A. “AKART” means “all known, available and reasonable methods of prevention, control and treatment.” “AKART” represents the most current methodology that can be reasonably required for preventing, controlling or abating the pollutants associated with a discharge. “AKART” applies to both point and nonpoint sources of pollution.

B. “Area of special flood hazard, Zone A” means the land in the floodplain within the City subject to a 1 percent or greater chance of flooding in any given year, but no base flood elevations were determined. Designated on maps as Zone A.

C. “Area of special flood hazard, Zone AE” means the land in the floodplain within the City subject to a 1 percent or greater chance of flooding in any given year, as determined by a detailed study, such as a flood insurance study or equivalent. Designation on maps always includes the letter “A” or “V.”

D. “Best management practices” or “BMPs” means schedules of activities, prohibitions of practices, general good housekeeping practices, pollution prevention and educational practices, maintenance procedures, and structural or managerial practices to prevent or reduce the discharge of pollutants directly or indirectly to stormwater, receiving waters, or stormwater conveyance systems. BMPs also include treatment practices, operating procedures, and practices to control site runoff, spillage or leaks, sludge or water disposal, or drainage from raw materials storage.

E. “Bioretention” means an engineered facility that stores and treats stormwater by passing it through a specified soil profile, and either retains or detains the treated stormwater for flow attenuation. Refer to the stormwater management manual for bioretention BMP types and design specifications.

F. “Construct or modify” means to install a new drainage pipe or ditch or make improvements to an existing drainage pipe or ditch (other than routine maintenance, repair or emergency modifications, excluding driveway culverts installed as part of single-family residential building permits) that either serves to concentrate previously unconcentrated surface and stormwater runoff, or serves to increase, decrease and/or redirect the conveyance of surface and stormwater runoff.

G. “Conveyance system” means the drainage facilities and features, both natural and constructed, which collect, contain and provide for the flow of surface and stormwater from the highest points on the land down to receiving water. The natural elements of the conveyance system include swales and small drainage courses, streams, rivers, lakes and wetlands. The constructed elements of the conveyance system include gutters, ditches, pipes, channels and most flow control and water quality treatment facilities.

H. “Department” means the City of Issaquah Public Works Engineering Department or its successor organization.

I. “Director” means the Director of Public Works Engineering Department, or any duly authorized representative of such Director.

J. “Discharge” means throw, drain, release, dump, spill, empty, emit, or pour any matter or to cause or allow matter to flow, run or seep from land or be thrown, drained, released, dumped, spilled, emptied, emitted, or poured into water.

K. “Ditch” means an artificially constructed watercourse designed to convey storm water, agricultural runoff or irrigation water. A stream or water of the state that has been artificially constructed or modified is not a ditch. Also see definition of “streams.”

L. “Drainage” means the collection, conveyance, containment and/or discharge of surface water or stormwater runoff.

M. “Drainage facility” means a constructed or engineered feature that collects, conveys, stores or treats surface and stormwater runoff. Drainage facilities shall include, but not be limited to, constructed or engineered streams, pipelines, channels, ditches, gutters, stormwater flow control or water quality treatment BMP/facilities, infiltration facilities, erosion and sediment control facilities and other structures and appurtenances that provide for drainage.

N. “Hazardous materials” means any material, either singularly or in combination, that is a physical or health hazard, whether the materials are in usable or waste condition; and any material that may degrade surface water or groundwater quality when improperly stored, handled, treated, used, produced, recycled, disposed of, or otherwise mismanaged. Hazardous materials shall also include: all materials defined as or designated by rule as a dangerous waste or extremely hazardous waste under Chapter 70.105 RCW and Chapter 173-303 WAC; hazardous materials shall also include petroleum or petroleum products that are in liquid phase at ambient temperatures, including any waste oils or sludges.

O. “Illicit connection” means a pipe or other stormwater facility that conveys anything not composed entirely of surface and stormwater directly to a stormwater facility or water body, except connections containing allowable discharges as defined in IMC 13.28.025.

P. “Illicit discharge” means any direct or indirect nonstormwater discharge to the City’s storm system, except as expressly allowed by this chapter.

Q. “Municipal separate storm sewer system (MS4)” means a conveyance or system of conveyances (such as roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, manmade channels, or storm drains):

R. “National Pollutant Discharge Elimination System (NPDES) stormwater discharge permit” means a permit issued by the Environmental Protection Agency (EPA) (or by the Washington Department of Ecology under authority delegated pursuant to 33 USC Section 1342(b)) that authorizes the discharge of pollutants to waters of the United States, whether the permit is applicable on an individual, group, or general area-wide basis.

S. “Nonstormwater discharge” means any discharge to the storm drain system that is not composed entirely of stormwater.

T. “Person” means any individual, association, organization, partnership, firm, corporation or other entity recognized by law and acting as either the owner of a premises, or as the owner’s agent.

U. “Pollutant” means anything which causes or contributes to pollution. Pollutants may include, but are not limited to: paints, varnishes, and solvents; oil and other automotive fluids; nonhazardous liquid and solid wastes and yard wastes; refuse, rubbish, garbage, litter, or other discarded or abandoned objects and accumulations, so that same may cause or contribute to pollution; floatables; pesticides, herbicides, and fertilizers; hazardous substances and wastes; sewage, fecal coliform and pathogens; dissolved and particulate metals; animal wastes; wastes and residues that result from constructing a building or structure; and noxious or offensive matter of any kind.

V. “Runoff” means water originating from rainfall and other precipitation that is found in drainage facilities, rivers, streams, springs, seeps, ponds, lakes and wetlands as well as shallow groundwater as well as on ground surfaces. For the purposes of this definition, “groundwater” means all waters that exist beneath the land surface or beneath the bed of any stream, lake or reservoir, or other body of surface water, whatever may be the geological formation or structure in which such water stands or flows, percolates, or otherwise moves.

W. “Site” means the legal boundaries of the 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.

X. “Source control BMP” means a structure or operation that is intended to prevent pollutants from coming into contact with stormwater through physical separation of areas or careful management of activities that are sources of pollutants. The Ecology Stormwater Management Manual for Western Washington separates source control BMPs into 2 types. Structural source control BMPs are physical, structural, or mechanical devices, or facilities that are intended to prevent pollutants from entering stormwater. Operational BMPs are nonstructural practices that prevent or reduce pollutants from entering stormwater.

Y. “Source control business inventory” means an inventory that identifies publicly and privately owned institutional, commercial, and industrial sites which have the potential to generate pollutants to the MS4 and shall include: (1) businesses and/or sites identified based on the presence of activities that are pollutant generating, and (2) other pollutant generating sources, based on complaint response, such as home-based businesses and multifamily sites.

Z. “Stormwater pollution prevention plan” means a document which describes the best management practices and activities to be implemented by a person to identify sources of pollution or contamination at a premises and the actions to eliminate or reduce pollutant discharges to stormwater, stormwater conveyance systems, and/or receiving waters to the maximum extent practicable.

AA. “Stream” means an area where water conveyed on the surface produces a defined channel or bed. A defined channel or bed is an area which demonstrates clear evidence of the passage of water and includes, but is not limited to, bedrock channels, gravel beds, sand and silt beds and defined-channel swales. The channel or bed need not contain water year-round. This definition is not meant to include entirely artificially constructed watercourses, including irrigation ditches, roadside ditches, canals, storm or surface water runoff conveyance devices or other artificial watercourses unless they have documented fish use and have a free and open surface connection to waters of the State or are used to convey water naturally occurring prior to construction. Also see definition of “Ditch”.

BB. “Surface water and stormwater” means water originating from rainfall and other precipitation that is found in drainage facilities, rivers, streams, springs, seeps, ponds, lakes and wetlands as well as shallow groundwater.

CC. “Stormwater design manual” means the Department of Ecology 2019 Stormwater Management Manual for Western Washington, prepared by the Department of Ecology, as supplemented and modified by the City of Issaquah 2022 Addendum to the Department of Ecology 2019 Stormwater Management Manual for Western Washington that specifies local requirements and procedures, describing surface and stormwater design and analysis requirements, procedures and guidance, as adopted by Chapter 16.26 IMC.

DD. “Stormwater facility” means a constructed component of a stormwater drainage system, designed or constructed to perform a particular function, or multiple functions. Stormwater facilities include, but are not limited to, pipes, swales, ditches, culverts, street gutters, detention ponds, retention ponds, constructed wetlands, infiltration devices, catch basins, oil water separators, and biofiltration swales. When used singularly or in combination, stormwater facilities reduce the potential for contamination of surface and/or groundwaters.

EE. “Stormwater treatment and flow control BMPs/facilities” means detention facilities, treatment BMPs/facilities, bioretention, vegetated roofs, and permeable pavements that help meet Minimum Requirements No. 6 (treatment), No. 7 (flow control), or both of the 2019-2024 Western Washington Phase II Municipal Stormwater Permit Appendix 1. (Ord. 2989 § 1 (Exh. A1), 2022; Ord. 2783 § 2 (Exh. A2), 2016; Ord. 2625 § 2, 2011; Ord. 2560 § 2 (Exh. A1), 2009; Ord. 2424 § 1, 2005; Ord. 2288 § 2, 2000).