Section 327IAC15-13-3. MS4 area designation criteria

   (a) An MS4 entity that meets one (1) of the following is designated for permit coverage under this rule:

(1) Located within, or contiguous to, a mapped 2000 United States Census Bureau urbanized area (UA) and is:

(A) a municipality, regardless of its United States Census Bureau population; or

(B) a university, college, military base, hospital, or correctional facility with a full-time equivalent enrollment, daily user population, or bed count occupancy (based on the most recent enrollment count or population data) greater than or equal to one thousand (1,000).

(2) A county that contains a mapped UA. Only the portion of the county that contains the mapped UA, as delineated by political township or section, township, and range boundaries, must be regulated. If only a portion of the county contains a mapped UA, the MS4 entity may elect to regulate, to the extent of its authority, any additional portion of the county, as delineated by political township or section, township, and range boundaries, under this rule.

(3) A documented significant contributor of pollutants to waters or a regulated MS4 area.

(4) A municipality with a population density, according to 2000 United States Census Bureau data, of five hundred (500) people per square mile or greater and United States Census Bureau population of ten thousand (10,000) or more.

(5) A municipality with a population density, according to 2000 United States Census Bureau data, of five hundred (500) people per square mile or greater, United States Census Bureau population greater than seven thousand (7,000) and less than ten thousand (10,000), and having a positive, ten (10) year population growth percentage greater than or equal to ten percent (10%).

(6) A municipality with a population density, according to 2000 United States Census Bureau data, of five hundred (500) people per square mile or greater, United States Census Bureau population greater than seven thousand (7,000) and less than ten thousand (10,000), and having a university or college full-time equivalent enrollment, military base population, hospital bed count occupancy, or correctional facility daily user population (based on the most recent enrollment, count, or population data) that places the total population greater than or equal to ten thousand (10,000).

(7) A university, college, military base, hospital, or correctional facility with a full-time equivalent enrollment, daily user population, or bed count occupancy greater than or equal to one thousand (1,000), located within a designated municipality, and having responsibility for a storm water conveyance.

(8) A conservancy district or homeowner's association with a population within their service area of greater than or equal to one thousand (1,000) people, located within a designated municipality or mapped UA, and having responsibility for a storm water conveyance.

(9) A public or private storm water utility that serves one (1) or more of the MS4 entities designated under subdivisions (1) through (8).

  (b) An MS4 entity not already designated under subsection (a) may be designated for permit coverage if its discharge is to a sensitive area or if other environmental programs are not adequately protecting water quality.

  (c) Once an MS4 entity is designated under this section, it remains designated until the expiration of its permit unless any of the conditions for termination in section 20 of this rule are applicable or a waiver is granted in accordance with subsection (f).

  (d) The department shall notify MS4 entities meeting the designation criteria of this section in writing. If the department does not notify an MS4 entity in writing, an MS4 entity meeting the designation criteria of this section must comply with the requirements of section 9(e) of this rule.

  (e) A designated MS4 entity subject to this rule is also subject to the requirements of 327 IAC 15-2-9(b) and may be required to obtain an individual NPDES permit.

  (f) A designated MS4 entity may request a waiver from permit coverage under this rule. Unless an MS4 entity's conveyance system is substantially contributing to the pollutant loadings of a regulated, physically interconnected MS4 entity or a department determination is made that requires storm water controls, MS4 entities within a mapped UA that have a conveyance system serving a population of less than one thousand (1,000) are conditionally granted a waiver. For all other MS4 entities, this waiver will only be granted under the following conditions:

(1) The MS4 entity's conveyance system serves a population of less than ten thousand (10,000).

(2) The MS4 entity's conveyance system is not contributing substantially to the pollutant loadings of a physically interconnected MS4 entity that is regulated by this rule.

(3) An evaluation of all waters that receive a discharge from the MS4 entity's conveyance system has been conducted by the department or another approved entity.

(4) For all evaluated waters, the department has determined that storm water controls are not needed based on wasteload allocations that are part of a United States Environmental Protection Agency approved or established total maximum daily load or equivalent process and are reflective of pollutants identified as sources of impairment.

(5) The department has determined that future discharges from the MS4 entity's conveyance system do not have the potential to result in exceedances of water quality standards, including impairment of designated uses or other significant water quality impacts, including habitat and biological impacts.

(Water Pollution Control Division; 327 IAC 15-13-3; filed Jul 7, 2003, 2:15 p.m.: 26 IR 3577; errata filed Sep 8, 2003, 3:15 p.m.: 27 IR 191)