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<br />longer drawdowns may allow woody <br />cover, such as willows, to become estab- <br />lished. Annual seed plants can be encour- <br />aged by annual, partial drawdowns. The <br />timing of annual drawdowns is very impor- <br />tant in determining what species of plants <br />germinate and grow. Maintaining good <br />growths of aquatic food plants, such as <br />sago pondweed, is more difficult and nor- <br />mally requires very careful water manage- <br />ment over a period of several years. The <br />timing of a drawdown is also important <br />since you may adversely affect some <br />marsh animals during their breeding <br />season. <br />Water management may also be <br />used to create open water areas in <br />marshes that are overgrown with exces- <br />sive vegetation. Spring flooding and <br />gradual lowering of water levels over the <br />main growing period can result in the <br />thinning of the vegetation to create better <br />wildlife habitat. Flooding a marsh for one <br />or more entire growing seasons may be <br />necessary to open some dense stands of <br />cattail or to thin an overabundance of <br />woody vegetation. <br /> <br />Water level management can also be <br />used to influence the type of wildlife and <br />fish use that occurs on a wetland. Lower- <br />ing water levels may help to control popu- <br />lations of rough fish, such as carp. On the <br />other hand, increasing water depths in the <br />spring may provide spawning habitat for <br />other fish, such as northl3rn pike. In north- <br />ern areas increasing water level in the fall <br />and winter may be necessary to insure <br />that muskrats have sufficient water to <br />continue their activities below the ice. <br />In general, the management of water <br />levels in a wetland is done to produce a <br />diversity of habitat for wildlife and a good <br />interspersion of open water and vegeta- <br />tive cover. <br /> <br /> <br />19 <br />