Duluth UDC (unnumbered, p.397: Definitions — I)

Illicit Discharge. Any direct or indirect non-stormwater discharge to the city separate storm sewer system. Illegal Connection. Shall mean any of the following: 1. Any pipe, open channel, drain or other conduit, whether natural or manmade, which is used exclusively to drain a non-stormwater discharge to the City's separate storm sewer system; or 2. Any pipe, open channel, drain or other conduit, whether natural or manmade, that was designed, installed or redirected for the purpose of draining a non-stormwater discharge into the City's separate storm sewer system; or 396 | P a g e Article Fourteen. Interpretation and Definitions 3. Any pipe, open channel, drain or other conduit, whether natural or manmade, which is connected to the city separate storm sewer system and which has not been documented in plans, maps, or equivalent records and approved by the city regardless of whether such pipe, open channel, drain or other conduit, whether natural or manmade, was permissible under law or practices applicable or prevailing at the time the connection was made, or has been previously allowed, permitted, or approved by the city or any other authorized enforcement agency. "Illegal connection" expressly includes, without limitation, those connections made in the past. Illuminated Sign. See “Sign, Illuminated.” Impervious Cover. A surface composed of any material that significantly impedes or prevents the natural infiltration of water into soil. Impervious surfaces include, but are not limited to, rooftops, buildings, streets and roads, and any concrete or asphalt surface. Impervious Surface. A man-made structure or surface that prevents the infiltration of storm water into the ground below the structure or surface. Examples are buildings, roads, driveways, parking lots, decks, swimming pools, or patios. Incidental Sign. See “Sign, Incidental.” Included bark. Bark that is caught between codominant stems, or a stem and a branch, and/or within narrow branch angles, creating a structural weakness. Industrial Activity, Regulated. Activities subject to NPDES industrial permits as defined in 40 CFR, section 122.26(b)(14). Industrial Stormwater Permit. A National Pollutant Discharge Elimination System (NPDES) permit issued to an industry or group of industries which regulates the pollutant levels associated with industrial stormwater discharges or specifies on-site pollution control strategies. International Society of Arboriculture, ISA. A worldwide professional organization dedicated to fostering a greater appreciation for trees and to promoting research, technology, and the professional practice of arboriculture. ISA administers certification programs for arborists, tree workers, utility arborists, and municipal arborists. Infiltration. The process of percolating stormwater runoff into the subsoil. Iridescent Color. A color that when seen at different angles has a play of lustrous rainbow-like colors; pearlescent. Inspection and Maintenance Agreement. A written agreement providing for the long-term inspection and maintenance of stormwater management facilities and practices on a site or with respect to a land development project, which when properly recorded in the deed records constitutes a restriction on the title to a site or other land involved in a land development project.