The county legislative authority of any county may adopt a comprehensive flood control management plan for any drainage basin that is located wholly or partially within the county.

A comprehensive flood control management plan shall include the following elements:

(1) Designation of areas that are susceptible to periodic flooding, from inundation by bodies of water or surface water runoff, or both, including the river's meander belt or floodway;

(2) Establishment of a comprehensive scheme of flood control protection and improvements for the areas that are subject to such periodic flooding, that includes: (a) Determining the need for, and desirable location of, flood control improvements to protect or preclude flood damage to structures, works, and improvements, based upon a cost/benefit ratio between the expense of providing and maintaining these improvements and the benefits arising from these improvements; (b) establishing the level of flood protection that each portion of the system of flood control improvements will be permitted; (c) identifying alternatives to in-stream flood control work; (d) identifying areas where flood waters could be directed during a flood to avoid damage to buildings and other structures; and (e) identifying sources of revenue that will be sufficient to finance the comprehensive scheme of flood control protection and improvements;

(3) Establishing land use regulations that preclude the location of structures, works, or improvements in critical portions of such areas subject to periodic flooding, including a river's meander belt or floodway, and permitting only flood-compatible land uses in such areas;

(4) Establishing restrictions on construction activities in areas subject to periodic floods that require the flood proofing of those structures that are permitted to be constructed or remodeled;

(5) Establishing restrictions on land clearing activities and development practices that exacerbate flood problems by increasing the flow or accumulation of flood waters, or the intensity of drainage, on low-lying areas. Land clearing activities do not include forest practices as defined in chapter 76.09 RCW; and

(6) Consideration of climate change impacts, including the impact of sea level rise and increased storm severity on people, property, natural resources, and the environment.

A comprehensive flood control management plan shall be subject to the minimum requirements for participation in the national flood insurance program, requirements exceeding the minimum national flood insurance program that have been adopted by the department of ecology for a specific floodplain pursuant to RCW 86.16.031, and rules adopted by the department of ecology pursuant to RCW 86.26.050 relating to floodplain management activities. When a county plans under chapter 36.70A RCW, it may incorporate the portion of its comprehensive flood control management plan relating to land use restrictions in its comprehensive plan and development regulations adopted pursuant to chapter 36.70A RCW.

Findings—Intent—1991 c 322: "(1) The legislature finds that:

(a) Floods pose threats to public health and safety including loss or endangerment to human life; damage to homes; damage to public roads, highways, bridges, and utilities; interruption of travel, communication, and commerce; damage to private and public property; degradation of water quality; damage to fisheries, fish hatcheries, and fish habitat; harm to livestock; destruction or degradation of environmentally sensitive areas; erosion of soil, stream banks, and beds; and harmful accumulation of soil and debris in the beds of streams or other bodies of water and on public and private lands;

(b) Alleviation of flood damage to property and to public health and safety is a matter of public concern;

(c) Many land uses alter the pattern of runoff by decreasing the ability of upstream lands to store waters, thus increasing the rate of runoff and attendant downstream impacts; and

(d) Prevention of flood damage requires a comprehensive approach, incorporating stormwater management and basin-wide flood damage protection planning.

(2) County legislative authorities are encouraged to use and coordinate all the regulatory, planning, and financing mechanisms available to those jurisdictions to address the problems of flooding in an equitable and comprehensive manner.

(3) It is the intent of the legislature to develop a coordinated and comprehensive state policy to address the problems of flooding and the minimization of flood damage." [ 1991 c 322 s 1.]

Purpose—1991 c 322: "The purpose of sections 3 through 13 of this act is to permit counties in cooperation and consultation with cities and towns to adopt a comprehensive system of flood control management and protection within drainage basins and to coordinate the flood control activities of the state, counties, cities, towns, and special districts within such drainage basins." [ 1991 c 322 s 2.]