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2. Adverse Flood Impacts and Durability <br />The CWCB takes very seriously the flood safety aspects of RICDs, and will carefully <br />consider flood safety in reviewing whether an RICD has been proposed for an <br />appropriate stream reach. The CWCB recommends that an applicant for an RICD <br />demonstrate, through appropriate technical analyses, that the proposed boating course <br />is designed and will be (is) constructed in such a manner as to: <br />Adequately pass all flows up to and including the 100 -year (1% probablity) flood <br />flow without causing adverse impacts to upstream, downstream or adjacent <br />property owners. Verification of "no adverse impact" can be demonstrated <br />through the use of a CWCB approved step- backwater hydraulics model such as <br />HEC -RAS. 1 <br />Adequately withstand stream forces for the design life of the proposed <br />recreational facility for all flows up to and including the 100 -year flood so that <br />damage and failure of the boating course is avoided. Several people suggested <br />removing this bullet. <br />3. Liability <br />The CWCB assumes no responsibility for use or misuse of the boating course and is not <br />subject to liability for injuries or damages caused therefrom. CWCB approval of or <br />recommendation to endorse an applicant's proposed RICD water right in no way implies <br />1 As required by current federal regulations and state floodplain management rules (not new guidance <br />developed for the purposes of this document), the applicant is advised that the proposed boating facility <br />must be analyzed for flood impacts by modeling the "existing conditions" (pre - facility) scenario and the <br />"proposed conditions" (with - facility) scenario. The hydraulic computer modeling must be performed by a <br />registered Professional Engineer (Colorado Registration) having expertise in surface water hydraulic <br />modeling. Impacts that should be analyzed include increases in water surface elevations for the range of <br />flows experienced at the proposed recreational facility, but especially the 100 -year flood event. <br />According to federal regulations, water surface elevations at the proposed RICD facility may not increase <br />at all (zero rise) in the event that the proposed recreational facility is within a stream reach having a <br />designated Floodway (the most hazardous portion within the 100 -year floodplain). For reaches that are <br />not within a designated Floodway, any increases in the 100 -year flood profile for the proposed RICD <br />facility (up to a maximum of one foot or a lesser amount specified by local floodplain ordinances or codes, <br />whichever is more restrictive) must be documented. Proper notification of adverse impacts (increased <br />water surface elevations) must be provided to affected property owners and a Letter of Map Revision <br />(LOMB) should be obtained as required by FEMA for National Flood Insurance Program purposes. <br />2 It is recommended that the boating course consist of appropriate materials and installation to endure <br />velocities, shear stresses, other erosive conditions, sedimentation, and debris that would be experienced <br />over its design life, and during high flow (flood) conditions. For example, a boulder drop structure should <br />be constructed with material having suitable size, hardness, shape and gradation and should be installed in <br />such a manner that it is anchored into the stream bank and streambed to survive long -term operation and <br />flood events. Proper durability of the facility will assist the applicant in avoiding costly repairs and <br />maintenance, and may help to avoid possible abandonment of the RICD water right in the future. <br />2 <br />