15.14.300 Flood hazard reduction.
A. The following provisions apply to actions taken to reduce flood damage or hazard and to uses, development, and shoreline modifications that are proposed in flood hazard areas. Flood hazard reduction measures may consist of nonstructural measures, such as shoreline buffers, land use controls, wetland restoration, dike removal, use relocation, biotechnical measures, and storm water management programs, and of structural measures, such as dikes, levees, revetments, floodwalls, channel realignment, and elevation of structures consistent with the National Flood Insurance Program.
B. Although some flood hazard reduction measures may serve a dual function as shoreline stabilization, their primary purpose is to control the location of floodwaters directly. Alternatively, the primary purpose of shoreline stabilization measures is to prevent erosion of land from currents and waves originating in the shoreline waterbody (rather than upland sources of erosion), which is a more indirect control of the location of floodwater and non-floodwater. Shoreline stabilization is addressed in SPMC 15.14.440.
C. The town of South Prairie implements flood hazard reduction through the following means:
1. Plans and policies: Town of South Prairie comprehensive plan, Pierce County Rivers Flood Hazard Management Plan.
2. Regulations: Flood hazard area regulations.
D. Policies.
1. A comprehensive approach to flood hazard management should be taken by incorporating other flood regulations and plans.
2. Nonstructural Methods Preferred. Nonstructural flood hazard reduction methods are preferred over structural methods. Examples of nonstructural flood hazard methods are building setbacks, wetlands restoration, dike removal, and relocation of structures to less flood-prone areas.
3. New or Expanded Structures. New or expanded structures should be located to avoid the need of flood hazard reduction measures.
4. Bioengineered Flood Control Works. Flood control works should be bioengineered to enhance ecological functions, create a more natural appearance, and improve ecological processes unless proven to be infeasible.
E. Regulations.
1. Avoid Increase in Flood Hazards. Development in floodplains shall, consistent with applicable flood hazard plans and regulations (Chapter 15.16 SPMC (Flood Damage Prevention)), avoid significantly or cumulatively increasing flood hazards.
2. Uses and Activities Authorized in Floodway or CMZ. The following uses and activities may be authorized where appropriate and/or necessary within the channel migration zone or floodway:
a. Projects that protect or restore ecological functions or development with a primary purpose of restoring ecological functions;
b. Bridges, utility lines, public storm water facilities and outfalls, and other public utility and transportation structures where no other feasible alternative exists;
c. Repair and maintenance of an existing legally established use; provided, that channel migration is not further limited, or flood hazards to other uses increased;
d. Development that prevents active channel movement and flooding and where necessary for protection of legally existing structures or public safety;
e. Existing and ongoing agricultural practices; provided, that no new restrictions to channel movement occur;
f. Measures to reduce shoreline erosion; provided, that it is demonstrated that the erosion rate exceeds that which would normally occur in a natural condition and that the measure does not interfere with fluvial hydrological and geo-morphological processes normally acting in natural conditions.
3. Structural Flood Hazard Reduction Measures. New structural flood hazard reduction measures in shoreline jurisdiction shall be allowed only when it can be demonstrated by a scientific and engineering analysis that they are necessary to protect existing development and that nonstructural measures are not feasible.
4. Placement of Structural Flood Hazard Reduction Measures. New structural flood hazard reduction measures shall be placed landward of associated wetlands and designated shoreline buffers, except for actions that increase ecological functions, such as wetland restoration.
5. Public Access. See SPMC 15.14.310(B).
6. Gravel Removal. The removal of gravel for flood management purposes shall be consistent with SPMC 15.14.380 (Dredging), and be allowed only after a biological and geo-morphological study shows that extraction has a long-term benefit to flood hazard reduction, does not result in a net loss of ecological functions, and is part of a comprehensive flood management solution.
7. New Development and Subdivisions. Approve new development or subdivisions when it can be reasonably foreseeable that the development or use would not require structural flood hazard reduction measures within the channel migration zone or floodway during the life of the development.
8. Roads and Railroads. Roads or railroads shall be built outside of shoreline jurisdiction except for necessary crossings, and repair or maintenance of existing roads and railroads. New transportation facilities shall be designed so that no significant loss of floodway capacity or measurable increase in predictable flood levels will result based on studies submitted by applicants and approved by the town. [Ord. 580 Att. A § 4.3, 2019.]