17.30.1105 PERMIT REQUIREMENT

(1) Any person who discharges or proposes to discharge storm water from a point source must obtain coverage under an MPDES general permit or another MPDES permit for discharges:

(a) associated with construction activity;

(b) associated with industrial activity;

(d) from small municipal separate storm sewer systems that are identified in ARM 17.30.1102 or designated pursuant to ARM 17.30.1107;

(e) for which the department determines that storm water controls are needed based on wasteload allocations that are part of TMDLs that address the pollutants of concern; and

(f) that the department determines are contributing to a violation of a water quality standard or are significant contributors of pollutants to surface waters.

(2) For point source discharges of storm water identified in (1) (a) through (f) that are routinely composed entirely of storm water, authorization under an MPDES general permit must be obtained pursuant to this subchapter, unless the discharge is covered under an individual MPDES permit that is issued pursuant to ARM Title 17, chapter 30, subchapter 13 to the same owner or operator for other point source discharges.

(3) For point source discharges of storm water identified in (1) (a) through (f) that are not routinely composed of storm water, and that routinely discharge pollutants, coverage under an individual MPDES storm water permit or under an MPDES general permit must be obtained pursuant to ARM Title 17, chapter 30, subchapter 13.

(4) Any person who discharges or proposes to discharge storm water combined with municipal sewage from a point source shall obtain MPDES permits in accordance with the procedures set out in ARM Title 17, chapter 30, subchapter 13 and is not subject to the provisions of this subchapter.

(5) The department may waive the permit requirements in this subchapter for a storm water discharge associated with construction activity that disturbs less than five acres of total land area if either of the following two conditions exist:

(a) the value of the rainfall erosivity factor ("R" in the revised universal soil loss equation) is less than five during the period of construction activity. The period of construction activity extends through to final stabilization. The rainfall erosivity factor must be determined using a state-approved method. The owner or operator must certify to the department that the construction activity will take place only during a period when the value of the rainfall erosivity factor is less than five. If unforeseeable conditions occur that are outside of the control of the waiver applicant, and which will extend the construction activity beyond the dates initially applied for, the owner or operator shall reapply for the waiver or obtain authorization under the general permit for storm water discharges associated with construction activity. The waiver reapplication or notice of intent must be submitted within two business days after the unforeseeable condition becomes known; or

(b) storm water controls are not needed based on a TMDL approved or established by EPA that addresses the pollutants of concern or, for non-impaired waters that do not require TMDLs, an equivalent analysis that determines allocations for construction sites disturbing less than five acres of total land area for the pollutants of concern or that determines that such allocations are not needed to protect water quality based on consideration of existing in-stream concentrations, expected growth in pollutant contributions from all sources, and a margin of safety. For the purposes of this rule, pollutants of concern include sediment, or a parameter that addresses sediment (such as total suspended solids, turbidity or siltation) , and any other pollutant that has been identified as a cause of impairment of any water body that will receive a discharge from the construction activity. The operator shall certify to the department that the construction activity will take place, and that storm water discharges will occur, within the drainage area addressed by the TMDL or equivalent analysis.

(6) Prior to October 1, 1994, discharges composed entirely of storm water are not required to obtain an MPDES permit except for:

(a) discharges with respect to which an individual MPDES permit has been issued prior to February 4, 1987; and

(b) discharges listed in (1) (a) , (b) , (c) , and (f) , except that, for discharges listed in (1) (a) , this requirement applies only to storm water discharges associated with construction activity that will result in construction-related disturbance of five acres or more of total land area.

(7) For storm water discharges designated by the department under (1) (e) and (f) , the owner or operator shall apply for a permit within 180 days of receipt of the department's notice of designation, unless the department grants a later date.

(8) Except as provided in (9) , if not authorized under a storm water general permit, a permit application or notice of intent must be submitted to the department for stormwater discharges existing as of October 1, 1992, that are associated with:

(a) industrial activity;

(b) mining and oil and gas activity; and

(c) construction activity that will result in construction-related disturbances of five acres or more of total land area and for which storm water discharges are not authorized by a storm water general permit.

(9) For discharges identified in (8) (a) through (c) that are not authorized by a general or individual MPDES permit, and which are from a facility, other than an airport, powerplant, or uncontrolled sanitary landfill, that is owned or operated by a municipality with a population of under 100,000, the permit requirements in this subchapter are effective beginning March 10, 2003.

(10) The eligibility of an owner or operator of a discharge from an MS4 for funding under Title II, Title III, or Title VI of the federal Clean Water Act shall not be affected by the regulation or nonregulation of the MS4 under this subchapter.

(11) A person may petition the department to require an MPDES permit for a discharge that is composed entirely of storm water that contributes to a violation of a water quality standard or is a significant contributor of pollutants to surface waters.

History: 75-5-201, 75-5-401, MCA; IMP, 75-5-401, MCA; NEW, 2003 MAR p. 219, Eff. 2/14/03.