Last Updated 08/14/2026
Stormwater User Fee
The stormwater user fee shall be two dollars and twenty-five cents ($2.25) per equivalent residential unit (“ERU”) until and including June 30, 2015, and shall be one dollar and ten cents ($1.10) per base billing unit (“BBU”) beginning on July 1, 2015.
Prohibited Discharges
General discharge prohibitions.
It shall be unlawful to discharge or cause or allow discharge to any natural outlet or watercourse within the city any wastewater or other polluted waters or hazardous materials, except where suitable treatment has been provided in accordance with regulations adopted by CWA Authority and other applicable federal, state and local law.
Prohibited discharges to public sewers.
(a) No person shall discharge or cause to be discharged any stormwater, surface water, groundwater, roof runoff or subsurface drainage into any sanitary sewer.
(b) Stormwater and all other unpolluted drainage may be discharged through existing structures to such sewers as are specifically designated as combined sewers or storm sewers. No additional flow shall be introduced. Industrial cooling waters or unpolluted process waters may only be discharged upon approval by CWA Authority.
(c) No person shall discharge or cause to be discharged to any public sewer wastewater or pollutants other than in compliance with the regulations adopted by CWA Authority, and all other applicable federal, state and local law.
Operations and Maintenance Manual
The policies set forth in this section are intended to meet the requirements that the City address pollutants of concern in local stormwater runoff and comply with narrative standards in the permit. The water quality management program of the City of Indianapolis is performance-based. In a performance based program it is essential that any approved BMP be properly maintained to ensure that the BMPs perform as designed. An O&M Manual for any approved BMP will be required (see Section 102.06). As will be stated in the O&M Manual, maintenance will be the responsibility of the property/BMP owner. The City encourages the use of high-efficiency, low maintenance BMPs that have the potential for removal of multiple stormwater pollutants.
BMPs defined in Chapter 700 of this Manual as being capable of meeting the specified performance criteria for pollutant removal will be acceptable if designed to the standard specifications in Chapter 700 of this Manual.
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Frequently Asked Questions
Who calculates and collects Indianapolis and Marion County's stormwater user fee?
Marion County handles the billing side, even though the City of Indianapolis is the permitting authority for land disturbing activities. The fee shifted structure in 2015: it ran $2.25 per Equivalent Residential Unit through June 30 of that year, then moved to $1.10 per Base Billing Unit starting July 1, 2015. That switch from ERU to BBU terminology is worth knowing, since older documentation or third-party references to the fee may still use the earlier unit.
Are stormwater credits available for properties in Marion County?
Yes, for properties that maintain their own stormwater management facilities. The county’s water quality program is performance-based, meaning an approved best management practice only counts if it’s actually kept up to the standard set in its required Operations and Maintenance Manual. The city specifically encourages high-efficiency, low-maintenance BMPs capable of removing multiple pollutants at once, since those tend to hold their credit-qualifying performance longer with less upkeep.
Can stormwater be discharged into Indianapolis's sanitary sewer system?
No. Stormwater, surface water, groundwater, roof runoff and subsurface drainage are all prohibited from entering a sanitary sewer. Unpolluted drainage can go through existing structures into sewers specifically designated as combined or storm sewers, but no additional flow beyond what’s already accounted for can be introduced, and industrial cooling water or unpolluted process water needs separate approval from the CWA Authority before it can be discharged at all.
Who maintains an approved stormwater BMP once it's built in Marion County?
The information on this page is provided for general informational purposes only and is not legal advice. Regulations change frequently — AQUALIS makes no warranty as to the accuracy or completeness of this content, and any reliance on it is at your own risk. Consult a qualified professional or your local regulatory authority to confirm requirements applicable to your specific property.
