PART 238—WATER RESOURCES POLICIES AND AUTHORITIES: FLOOD DAMAGE REDUCTION MEASURES IN URBAN AREAS Authority: Pub. L. 738, 74th Congress, 33 U.S.C. 701a. Source: 45 FR 71801, Oct. 30, 1980, unless otherwise noted. § 238.1 Purpose. This regulation provides policies and guidance for Corps of Engineers participation in urban flood damage reduction projects and establishes criteria to distinguish between improvements to be accomplished by the Corps under its flood control authorities and storm sewer systems to be accomplished by local interests. § 238.2 Applicability. This regulation is applicable to all OCE elements and all field operating activities having Civil Works responsibilities. § 238.3 References. (a) Executive Order 11988—Floodplain Management, dated 24 May 1977. (b) U.S. Water Resources Council, Floodplain Management Guidelines, (43 FR 6030), to February 1978. (c) ER 1105-2-811. (d) ER 1140-2-302. (e) ER 1140-2-303. (f) EP 1165-2-2. § 238.4 Definitions. For purposes of this regulation the following definitions apply: (a) Urban areas (1) Provide general local government for specific population concentrations, and, (2) Occupy an essentially continuous area of developed land, containing such structures as residences, public and commercial buildings, and industrial sites. (b) Flood damage reduction works in urban areas (c) Storm sewer systems § 238.5 Comprehensive planning. Coordinated comprehensive planning at the regional or river basin level, or for an urban or metropolitan area, can help to achieve solutions to flood problems that adequately reflect future changes in watershed conditions, and help to avoid short-sighted plans serving only localized situations. This planning is particularly important in areas where significant portions of a watershed are expected to be urbanized in the future. Changes in land use may result in major alterations of the runoff characteristics of the watershed. Hydrologic changes must be projected for the period of analysis. In this effort, responsible local planning organizations should provide information and assist the Corps in development of projected land uses and expected practices for collection and conveyance of runoff over the period of analysis. Conversely, the Corps may be able to provide non-Federal interests with valuable information about water related consequences of alternative land uses and drainage practices. § 238.6 General policy. (a) Satisfactory resolution of water damage problems in urban areas often involves cooperation between local non-Federal interests and the Federal flood control agencies. In urban or urbanizing areas, provision of a basic drainage system to collect and convey the local runoff to a stream is a non-Federal responsibility. This regulation should not be interpreted to extend the flood damage reduction program into a system of pipes traditionally recognized as a storm drainage system. Flood damage reduction works generally address discharges that represent a serious threat to life and property. The decision criteria outlined below therefore exclude from consideration under flood control authorities small streams and ditches with carrying capacities typical of storm sewer pipes. Location of political boundaries will not be used as a basis for specifying project responsibility. Project responsibilities can be specified as follows: (1) Flood damage reduction works, as defined in this regulation, may be accomplished by the Corps of Engineers. (2) Construction of storm sewer systems and components thereof will be a non-Federal responsibility. Non-Federal interests have a responsibility to design storm sewer systems so that residual damages are reduced to an acceptable level. (b) Consideration will be given to the objectives and requirements of Executive Order 11988 (reference § 238.3(a)) and the general guidelines therefor by the U.S. Water Resources Council (reference § 238.3(b)). § 238.7 Decision criteria for participation. (a) Urban flood control. (2) A number of conditions within a drainage area may limit discharges for the 10-percent flood, without proportionately reducing discharges for larger floods, such as the one-percent flood. Examples include the presence of extremely pervious soils, natural storage (wetlands) or detention basins or diversions with limited capacity. Other conditions could result in a hydrological disparity between the 10- and one-percent flood events. (3) Division Engineers, except for NED and POD, are authorized to grant exceptions to the 800 cfs, 10-percent flood discharge criterion specified in this § 238.7(a)(1) whenever both of the following criteria are met: (i) The discharge for the one-percent flood exceeds 1800 cfs; and (ii) The reason that the 10-percent flood discharge is less than 800 cfs is attributable to a hydrologic disparity similar to those described in § 238.7(a)(2). Requests for exceptions to the hydrologic criterion contained in § 238.7(a)(1) from NED and POD should be submitted to HQDA (DAEN-CWP) WASH DC 20314. (4) Flood damage reduction works must conform to the definition in § 238.4(b) and must be justified based on Corps of Engineers evaluation procedures in use at the time the evaluation is made. Flood reduction measures, such as dams or diversions, may be located upstream of the particular point where the hydrologic criteria (and area criterion, if appropriate) are met, if economically justified by benefits derived within the stream reach which does qualify for flood control improvement. Similarly, the need to terminate flood control improvements in a safe and economical manner may justify the extension of some portions of the improvements, such as levee tiebacks, into areas upstream of the precise point where Federal flood control authorities become applicable. (b) Storm sewer system. (c) Man-made conveyance structures. (2) Man-made structures that convey sanitary sewage or storm runoff, or a combination of sanitary and storm sewage, to a treatment facility will not be classified as flood damage reduction works. Flows discharged into a natural or previously modified natural waterway for the purpose of conveying the water away from the urbanized area will be assumed to be a part of the flow thereof regardless of quality characteristics. (d) Joint projects. (e) Disagreements. § 238.8 Other participation. In addition to providing flood damage reduction works in urban areas, the Corps may provide related services to State and local governments on a reimbursable basis. Under Title III of the Inter-governmental Cooperation Act of 1968, specialized or technical services for which the Corps has specific expertise may be furnished only when such services cannot be procured reasonably and expeditiously from private firms (see ER 1140-2-303). § 238.9 Local cooperation. (a) Cost sharing and other provisions of local cooperation shall be in conformity with applicable regulations for structural and non-structural flood damage reduction measures. (b) Responsible non-Federal entities will be required to provide satisfactory assurances that they will adopt, enforce, and adhere to a sound, comprehensive plan for flood plain management for overflow areas of communities involved. To this end, District Engineers will inform HUD, and other concerned Federal and non-Federal planning and governing agencies, of flood plain management services available under Section 206 of the Flood Control Act of 1960, as amended (33 U.S.C. 709a). § 238.10 Coordination with other Federal agencies. In conducting flood damage reduction studies, reporting officers shall comply with the 1965 Agreement between the Soil Conservation Service and the Corps (contained in EP 1165-2-2) in determining the responsible Federal agency. Corps personnel should also keep abreast of the public works programs administered by other Federal agencies, such as the Environmental Protection Agency, the Department of Housing and Urban Development, Farmers Home Administration and the Department of Commerce, in order to coordinate flood control improvements with storm sewer system improvements and to avoid program overlap. Coordination of planning activities with A-95 clearinghouses will help to achieve this objective (see ER 1105-2-811).