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<br />. <br /> <br />. <br /> <br />. <br /> <br />ATTACHMENTS <br />Attached to this memorandwn, for Board members onlv, are two docwnents, They will also be <br />presented at the Board meeting as overhead slides. They address Big Dry Creek downstream of <br />Standley Lake within the City of Westminster, The first attachment is a hydrology table, showing <br />"existing conditions" I DO-year flows vs, "future conditions" I DO-year flows, The second <br />attachment is a floodplain delineation drawing, showing the "existing conditions" I DO-year <br />floodplain delineation (in orange) and the "future conditions" IOO-year floodplain delineation (in <br />blue). The "future conditions" information included in each of these docwnents preswnes that no <br />watershed master flood protection improvements have been or are being implemented. <br /> <br />RECOMMENDATIONS <br />The staff offers the foHowing recommendations: <br /> <br />. After reading this memorandwn and viewing the brief presentation of "existing <br />conditions" vs, "future condtions" flow values, flood water surface profiles, and floodplain <br />delineations, the Board should consider the proposed designation and approval actions for <br />the three Westminster PIS', without rescinding the previous designation and approval of <br />the Westminster FHAD. <br />. In cooperation with FEMA, UD&FCD, local governments, a professional group like the <br />Colorado Association of Stormwater and Floodplain Managers (CASFM), and other <br />interested parties, the CWCB staff should either develop a State of Colorado definition of <br />"future conditions" hydrologic analyses or specifically endorse the use of the definition of <br />"foreseeable development" already in the Rules and Regulations, <br />. In the case of watersheds that are fully or mostly in one jurisdiction, both existing <br />conditions and future conditions floodplain delineations should be designated by the <br />CWCB, subject'to the agreement of the local government. <br />. In the case of watersheds that are in multiple jurisdictions, the future conditions floodplain <br />delineation, not taking into account any future basin improvements (like detention <br />facilities), should be the preferred floodplain delineation for CWCB designation, because <br />it is a more conservative floodplain delineation. The existing conditions delineation <br />should not be designated until a legal agreement between the various jurisdictions <br />adopting the watershed master plan has been approved. If the requesting cornmunity <br />demonstrates to the CWCB that it has tried unsuccessfully to negotiate such an agreement, <br />the CWCB might consider designation of the "existing conditions" delineation. <br />. The question of possibly designating watershed master plans should be explored with <br />UD&FCD, the City of Westminster and other interested cornmunities. The potential <br />value of such designation actions, the difficulties and drawbacks of such actions, and the <br />logistical and administrative issues to be addressed should all be discussed, <br />