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<br />:;-' '- <br /> <br />Colorado Water Conservation Board <br />Department of Natural Resources <br />721 Centennial Building <br />1313 Sherman Street <br />Denver, Colorado 80203 <br />Phone: (3031 866-3441 <br />FAX: 13031866-4474 <br /> <br />STATE OF COLORADO <br /> <br />o <br /> <br />Roy Romer <br />Governor <br /> <br />May 12, 1998 <br /> <br />James $. Lochhead <br />Executive Director, DNR <br /> <br />DariesC. Ule, P.E. <br />Director, ewcs <br /> <br />Peter H. Eva.ns <br />Acting Director, ewcs <br /> <br />Mr. Curt Parker <br />Boulder County Department of Public Works <br />Box 471. <br />Boulder, CO 80306 <br /> <br />Dear Curt: <br /> <br />I have reviewed the LOMR report sent to us on March 20, 1998 by Scott, Cox & <br />Associates, Inc. regarding the floodplain of Wonderland Creek in unincorporated Boulder <br />County. The report includes: 1) a floodplain discussion, 2) detailed large-scale "existing <br />regulatory" and "proposed regulatory" floodplain delineations through a 1200 foot long <br />reach of Wonderland Creek, 3) FEMA mapping and profile information, and 4) a formal <br />LOMR application_ <br /> <br />The LOMR application proposes to change the floodplain in a minor way and to change <br />the floodway in a significant way. The proposed changes are based on two factors: 1) <br />field-surveyed cross-sections to correct the topographic information in the current FEMA <br />study, and 2) a new hydraulic analysis. For the specific site in question, the Harr <br />residence at 2300 Emerald Road, there is essentially no change in the floodplain status. <br />The proposed floodway delineation at that site would be much farther away from the <br />existing residence (closer to the stream channel) than the current floodway delineation. <br /> <br />I would like to offer some comments on the LOMR report. <br /> <br />1) Scott, Cox & Associates confirmed that the HEC-2 information they obtained <br />from the City of Boulder was consistent with the FEMA flood elevations and the <br />FEMA floodway delineation. <br />2) There were two cross-sections in the FEMA hydraulic analysis that were repeated <br />versions of another cross-section. They were not as representative of actual field <br />conditions as new cross-sections derived by Scott, Cox & Associates from a <br />combination of field surveys and the use of the base topographic mapping from <br />the FEMA analysis. <br />3) The proposed floodplain analysis ties in very well to the current flood profile at <br />the upstream and downstream ends of the analysis. <br />