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<br />OIOU-12-1995 1;:>: 11 <br /> <br />J03 <br /> <br />P.02 <br /> <br />MEMO <br /> <br />To: <br />From: <br />Subject: <br />Date: <br /> <br />Leo Lentsch, Paul Thompson, Pat Nelson <br />Jim O'Brien <br /> <br />Draft 1996 Lev~e Removal Strategic Plan <br /> <br />November 13,1995 <br /> <br />Pursuant to my phone conversation with Paul Thompson this morning, [ am faxing my <br />comments on the Draft 1996 Levee Removal Strategic Plan. There are two items 1 want to <br />address: <br /> <br />Site activity and type of flooding in Canyonlands. lbis is a site identification issue. <br /> <br />Scheduling the levee removal for 1996. <br /> <br />Item j. The nine mile study reach in the: 1995 Flooded Bottomlands investigation in <br />Canyonlands included Unr.nown Bottom, Anderson Bottom, Valentine Bottom and Queen Anne <br />Bottom which arc listed in Block 2, page 9 of the Levee Removal Plan,. It wes determin~d by <br />the hydraulic analysis that the average bankf.rll discha.rge in this reach was 39,000 cfs ....~tha <br />rerum period frequency of about 15 years. This compares unfavorably with a pre-1963 mean <br />annual peak of roughly 32,000 cfs and a post-1963 mean annWll peak 0[22,300 cfs. The <br />floodplain terrace has been disconnected from the river hydrology. In other words, overbank <br />inll.I1datioIl of the floodplain no longer occurs frequently enough to do any good. The value of <br />the sites [0 the recovery program and the focus of the study was the narrow backwater nursery <br />habitat created in five side Canyonland channels in this reach. These backwater areas are flooded <br />at lower discharges on the order 15,000 cfs. 1 don't have the numbers right in from of me. <br /> <br />With this background, my specific COmnlc:nt regarding this reach is that these sites arc nlrtural <br />sites nOl application sites. There are no construction activities that can be undertaken in this <br />reach to restore or implO\'e the overbank floodplain habitat short of cutting down all the bank <br />tamarisk and plowing the entire floodplain terrace back into the river. The floodplain is referred <br />to as a terrace because it is no longer flooded sufficiently frequently to be reworked with a <br />cbannel forming discharge. There is also nothing that needs to be done to reconstruct or restore <br />the backwater sites. I would change the label from a depression site, which can be found in the <br />Ouray reach, to a back->,,'ater habitat site. <br />