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COLORADO FLOODPLAIN & STORMW ATER CRITERIA MANUAL . OPERATING PRINICIPLES Approved July 21, 2004 OPERATING PRINCIPLE #1- CRITERIA MANUAL DISCREPANCY RESOLUTION The CWCB recommends that government entities in Colorado adopt the statewide manual at their own discretion, wholly or in part, depending on the needs of the adopting agency. Each entity adopting the contents of the statewide manual is responsible for enforcement of the manual within its jurisdictional boundaries. In the event that conflicts arise between the statewide manual and other drainage manuals, the manual adopted by the entity that has jurisdiction over the subject area will govern. OPERATING PRINCIPLE #2 - NEW AND REVISED FLOODPLAIN DELINEATIONS All new and revised floodplain delineation studies within the state of Colorado should be prepared in accordance with the Colorado Water Conservation Board (CWCB) "Rules and regulations for the designation and approval of floodplains and of storm or floodwater runoff channels in Colorado". The floodplain delineation criteria presented in the statewide manual are the technical guidelines of the CWCB rules and regulations. OPERATING PRINCIPLE #3 - REGULATORY 100-YEAR FLOODPLAINS The 100-year floodplains delineated by detailed or limited methods are considered to be the regulatory floodplains of the storm or floodwater runoff channels in Colorado as defined in 37-60-106, Colorado Revised Statues (CRS). . OPERATING PRINCIPLE #4 - DESIGNATED FLOODW A YS The CWCB recognizes that designated floodways are administrative limits and tools used by communities to regulate existing and future floodplain developments within their jurisdictions. Therefore, communities may choose to delineate floodways based on FEMA's I-foot rise criteria or based on more strict criteria by allowing a lesser amount of rise above the base flood elevations. The CWCB floodway operating principle is synonymous with communities' adopted floodway criteria. Where no local floodway criteria exist, the CWCB recommends the use of the minimum FEMA standard. OPERATING PRINCIPLE #S - HYDRAULIC STRUCTURES The CWCB recommends that government entities in Colorado adopt the design standards presented in the statewide manual for hydraulic structures. The criteria presented in the statewide manual are considered to be minimum standards. However, government entities may adopt higher design standards if they so desire. It is recommended that design and construction of hydraulic structures that are considered for full or partial funding by the CWCB be prepared in accordance with the guidelines presented in the statewide manual. The construction of new or modified hydraulic structures should not adversely impact adjacent properties without due process as required by FEMA regulations and CWCB Rules and Regulations. OPERATING PRINCIPLE #6 - HYDROLOGY The CWCB operating principle is to present hydrologic methods and models that can be used to produce reasonable peak flow rates and hydrographs for use in flood-related studies and projects along drainage ways within the state. It is recommended that the flow rates, for the purpose of floodplain delineations, be calculated in accordance with the hydrology criteria presented in the statewide manual or by using other technically acceptable methods as approved by the CWCB and/or FEMA. OPERATING PRINCIPLE #7 - FLOODPLAIN DEVELOPMENT PRACTICES Communities through appropriate floodplain management practices should regulate areas that are subject to flooding from a IOO-year storm event. The CWCB recommends that communities adopt and enforce the floodplain managemenl criteria presented in the statewide manual. Communities are encouraged to