetlands and 
reduce impacts to Weaver Bottoms by distributing more of the sediment load within 
the flood plain.

This project was experimental and was the largest stream restoration attempted in 
Minnesota to date.  Construction of the "new" channel was especially challenging, 
and resulted in a much improved understanding of stream geomorphology.  Stream 
physical conditions and fish populations will continue to be monitored.  The project 
was a cooperative effort between several DNR divisions, and was funded by the 
Minnesota legislature at a total cost of $510,000.  This project may have application 
to other tributaries of the Mississippi River.

Keywords:  flood plain, restoration, channelization, trout, Mississippi River, Weaver 
Bottoms
_________________________________________________________________________________























                           1