“Commercial or industrial unit” means any building or facility used other than as a dwelling unit.

“Development” shall mean any man-made change to improved or unimproved real property including but not limited to buildings or other structures, mining, dredging, filling, grading, paving, excavation or drilling operations.

“Equivalent residential unit (ERU)” means an area which is estimated to place approximately equal demand on the city’s storm drainage system as a single-family dwelling unit. One ERU shall be equal to 2,500 square feet of impervious surface.

“Impervious surfaces” are those surface areas which either prevent or retard saturation of water into the land surface, and/or cause water to run off the land surface in greater quantities or at an increased rate of flow from that present under natural conditions pre-existent to development. Common impervious surfaces include, but are not limited to, rooftops, concrete or asphalt sidewalks, walkways, patio areas, driveways, parking lots or storage areas and graveled, oiled, macadam or other surfaces which similarly impact the natural saturation or runoff patterns which existed prior to development.

“Improved premises” means any area which has been altered such that the runoff from the site is greater than that which could historically have been expected. Such a condition shall be determined by the city engineer.

“Mobile home” and “mobile home park” are defined as provided in ORS 446.003.

“Multiple-family unit (MFU)” means a building or facility under unified ownership and control and consisting of more than one dwelling unit with each such unit consisting of one or more rooms with bathroom and kitchen facilities designed for occupancy by one family and having a common water meter.

“Open drainageway” means a natural or man-made path, ditch or channel which has the specific function of transmitting natural stream water or storm runoff water from a point of higher elevation to a point of lower elevation.

“Runoff control” is any means approved by the city engineer by which the peak rate of storm runoff from development land surfaces is reduced.

“Single-family unit (SFU)” means that part of a building or structure which contains one or more rooms with a bathroom and kitchen facilities designed for occupancy by one family and where the units are sold and deeded as individual units and have individual water meters. A SFU is presumed to have 2,500 square feet of impervious surface area for purposes of this chapter. The term “SFU” shall be inclusive of those units identified as detached single-family residences, unit ownership, and condominiums, etc. (Ord. 1965 § 2, 2007)