18 CFR § 415.42 - Technical standards.

(a) Standards used by state and local governments shall conform in principle to Commission standards but may vary in detail provided that resulting flood plain use will not be less restrictive than would result from the application of Commission standards. The Commission will review proposed state and local flood plain regulations to determine their compliance with Commission standards.

(b) Because of the variety and diversity of presently recognized hydrologic procedures, no one procedure or method is prescribed for determining the peak flow in cubic feet per second for the 100-year storm (Q 100) on which profiles for the delineation of flood hazard areas are based. The following may be used:

(1) A uniform Technique for Determining Flood Flow Frequencies—Bulletin No. 15—Water Resources Council, December 1967.

(2) Basin-Wide Program for Flood Plain Delineation—Delaware River Basin Commission—Anderson-Nichols & Co., Inc., June 1973.

(3) Magnitude and Frequency of Floods in New Jersey with Effects of Urbanization—Special Report 38 U.S.G.S.—New Jersey Department of Environmental Protection, 1974.

(4) Guidelines for Determining Flood Flow Frequency—Bulletin No. 17—Water Resources Council, March 1976.

State and local agencies may use methods resulting in Q 100s which are in reasonable agreement with those of the Commission. Any significant difference shall be reviewed with and subject to approval by the Executive Director.

(c) Methods and procedures shall be uniform, so far as practicable, within sub-basins which have a major effect on the larger basins of which they are a part. To assist in achieving this objective the Commission staff will periodically provide to the various interested governmental agencies and others Q 100 data as developed by the Delaware River Basin Commission Hydrology Coordinating Committee for key locations in the Delaware River Basin. These will be based on a Log Pearson Type 3 analysis of data from the U.S.G.S. gaging stations using station skew, regional skew, or weighted skew, depending on the scope of data at each station.