Establishment of the County Floodplain and Danger Reach: The Department shall establish as the County floodplain areas of the County that are subject to inundation by the 1-percent annual chance (100-year) flood and shall delineate these areas on the official floodplain maps that shall be prepared and maintained in force as part of this Division. Where flood elevations have been defined, the County floodplain shall be determined based on 1-percent annual chance (100-year) flood elevations rather than the area graphically delineated on the official floodplain maps. Area included. The County floodplain shall include all of the following areas: 1-percent annual chance (100-year) floodplain as determined by FEMA, including all of the following FEMA subcategories (also found in the Definitions section): Zone A; Zone AE and Zone A1-30; Zone AH and Zone AO; and Zone VE and Zone V1-30. Special flood hazard areas, as defined herein and identified by the County. Wetland floodplains - areas of wetland subject to inundation by the 1-percent annual (100-year) flood. Area delineated by approved County Comprehensive Watershed Management Plans and supporting data to be subject to the 1-percent annual (100-year) flood or determined to be subject to the 100-year flood by any other floodplain study approved by the County. Areas delineated by any other floodplain studies prepared using the County's GIS-based floodplain models. Danger reach of a dam - The applicant shall define the area that will be flooded when a dam has been breached by flood waters, as established by using the latest methodology of the Maryland Department of the Environment. The danger reach limits are to be shown on the 1-percent annual chance (100-year) floodplain delineation mapping and labelled as danger reach limits. Danger reach limits that extend beyond the 1-percent chance (100-year) floodplain limits are not considered to be included in the 1-percent chance (100-year) floodplain area. Floodplain buffer area - where proposed development is associated with a stream or tributary and the limits of the floodplain cannot be accurately determined because of the lack of detailed floodplain data and analysis or because of unknown effects of future development in the watershed, the Department may require that an approximated floodplain boundary and a floodplain buffer be established and maintained as part of the development. The floodplain buffer is twenty-five (25) feet, measured outside the approximated 1-percent annual chance (100-year) floodplain delineation. The floodplain buffer is considered part of the 1-percent annual chance (100-year) floodplain delineation and it is included in the floodplain easement. Areas excluded - areas associated with a watercourse having a drainage area less than fifty (50) acres of watershed may be excluded, from the County 1-percent annual chance (100-year) floodplain, subject to the approval of the Department. Sources - the County shall use the following sources for identifying the floodplain: The effective FEMA Flood Insurance Study for Prince George's County, Maryland; The most current FEMA Flood Insurance Rate Maps; Approved County comprehensive watershed management plans; Other floodplain studies approved by the County; and Other floodplain studies prepared by the County or its designee using the County's GIS-based floodplain models. Where conflicting elevations are found among the above sources, the highest elevation shall govern, including the appropriate freeboard. Revisions of the County floodplain: The Department may amend the limits of the County floodplain to reflect the effect of specified flood protection measures recommended in adopted County watershed plans that have been included in an adopted Prince George's County Capital Improvement Program (CIP) for planning, design and construction, and for which the County has all necessary federal and state permits, construction has been completed, and an as-built certification has been issued. However, the County floodplain may not be based upon flood elevations lower than shown on the effective FEMA map until concurrence in the lowered elevations has been received from FEMA in accordance with applicable federal regulations. The County floodplain limits shall be amended by the Department where studies or information provided by a qualified agency or person document the need or possibility for such revision. Where there are no available studies, or where existing studies have been determined by the Department to be inadequate, a new study of the area shall be required. All such floodplain studies shall be performed in accordance with the Department's requirements and criteria, which shall include, without limitation: System within the drainage basin either existing or included in an adopted County CIP for planning, design and construction and, for which the County has all necessary federal and state permits, and construction has been completed; and Future land use based on existing zoning or based on adopted or approved master plans, or sectional map amendments, whichever best reflects future land use in the opinion of the County. Revisions to the floodplain that reflect changes, including but not limited to constructed grading, road crossings, culverts, dams, embankments, bridges, changes in channel lining or vegetative cover. FEMA Floodplain Modification: Any proposed reduction or modification to any area of the County identified by FEMA as part of the 1-percent annual chance (100-year) floodplain must have the approval of FEMA, as outlined in the NFIP regulations. Proposed modifications, including modifications based on existing conditions, proposed construction, or as built conditions, must first be submitted to the Department and the Prince George's County Department of the Environment for review, and the Department's recommendation on the proposed modification shall be transmitted to FEMA with a copy to the submitter. Any proposed development in the FEMA floodplain, which may result in any increase or decrease in base flood elevations or change to the FEMA floodplain boundaries, must be modeled and submitted to the Department and the Prince George's County Department of the Environment for review. If the proposed encroachment causes the base flood elevation to increase by more than one (1) foot at any point within the community, the permit must be submitted to and approved by FEMA for a Conditional Letter of Map Revision (CLOMR) prior to the issuance of a permit. A CLOMR is required for any encroachment in the FEMA Floodway that would result in an increase in the base flood elevation. An applicant must submit a Letter of Map Revision (LOMR) to FEMA once a project has been completed. A LOMR is required for any project that results in any change in the floodplain elevation of a half a foot or greater, and any project that results in any change in the floodplain limit that is scaleable on the FEMA maps. Hydrologic and hydraulic analysis based on the effective FEMA floodplain models must be performed in accordance with standard engineering practices and certified by a registered professional engineer and must be submitted to FEMA for approval. Failure to receive an approval letter from FEMA shall be grounds for denial of the permit. The Department shall notify the Federal Insurance Administrator of revisions to the FEMA floodplain within six (6) months after the date of completion of the modification by submitting technical and scientific data in accordance with 44 Code of Federal Regulations, Part 65. All revisions and modifications of the FEMA floodplain shall be subject to the review and approval by FEMA, the Department and the Prince George's County Department of the Environment. The Department shall provide the County floodplain maps to the public, upon request.