§ 24.20.080. Frequently flooded areas—General standards.

The following requirements apply, as applicable, to all uses and activities listed in Table 24.20-1.

A.

Applications to undertake a use or activity within frequently flooded areas or a 100-year channel migration hazard area shall contain all information necessary to evaluate the proposed activity, its impacts, its compliance with the applicable provisions of this chapter and Chapter 14.38 TCC, Development in Flood Hazard Areas.

B.

All development in frequently flooded areas and one-hundred-year channel migration hazard areas shall be designed to avoid habitat degradation, consistent with Chapter 24.25 TCC, Fish and Wildlife Habitat Conservation Areas.

C.

Development in frequently flooded areas shall be designed so it does not increase flood hazards, except as provided for in this section and Chapter 14.38 TCC.

D.

The approval authority shall deny proposed developments and uses if it is determined that they would require structural flood hazard reduction measures including, but not limited to, channeling the floodway or creating a new impact upstream or downstream at the time of construction/implementation or anytime thereafter, except as provided for in Chapter 24.25 TCC.

E.

Excavation and development shall be prohibited in the one-hundred-year floodplain of Type S and F streams if the approval authority determines that it would cause significant dewatering of the hyporheic zone (the saturated zone located beneath and adjacent to streams with subsurface flow between surface water and the water table), block ground water flow or significantly inhibit recharge of the hyporheic zone. The approval authority may require the applicant to submit data as necessary to determine if excavation, soil compaction, or impervious surfaces associated with the project would cause significant, detrimental disruption to the ground water system.

F.

The degree of flood protection required by this chapter is considered reasonable for regulatory purposes and is based on scientific and engineering considerations. Larger floods can and will occur on rare occasions. Flood heights may be increased by manmade or natural causes. This chapter does not imply that land outside of frequently flooded areas or usages permitted within such areas will not be subject to flooding or flood damage. This chapter shall not create liability on the part of Thurston County, any officer or employee thereof, or the Federal Insurance Administration, for any flood damages that result from reliance on this chapter or any administrative decision lawfully made hereunder.

(Ord. No. 14773, § 3(Att. B), 7-24-2012)