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 Thurston County
 Code of Ordinances
 Title 24. CRITICAL AREAS
 Chapter 24.20. FREQUENTLY FLOODED AREAS

  § 24.20.070. Frequently flooded areas—Standards and allowable uses and activities.  

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  • Table 24.20-1 identifies the land uses and activities that are allowable in frequently flooded areas (i.e., one-hundred-year floodplains, one-hundred-year flood zone (one percent flood zone), floodways, high ground water hazard areas/restricted development zones, channel migration hazard areas, and coastal flood hazard areas) and one-hundred-year channel migration hazard areas. All land uses and activities not allowed by or not mentioned in Table 24.20-1, except water dependent uses allowed under the Shoreline Master Program for Thurston Region, are prohibited within the flood and channel migration hazard areas regulated by this section, except as otherwise provided in Chapter 24.01 TCC. In addition to this chapter, these allowable uses and activities may be subject to the following:

    A.

    Other applicable provisions of this title and requirements of the applicable zoning district;

    B.

    The provisions of Chapter 14.38 TCC, Development in Flood Hazard Areas;

    C.

    The Shoreline Master Program for the Thurston Region;

    D.

    The Drainage Design and Erosion Control Manual for Thurston County, as amended (Chapter 15.05 TCC); and

    E.

    All other applicable county, state, and federal regulations.

    Table 24.20-1. Allowable Uses and Activities in Flood and Channel Migration Hazard Areas

    Uses and Activities Floodways Frequently Flooded
    Areas (except floodways and high groundwater hazard areas)     		Channel Migration Hazard Areas High Ground Water Hazard Areas/RDZ Coastal Flood Hazard Areas
    Accessory structures - Construction
    TCC 24.20.080     		X P P P P
    Antenna support structures regulated by Chapter 20.33 TCC
    TCC 24.20.080     		X P P P X
    Asphalt plants X X X X X
    Boat ramp and associated vehicle access
    TCC 24.20.080     		P P P P P
    Boat site, hand launch - Construction
    TCC 24.20.080     		P P P N/A P
    Bridges and culverts - Maintenance or repair
    TCC 24.20.080; 24.20.140     		P P P A A
    Bridges and culverts - Replacement or expansion
    TCC 24.20.145     		P P P A P
    Bridges and culverts - New construction
    TCC 24.20.140     		P P P P P
    Cemeteries
    TCC 24.20.080     		X X X X X
    Clearing and grading/timber harvest in conjunction with a development project
    TCC 24.20.090     		P P P P P
    Critical facilities
    TCC 24.20.080     		X X X X X
    Drainage ditch maintenance
    TCC 24.20.080     		A A A A A
    Drilling and testing for required report or engineering study
    TCC 24.20.080     		A A A A A
    Emergency response SEE CHAPTER 24.90 TCC
    Existing lots approved prior to the effective of the ordinance from which this title derives - Construction of primary structures and associated, decks, garages, and appurtenant structures X P P P P
    Fences X A A A A
    Fill - Associated with a permitted use
    TCC 24.20.100
    TCC 14.38     		X P P P X
    Fish hatchery construction and maintenance
    TCC 24.20.080     		P P P P P
    Floats (e.g., a floating dock, mooring buoy, navigational aid, and swimming float) - Installation
    TCC 24.20.080     		P X X N/A A
    Flood protection facilities - New construction
    TCC 24.20.080     		P P P P X
    Flow control facilities/dams - New construction
    TCC 24.20.080     		P P P P X
    Forestry - Conversion Class IV forest practice
    TCC 24.20.080     		P P P P P
    Gardens for personal consumption - New and expanded
    TCC 24.20.080     		A A A A A
    Golf courses
    TCC 24.20.080     		X P P P P
    Habitat restoration/enhancement
    TCC 24.20.080     		P P P P P
    Hazardous substances
    TCC 24.20.120     		X X P X X
    Hazardous substances - Residential Scale
    TCC 24.20.120     		P P P P P
    Infiltration of reclaimed water (application to the land's surface above agronomic rates)*
    TCC 24.20.132
     
    *Critical area regulations will be proposed when more information is available to Thurston County from the Regional Groundwater Recharge Scientific Study, and using other studies and information for reclaimed water following the requirements of the Growth Management Act (Chapter 36.70A RCW).     		X X X X X
    Instream structures - Maintenance or repair
    TCC 24.20.080     		A A N/A A A
    Instream structures not addressed above - New construction
    TCC 24.20.080     		P N/A N/A P N/A
    Lawfully established existing uses A A A A A
    Lawns, landscaping, golf courses, and cemeteries - Maintenance
    TCC 24.20.080     		A A A A A
    Marine railway
    TCC 24.20.080     		X P P N/A P
    Mineral extraction
    TCC 24.20.080     		X X X P X
    Mitigation required by the County
    TCC 24.20.080     		P P P P P
    Nonconforming structure/use - Maintenance, repair, alteration, expansion, intensification, or replacement SEE CHAPTER 24.50 TCC
    On-site sewage disposal system - New
    TCC 24.20.130     		X X P X X
    On-site sewage disposal system, drainfield, or well/pump - Maintenance or repair
    TCC 24.20.130     		P P A A A
    Open space (e.g., critical area tract) A A A A A
    Piers - Construction
    TCC 24.20.080     		P P X N/A A
    Ponds - New creation <1 acre
    TCC 24.20.080     		X P P P X
    Public facility
    TCC 24.20.080     		X X X X X
    Public park facilities, trails and developed recreation areas - Maintenance
    TCC 24.20.080     		A A A A A
    Public project of significant importance
    TCC 24.20.080     		X X X X X
    Recreation (outdoors) - Passive and low impact activities (e.g., bird watching, boating, bicycling, canoeing, fishing, hiking, horseback riding, hunting, jogging, photography, swimming, and similar activities) A A A A A
    (Active) Recreation facilities (e.g., swimming access, public and private parks, day camps and camping sites not including structures)
    TCC 24.20.080     		X P P P P
    Research (e.g., education, scientific, and site investigation)
    TCC 24.20.080     		A A A A A
    Residential - Single-family home, new
    TCC 24.20.135     		X X P P X
    Roads/railroads - Repair and maintenance
    TCC 24.20.080     		A A A A A
    Roads/railroads - Replacement of lawfully established roads/railroads within maintained, improved (paved or railroad tracks) road rights-of-way or easements, or railroad prism
    TCC 24.20.145     		P P P A A
    Roads - Expansion
    TCC 24.20.080     		P P P P P
    Roads - New construction, including private access
    TCC 24.20.140     		P P P P P
    Scientific sampling
    TCC 24.20.080     		A A A A A
    Shoreline protective structures/armoring (e.g., bulkhead, gabion, riprap, or wall)
    TCC 24.20.080     		P P P P P
    Signs (e.g., interpretation, critical area tract, and survey markers,) A A A A A
    Ski lake - Creation
    TCC 24.20.080     		X P P A A
    Slope stabilization or retaining wall (not a bulkhead)
    TCC 24.20.080     		P P P P P
    Stabilization techniques (nonstructural)/bioengineering
    TCC 24.20.080     		P P P P P
    Stair lower, stairway or mechanical lift
    TCC 24.20.080     		X P X P P
    Stormwater conveyance system or detention/treatment facility - Maintenance or repair
    TCC 24.20.150     		P A A A A
    Stormwater retention/treatment facility - Construction
    TCC 24.20.150     		X P P P X
    Stormwater - Sediment control ponds (temporary) - Construction
    TCC 24.20.150     		X P P P P
    Stormwater - Surface water conveyance system - Construction
    TCC 24.20.150     		P P P P P
    Stream flow and elevation gages - Installation A A A A A
    Stream relocation (see Chapter 24.25 TCC) P P P P P
    Subdivisions (see Chapter 24.55 TCC) P P P P P
    Trails/paths, elevated walkways, and associated facilities - New construction (interpretative site and viewing platform)
    TCC 24.20.080     		P P P P P
    Utility facilities and lines - Maintenance or repair
    TCC 24.20.080     		A A A A A
    Utilities - Replacement
    TCC 24.20.080     		P P P P P
    Utility transmission lines - New construction outside of existing improved roads and utility corridors and new utility corridors
    TCC 24.20.165     		P P P P P
    Utility lines in improved roads and utility corridors and easements - New installation or replacement
    TCC 24.20.165     		P A P A A
    Utility service lines - Installation
    TCC 24.20.165     		P A A A A
    Utility facility - New facilities such as lift stations, substations and utility poles
    TCC 24.20.165     		X P X P P
    Vegetation removal - Enhancement projects
    TCC24.20.170     		P A P A A
    Vegetation removal - Noxious weeds
    TCC 24.20.170     		A A A A A
    Vegetation removal - Invasive vegetation
    TCC 24.20.170     		P P A A A
    Vegetation removal - Hazard trees
    TCC 24.20.170     		P P P P P
    Vegetation removal - Aquatic weeds
    TCC 24.20.170     		P N/A N/A N/A N/A
    Wells - New construction
    TCC 24.20.180     		X P P P X
    Wildlife blind or nesting structure A A A A A
    Uses allowed in the applicable zoning district/shoreline master program not listed elsewhere in this table X X X P A

     

    LEGEND:

    A = Allowed, subject to applicable standards

    P = Allowed, subject to applicable standards and Critical Areas Review Permit

    X = Prohibited

(Ord. No. 14773, § 3(Att. B), 7-24-2012; Ord. No. 14961, §§ 2(Att. B), 5(Att. E), 12-17-2013)