Admin Order 58-16-01 - Laserfiche WebLink

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Also, see measures for fish habitat protection below. (FEMA July 30, 1996 Memorandum in response to Region V.) Maintaining the capacity over time. After altering a watercourse; the developer has created an artificial situation and must assume responsibility for maintaining the capacity of the modified channel. If maintenance is not required, this can result in situations such as severe overgrowth or sediment deposition in channelized streams, causing reduced conveyance and increased flood hazards. In other cases, inadequate maintenance has resulted in erosion and scour problems within altered watercourses, thereby increasing potential floodwater velocities and downstream flood damages. Formal maintenance agreements, such as are required in other parts of the NFIP regulations, like for levees, are not specified or required for alterations of watercourses. Also, this requirement does not pertain to existing channels, whether natural or man -altered, that pre -dated the NFIP requirements (Call for Issues, June 2000, page II -3-29). FEMA's only requirement is for appropriate assurances that maintenance will be provided. These assurances should specify all maintenance activities, the frequency of their performance and the community officials responsible for their performance. Even in the case of bridges and culverts that may alter the watercourse, an arrangement must be made to maintain the flood carrying capacity of the channel. Such assurances can come in the form of a simple letter from a responsible community official. Maintenance should consist of a program of periodic inspections, routine channel clearing and other related functions (but see fish measures below). This is necessary for FEMA to verify that maintenance will be carried out in the event the community requests a map revision (Federal Register, May 6, 1988, page 16273, and November 3, 1987, page 42119). Oversize, and avoid the maintenance program. Some communities have design criteria for watercourse alterations that include factors that account for regrowth of vegetation, sediment deposition, etc., thus obviating the need for maintenance. This is a much better course of action as it relates to fish habitat enhancement in the Northwest, and is a practice recognized by FEMA in Section 65.6[a] [13] of the regulations: "...a community may submit, in lieu of the documentation specified in Section 65.6[a] [12] (the maintenance program), certification by a registered professional engineer that the project has been designed to retain its flood carrying capacity without periodic maintenance." What's best for fish? Recognizing the need to enhance fish habitat in the Northwest, there are several measures that communities can require relative to alteration of watercourses (including bank stabilization projects) that would not degrade fish habitat (some of the general standards in the preceding paragraphs, while FEMA policy for the Nation, would not be in the best interests of preserving fish habitat in this area): • Bridges should be used instead of culverts wherever possible; 2016 PIDS Manual, Appendix, B-3 B-3-3