Except as otherwise provided herein, or as new hydrologic and hydraulic techniques of nationwide scope and acceptance are developed and deemed acceptable by the commissioner, any federal, state, or local agency, any of their consultants, or any private consultants involved in the establishment and/or implementation of floodplain management studies or programs in Minnesota shall comply with technical standards prescribed in all applicable sections of these standards and criteria.
The regional flood shall serve as the basis for delineation of the floodplain and floodway for regulatory purposes.
The basic method of flood frequency analysis in the determination of regional flood flows shall be the log, Pearson Type III distribution (with log, normal as a special case) as described in the Federal Water Resources Council Bulletin 15, A Uniform Technique for Determining Flood Flow Frequencies, December 1967.
In those instances where inadequate stream flow data exists to allow use of the method outlined in the preceding paragraph, the commissioner may use or authorize use of other acceptable hydrologic methods or techniques.
Whenever the commissioner finds that sufficient technical information is available to estimate the magnitude of floods larger than the regional flood (such as the standard project flood) this information shall be made available by the commissioner to the local unit of government for use by the public as general information.
In order to provide uniformity in the analysis of flood hazards and the effects of various artificial and natural obstructions to flood flows within floodplain areas the commissioner will adopt and require use of a uniform system for the analysis of technical factors including:
minimum required survey data needed to provide adequate vertical and horizontal ground control elevations and distances for the channel of a stream or river and the adjoining floodplain area;
referencing of bench marks used for vertical control data; and
procedures for computation of water surface profiles and analysis of backwater effects in floodplain areas.
MS s 104.05
June 11, 2008