Iowa Admin. Code r. 567-64.13

Current through Register Vol. 47, No. 8, October 30, 2024

Rule 567-64.13 - Storm water discharges

(1) The following is adopted by reference: 40 CFR Section 122.26.

(2) Small municipal separate storm sewer systems.

a. For any discharge from a regulated small municipal separate storm sewer system (MS4), the permit application must be submitted no later than March 10, 2003, if designated under this subrule.

b. All MS4s located in urbanized areas as defined by the latest decennial census and all MS4s which serve 10,000 people or more located outside urbanized areas and where the average population density is 1,000 people/square mile or more are regulated small MS4s unless waiver criteria established by the department are met and a waiver has been granted by the department.

c. Permit coverage requirements for MS4s located in urbanized areas and serving 1,000 or more people and fewer than 10,000 people may be waived if the following requirements are met:

(1) The department has evaluated all waters of the United States that receive a discharge from the MS4, and for all such waters, the department has determined that storm water controls are not needed based on wasteload allocations that are part of an EPA approved or established total maximum daily load (TMDL) that addresses the pollutants of concern or, if a TMDL has not been developed or approved, an equivalent analysis that determines sources and allocations for the pollutants of concern. The pollutants of concern include biochemical oxygen demand, sediment or a parameter that addresses sediment (total suspended solids, turbidity or siltation), pathogens, oil and grease, and any pollutant that has been identified as a cause of impairment of any water body that will receive a discharge from the MS4.

(2) The department has determined that future discharges from the MS4 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.

d. Permit coverage requirements for MS4s located in urbanized areas and serving fewer than 1,000 people may be waived if the following requirements are met:

(1) The system is not contributing substantially to the pollutant loadings of a physically interconnected MS4 that is regulated by the NPDES storm water program.

(2) The MS4 discharges any pollutants that have been identified as a cause of impairment of any water body to which the MS4 discharges and the department has determined that storm water controls are not needed based upon wasteload allocations that are a part of an EPA approved or established TMDL that addresses the pollutants of concern.

e. Permit coverage requirements for MS4s located outside of urbanized areas and serving 10,000 or more people may be waived if the following criterion is met:

The MS4 is not discharging pollutants which are the cause of the impairment to a water body designated by the department as impaired.

f. Should conditions under which the initial waiver was granted change, the waiver may be rescinded by the department and permit coverage may be required.

g. MS4 applications shall, at a minimum, demonstrate in what manner the applicant will develop, implement and enforce a storm water management program designed to reduce the discharge of pollutants from the MS4 to the maximum extent practicable, to protect water quality and to satisfy the appropriate water quality requirements of the Clean Water Act. The manner in which the permittee will address the following items must be addressed in the application: public education and outreach on storm water impacts, public involvement and participation, illicit discharge detection and elimination, construction site storm water runoff control, postconstruction storm water management in new development and redevelopment, and pollution prevention for municipal operations. Measurable goals which the applicant intends to meet and dates by which the goals will be accomplished shall be included with the application.

(3) Waivers for storm water discharge associated with small construction activity. The director may waive the otherwise applicable requirements in a general permit for storm water discharge from small construction activities as defined in 567-Chapter 60 when:

a. The value of the rainfall erosivity factor ("R" in the Revised Universal Soil Loss Equation) is less than 5 during the period of construction activity. The rainfall erosivity factor is determined in accordance with Chapter 2 of Agriculture Handbook Number 703, Predicting Soil Erosion by Water: A Guide to Conservation Planning With the Revised Universal Soil Loss Equation (RUSLE), pages 21-64, dated January 1997; or

b. Storm water controls are not needed based on a TMDL approved or established by the EPA that addresses the pollutant(s) of concern or, for nonimpaired waters that do not require TMDLs, an equivalent analysis that determines allocations for small construction sites for the pollutant(s) 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. The pollutant(s) of concern includes 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.

Iowa Admin. Code r. 567-64.13

ARC 7625B, IAB 3/11/09, effective 4/15/09

Amended by IAB February 9, 2022/Volume XLIV, Number 16, effective 3/16/2022