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MEMO <br /> sasr>le3sa - <br /> >a�aw�e•n�eanu • <br /> To: Craig Conroy, Burnett Cotnty Asst.Zoning Administrator <br /> From: Uriah P.Monday, PE, CFM,.MSA Professional Services, Inc. <br /> Subject: Fish Lake(T40N, R1 4M Flood Elevation Determination ' <br /> Date: October 14,20M <br /> - I <br /> The purpose of#6 memo ls.to document the methods and observaftw used to determine <br /> a 1001wr flood elevation on Fish take,located in the r a*msterly comer of T40N R14W i <br /> In Burnett County, Wisconsin. ! <br /> i <br /> Liake <br /> Hydroioav i <br /> Fish Lake is a larKHoc ked waterbody with no stream Wet or outlet, end-no overland E <br /> conrnec4ion with any of the named fakes in the surrounding area. Water levels f ctuate ` <br /> very gradually and are Influenced more.by b vAerm rainfall and snow amounts then by <br /> singular rainfM events. However, annual lake level records aro lacking and as such a <br /> statistical analysis of likely recurrence interval elevations based on hwory.cannot be <br /> conducted..To estimate the 100-year recurrence interval lake elevation in a reasonably <br /> conservative manner,the fogowing key assumpf u will be made: 1 <br /> • The TR-56 method of determining runoff volumes given a.land use and soil type will <br /> be used to Mannino a runoff curve number(RCN) <br /> • A 24-hour rainfall total of 5.7 Inches will be used <br /> • The startlng(base)lake surface elevation is derived from a historic high water mark <br /> elevation of 88.09(krcal lake datum)as measured by the Wisconsin DNR in 1984. <br /> On 10/712009, Craig CMW (Burnett Co. Zonkng) and Dan Harrington (WDNtR) <br /> transferred this elevation to a flag that was set at 29099 Brmie Road to mark the <br /> HWM. This flap elevation Is 86.20 and has been used as the aizuuting water <br /> •l nation for a flood event. This starting condillion I s k accountfar the possibility <br /> Of heavy rales o=Hft under high-waw conditions(condition per Frank Dsllem, <br /> WDNR). Note VW titre elevation corresponds to a GEOID 1996 elevation of 893.46, <br /> but no com►erelon to NAVD 88 or NGVD 29 is yet-available, therefore an <br /> tievadom heretofore referenced are to the kcal lake benchmark datum. The g <br /> 01110" M M bw*Iowa, Ililtnineepta,and Vftconsin <br /> •2901 hdo intional Lane; Subs 900, IAadbore5370-4-3133 <br /> g <br /> (606)242-7779 (800)448-0879 <br /> FAX, (ON)242-MM WES ADDRESS: www.msa-ps.00m <br /> t <br /> s <br />