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. � �<<-. ,�.i .�� <br /> '.. °, . , �1�t� .;�:. _..... .�:._. <br /> �� . R,���...., .� Iq I . <br /> 1 UNIVERSITY OF MINNESOTA � Gray F�eslnvater a1O1O9�Iancestitute <br /> �x�cg�T � <br /> � � ; CoUegt oi B�ologicat Sc <br /> � TWIN CITIES <br /> � P.O. Box 100 <br /> ; County Roads 15 and 19 <br /> ': Navarre. Minnesota 55392 <br /> �` �c�c�n�1��;, <br /> D ; <br /> . ; � h�1f i 7 t�i � � � <br /> November 17, 1981 ' � •�•, . <br /> . — _....�..--. <br /> � ���TY�O� C��"� :.__ <br /> • Jean Mahusth <br /> Orono City Hall , <br /> P.O. Box 66 <br /> Crystal Bay, ht�� 55323 � <br /> Dear Jean: . <br /> I am responding to your �request for information regarding the potential <br /> harm resulting fromdredgingof channels in wetlands. I cannot precise7y <br /> predict the results because there is insufficient data to support my <br /> . conclusions. However, I think the following consequences may result from <br /> such wetland modifications. <br /> � 1 ) An open channel to the lake will result in an increased flow <br /> • of nutrients to the lake, particularly following heavy rain. <br /> 2) The filtering capacity of the wetland will be reduced and the <br /> sedimentation rate in the lake will be increased. <br /> ' s <br /> 3) The dredging will suspend nutrient rich sediments and some <br /> will reach the lake. <br /> 4) The exposure of acidic sediments that have been buried for <br /> some time will result in the release af b»ried ,nutrients to the <br /> lake. ' <br /> � 5) The opening of these channels can result in erosion of the H�etlands <br /> that should continue to fill as sediments are filtered out. The ; <br /> channels, in effect, function to drain the wetlands. <br /> Therefore, I believe that the �water and nutrient retention capacities of <br /> the wetlands will be reduced by channels dredged� through them. � <br /> Sincerely, � . . <br /> . .)�� ����� . . . . <br /> � <br /> R.S. Hanson <br /> Director, Gray Freshwater Biological Institute <br /> • RSH/d <br />