40.386.010    Introduction

A.    Purpose. The purpose of this chapter is to safeguard public health, safety and welfare by protecting the quality of surface and groundwaters for drinking water supply, recreation, fishing and other beneficial uses through the application of best management practices (BMPs) for stormwater management and erosion control.

B.    Applicability.

1.    The provisions of this chapter shall apply to all new development, redevelopment, land-disturbing activities, and drainage projects, consistent with the Clark County Stormwater Manual.

2.    Meeting the requirements of this chapter is the joint and severable responsibility of both the owner(s) of the site on which land-disturbing activity occurs and the person(s) undertaking such activity, including the project applicant. In addition, if the land-disturbing activity involves a county-issued permit per other Clark County Code requirements, the applicant is also responsible for meeting the requirements of this chapter.

3.    The responsible official is authorized to enforce the provisions of this chapter using the remedies and procedures in Title 32.

C.    Exemptions from the Requirements of this Chapter. Exemption from the requirements of this chapter shall be granted for the following activities:

1.    Forest practices regulated under WAC Title 222, except Class IV general forest practices that are conversions from timber land to other uses.

2.    Construction of agricultural buildings or other hard surfaces for carrying out agricultural activities; provided, that no stormwater is released from the site directly or indirectly to the county’s stormwater conveyance system.

3.    Agricultural practices involving working the land for production, but not including converting forested land to agriculture.

4.    Landscape maintenance activities and gardening.

5.    Oil and gas field activities or operations including construction of drilling sites, waste management pits, and access roads, as well as construction of transportation and treatment infrastructure such as pipelines, natural gas treatment plants, natural gas pipeline compressor stations, and crude oil pumping stations. Operators are encouraged to implement BMPs to minimize erosion and to control sediment during and after construction activities to help ensure protection of surface water quality during storm events.

6.    The following pavement maintenance practices:

a.    Pothole and square cut patching;

b.    Overlaying existing asphalt or concrete pavement without expanding the area of coverage;

c.    Shoulder grading;

d.    Regrading/reshaping drainage systems;

e.    Crack sealing;

f.    Resurfacing with in-kind material without expanding the road prism;

g.    Pavement preservation, without expanding the road prism; and

h.    Vegetation management.

D.    Permit (Construction) Time Limit. All permits issued pursuant to the regulations contained in Chapter 40.385 or earlier stormwater code and the 2009 or earlier version of the Clark County Stormwater Manual expire on January 8, 2021, except if approved construction has begun on site before January 8, 2021. Beginning construction means, at a minimum, the site work associated with and directly related to the approved project has begun. For example: grading the project site to final grade, or the installation of utilities. Simply clearing the project site does not constitute the beginning of construction.

E.    Definitions. For the purposes of this chapter, the following definitions shall apply. Additional definitions can be found in the Department of Ecology Stormwater Management Manual for Western Washington.

Best management practices (BMPs)

“Best management practices (BMPs)” means schedules of activities, prohibitions of practices, maintenance procedures, managerial practices, and/or structural features approved by Ecology that, when used singly or in combination, prevent or reduce the release of pollutants and other adverse impacts to waters of Washington State.

Clark County Stormwater Manual

“Clark County Stormwater Manual” means the stormwater manual adopted by Ordinance 2015-11-24.

Drainage project

“Drainage project” means the excavation or construction of pipes, culverts, channels, embankments or other flow-altering structures in any stream, stormwater facility or wetland in Clark County.


“Ecology” means the Washington Department of Ecology.


“Engineer” means a professional who is licensed in the state of Washington as an engineer.

Hard surface

“Hard surface” means an impervious surface, a permeable pavement, or a vegetated roof.

Impervious surface

“Impervious surface” means a nonvegetated surface area which either prevents or retards the entry of water into the soil mantle as under natural conditions prior to development. A nonvegetated surface area which causes water to run off the surface in greater quantities or at an increased rate of flow from the flow present under natural conditions prior to development. Common impervious surfaces include, but are not limited to, roof tops, walkways, patios, driveways, parking lots or storage areas, concrete or asphalt paving, gravel roads, packed earthen materials, and oiled, macadam or other surfaces which similarly impede the natural infiltration of stormwater. Open, uncovered retention/detention facilities shall not be considered as impervious surfaces for the purposes of determining whether the thresholds for application of minimum requirements are exceeded. Open, uncovered retention/detention facilities shall be considered impervious surfaces for purposes of runoff modeling.

Land-disturbing activity

“Land-disturbing activity” means any activity that results in a change in the existing soil cover (both vegetative and nonvegetative) and/or the existing soil topography. Land-disturbing activities include, but are not limited to, clearing, grading, filling, and excavation. Compaction that is associated with stabilization of structures and road construction shall also be considered a land-disturbing activity. Vegetation maintenance practices, including landscape maintenance and gardening, are not considered land-disturbing activity. Stormwater facility maintenance is not considered land-disturbing activity if conducted according to established standards and procedures.

Low impact development

“Low impact development” means a stormwater and land use management strategy that strives to mimic predisturbance hydrologic processes of infiltration, filtration, storage, evaporation and transpiration by emphasizing conservation, use of on-site natural features, site planning, and distributed stormwater management practices that are integrated into a project design.


“Maintenance” means repair and upkeep activities conducted on currently serviceable structures, facilities, and equipment that involve no expansion or use beyond that previously existing and result in no significant adverse hydrologic impact. It includes those usual activities taken to prevent a decline, lapse, or cessation in the use of structures and systems. Those usual activities may include replacement of dysfunctional facilities, including cases where environmental permits require replacing an existing structure with a different type structure, as long as the functioning characteristics of the original structure are not changed.

Minimum requirements

“Minimum requirements” means the nine (9) sets of requirements that are part of the SMMWW, as follows:

• Minimum requirement No. 1: Preparation of stormwater site plans;

• Minimum requirement No. 2: Construction stormwater pollution prevention;

• Minimum requirement No. 3: Source control of pollution;

• Minimum requirement No. 4: Preservation of natural drainage systems and outfalls;

• Minimum requirement No. 5: On-site stormwater management;

• Minimum requirement No. 6: Runoff treatment;

• Minimum requirement No. 7: Flow control;

• Minimum requirement No. 8: Wetlands protection; and

• Minimum requirement No. 9: Operation and maintenance.

Native vegetation

“Native vegetation” means plant species, other than noxious weeds, that are indigenous to the coastal region of the Pacific Northwest and which reasonably could have been expected to naturally occur on the site.

New development

“New development” means:

• Land-disturbing activities;

• Class IV general forest practices that are conversions from timber land to other uses;

• Construction or installation of a building or other structure;

• Creation of impervious surfaces; and

• Subdivisions, short subdivisions, and binding site plans, as defined and applied in Chapter 58.17 RCW.

Projects meeting the definition of redevelopment shall not be considered new development.


“Redevelopment” means on a site that is already substantially developed (i.e., has thirty-five percent (35%) or more of existing hard surface coverage):

• The creation or addition of hard surfaces;

• The expansion of a building footprint or addition or replacement of a structure;

• Construction, installation or expansion of a building or other structure;

• Replacement of impervious surface that is not part of a routine maintenance activity; or

• Land-disturbing activities.

Regional stormwater facility

“Regional stormwater facility” means a stormwater facility that captures runoff from more than one (1) development or redevelopment project.

Responsible official

“Responsible official” means the Clark County Manager or his/her designee for the purposes of this chapter.


“Site” means the area within the legal boundaries of a parcel or parcels of land that is (are) subject to new development or redevelopment. For road projects, the length of the project site and the right-of-way boundaries define the site.

(Added: Ord. 2015-11-24)