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<br /> I�KE MINXEIONIC►
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<br /> P.O. Box 387, Wayzata. Minnesota 55391 ,���-,"" F",°
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<br /> �O�RD O/ M�N�GERS� �Y � �
<br /> �C� C� C� Ci ���C- �
<br /> Dsnd H. Coeh��n, Pitf. • Albrrl l. lehman • l�mn S pus+ell • IaAn E. ihem�t • B.rbu� Ludmund�on �f __ C • i ,
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<br /> October 23 , 1 980 �i i' �� 2 8 �� .�, I
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<br /> , ,�ITY OF OROf�O _
<br /> Mr. F:en.t Lokkesmoe , Regional Hydrologist
<br /> Dep�rtment of Natural Resources
<br /> 1200 Warner Road
<br /> JL . Paul , t,N 55106
<br /> Re : �9innehaha Creek Headwaters Control Structure
<br /> DNR Permit No. 76-62�►0
<br /> Special Provision No. X
<br /> Dear Mr. Lokkesmoe :
<br /> Pursuant to the conditions of the above referenced DNR permit
<br /> approval , please consider this letter a formal request to modify
<br /> the discharge limits of the control structure as authorized under
<br /> Sections 2 and 4 of the Gray' s Bay Dam Operational Plan .
<br /> The experience gained by the District in monitoring the behavior
<br /> of Minnehaha Creek and Lake Minnetonka , as a result of managing
<br /> flows under the current operational plan , necessitate modifica-
<br /> tion of the discharge limits at the earliest possible date .
<br /> B�sis for the Requested Modifications ,
<br /> Under Section 2 of the Gray' s Bay Dam Operational Plan no
<br /> discharge is allowed between July 1 2nd November 30 when the lake
<br /> is below a "minimum" elevation . This "minimum" elevation varies
<br /> month to month� and creates a necessity to discharge a large ' '
<br /> volume of water from the lake after freezing weather conditions
<br /> occur in order to provide storage capacity on Lake Minnetonka for
<br /> the upcoming spring snowmelt runoff , and to prevent flooding of
<br /> shoreline property.
<br /> Under freezing weather conditions , ice constrictions and buildup
<br /> occurred on the creek over the winter months of 1979-80
<br /> re�ardless of the flow rate from the lake. Therefore , main-
<br /> taining an open channel over the winter may not be feasible
<br /> contrary to previous belief. In addition , minor flooding
<br /> occurred at variou9 creek reaches over the winter at a time when
<br /> no flow from the lake occurred . Discha•rge from the lake at this
<br /> time , had it been neccessary, may have had detrimental im�acts in
<br /> the downstream communities .
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